WIP: generate examples from Tapeti message classes from NuGet feeds

- Implementation of assembly/nuget package selection UI
- Actual example generation needs more work

PettingZoo.Core/Generator/IExampleGenerator.cs

@@ -1,25 +1,33 @@
 using System;
-using System.Collections.Generic;
 
 namespace PettingZoo.Core.Generator
 {
-    public interface IExampleSource : IDisposable
+    public interface IExampleGenerator
     {
-        IExampleFolder GetRootFolder();
+        void Select(object? ownerWindow, Action<IExample> onExampleSelected);
     }
 
 
-    public interface IExampleFolder
+    public interface IExample
-    {
-        public string Name { get; }
-
-        public IReadOnlyList<IExampleFolder> Folders { get; }
-        public IReadOnlyList<IExampleMessage> Messages { get; }
-    }
-
-
-    public interface IExampleMessage
     {
         string Generate();
     }
+
+
+    public interface IClassTypeExample : IExample
+    {
+        public string AssemblyName { get; }
+        public string? Namespace { get; }
+        public string ClassName { get; }
+
+        public string FullClassName => !string.IsNullOrEmpty(Namespace) ? Namespace + "." : "" + ClassName;
+    }
+
+
+    /*
+    public interface IValidatingExample : IExample
+    {
+        bool Validate(string payload, out string validationMessage);
+    }
+    */
 }

PettingZoo.Core/Rendering/MessageBodyRenderer.cs

@@ -7,7 +7,7 @@ namespace PettingZoo.Core.Rendering
 {
     public class MessageBodyRenderer
     {
-        public static Dictionary<string, Func<byte[], string>> ContentTypeHandlers = new()
+        private static readonly Dictionary<string, Func<byte[], string>> ContentTypeHandlers = new()
         {
             { "application/json", RenderJson }
         };
@@ -15,7 +15,7 @@ namespace PettingZoo.Core.Rendering
 
         public static string Render(byte[] body, string? contentType)
         {
-            return (contentType != null) && ContentTypeHandlers.TryGetValue(contentType, out var handler)
+            return contentType != null && ContentTypeHandlers.TryGetValue(contentType, out var handler)
                 ? handler(body) 
                 : Encoding.UTF8.GetString(body);
 

PettingZoo.Core/Settings/PettingZooPaths.cs

@@ -0,0 +1,26 @@
+using System;
+using System.IO;
+using System.Reflection;
+
+namespace PettingZoo.Core.Settings
+{
+    public static class PettingZooPaths
+    {
+        public static string AppDataRoot { get; }
+        public static string InstallationRoot { get; }
+
+
+        static PettingZooPaths()
+        {
+            var appDataPath = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);
+            if (appDataPath == null)
+                throw new IOException("Could not resolve application data path");
+
+            AppDataRoot = Path.Combine(appDataPath, @"PettingZoo");
+            if (!Directory.CreateDirectory(AppDataRoot).Exists)
+                throw new IOException($"Failed to create directory: {AppDataRoot}");
+
+            InstallationRoot = Path.GetDirectoryName(Assembly.GetEntryAssembly()?.Location ?? Assembly.GetExecutingAssembly().Location)!;
+        }
+    }
+}

PettingZoo.Settings.LiteDB/BaseLiteDBRepository.cs

@@ -1,5 +1,6 @@
 using LiteDB;
 using LiteDB.Async;
+using PettingZoo.Core.Settings;
 
 namespace PettingZoo.Settings.LiteDB
 {
@@ -15,15 +16,7 @@ namespace PettingZoo.Settings.LiteDB
 
         public BaseLiteDBRepository(string databaseName)
         {
-            var appDataPath = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);
+            databaseFilename = Path.Combine(PettingZooPaths.AppDataRoot, $"{databaseName}.litedb");
-            if (appDataPath == null)
-                throw new IOException("Could not resolve application data path");
-
-            var databasePath = Path.Combine(appDataPath, @"PettingZoo");
-            if (!Directory.CreateDirectory(databasePath).Exists)
-                throw new IOException($"Failed to create directory: {databasePath}");
-
-            databaseFilename = Path.Combine(databasePath, $"{databaseName}.litedb");
         }
 
 

PettingZoo.Tapeti/AssemblyLoader/FilePackageAssemblies.cs

@@ -0,0 +1,45 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace PettingZoo.Tapeti.AssemblyLoader
+{
+    public class FilePackageAssemblies : IPackageAssemblies
+    {
+        private readonly string[] filenames;
+
+
+        public FilePackageAssemblies(params string[] filenames)
+        {
+            this.filenames = filenames;
+        }
+
+
+        public Task<IEnumerable<IPackageAssembly>> GetAssemblies(IProgress<int> progress, CancellationToken cancellationToken)
+        {
+            return Task.FromResult(filenames.Select(f => (IPackageAssembly)new FilePackageAssembly(f)));
+        }
+
+
+
+        private class FilePackageAssembly : IPackageAssembly
+        {
+            private readonly string filename;
+
+
+            public FilePackageAssembly(string filename)
+            {
+                this.filename = filename;
+            }
+
+
+            public Stream GetStream()
+            {
+                return new FileStream(filename, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
+            }
+        }
+    }
+}

PettingZoo.Tapeti/AssemblyLoader/IPackageAssemblies.cs

@@ -0,0 +1,19 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace PettingZoo.Tapeti.AssemblyLoader
+{
+    public interface IPackageAssemblies
+    {
+        Task<IEnumerable<IPackageAssembly>> GetAssemblies(IProgress<int> progress, CancellationToken cancellationToken);
+    }
+
+
+    public interface IPackageAssembly
+    {
+        Stream GetStream();
+    }
+}

PettingZoo.Tapeti/AssemblyLoader/NuGetPackageAssemblies.cs

@@ -0,0 +1,82 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using System.Runtime.Versioning;
+using System.Threading;
+using System.Threading.Tasks;
+using NuGet.Frameworks;
+using NuGet.Packaging;
+using PettingZoo.Tapeti.NuGet;
+
+namespace PettingZoo.Tapeti.AssemblyLoader
+{
+    public class NuGetPackageAssemblies : IPackageAssemblies
+    {
+        private readonly INuGetPackageVersion packageVersion;
+
+
+        public NuGetPackageAssemblies(INuGetPackageVersion packageVersion)
+        {
+            this.packageVersion = packageVersion;
+        }
+
+
+        public async Task<IEnumerable<IPackageAssembly>> GetAssemblies(IProgress<int> progress, CancellationToken cancellationToken)
+        {
+            await using var packageStream = new MemoryStream();
+            await packageVersion.Download(packageStream, cancellationToken);
+
+            packageStream.Seek(0, SeekOrigin.Begin);
+            using var packageReader = new PackageArchiveReader(packageStream);
+
+            // Determine which frameworks versions PettingZoo is compatible with so that we can actually load the assemblies
+            var targetFrameworkAttribute = Assembly.GetExecutingAssembly()
+                .GetCustomAttributes(typeof(TargetFrameworkAttribute), false)
+                .Cast<TargetFrameworkAttribute>()
+                .Single();
+
+            var targetFramework = NuGetFramework.ParseFrameworkName(targetFrameworkAttribute.FrameworkName, DefaultFrameworkNameProvider.Instance);
+
+            var libVersion = (await packageReader.GetLibItemsAsync(cancellationToken))
+                .Where(l => DefaultCompatibilityProvider.Instance.IsCompatible(targetFramework, l.TargetFramework))
+                .OrderByDescending(l => l.TargetFramework)
+                .FirstOrDefault();
+
+            if (libVersion == null)
+                return Enumerable.Empty<IPackageAssembly>();
+
+
+            var assemblies = new List<IPackageAssembly>();
+
+            foreach (var filename in libVersion.Items.Where(f => f.EndsWith(@".dll", StringComparison.InvariantCultureIgnoreCase)))
+            {
+                var assembly = await new NuGetPackageAssembly().CopyFrom(packageReader.GetStream(filename));
+                assemblies.Add(assembly);
+            }
+
+            return assemblies;
+        }
+
+
+
+        private class NuGetPackageAssembly : IPackageAssembly
+        {
+            private readonly MemoryStream buffer = new();
+
+
+            public async Task<IPackageAssembly> CopyFrom(Stream stream)
+            {
+                await stream.CopyToAsync(buffer);
+                return this;
+            }
+
+
+            public Stream GetStream()
+            {
+                return new MemoryStream(buffer.GetBuffer());
+            }
+        }
+    }
+}

PettingZoo.Tapeti/AssemblyParser/AssemblyParser.cs

@@ -0,0 +1,83 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using System.Runtime.InteropServices;
+using Newtonsoft.Json;
+using PettingZoo.Core.Generator;
+using Tapeti.DataAnnotations.Extensions;
+
+namespace PettingZoo.Tapeti.AssemblyParser
+{
+    public class AssemblyParser : IDisposable
+    {
+        private readonly MetadataLoadContext loadContext;
+
+        public AssemblyParser(params string[] extraAssemblies)
+        {
+            var runtimeAssemblies = Directory.GetFiles(RuntimeEnvironment.GetRuntimeDirectory(), "*.dll");
+            var paths = runtimeAssemblies
+                .Concat(extraAssemblies)
+
+                // TODO find a cleaner way
+                .Append(typeof(JsonSerializer).Assembly.Location)
+                .Append(typeof(RequiredGuidAttribute).Assembly.Location);
+
+
+            var resolver = new PathAssemblyResolver(paths);
+            loadContext = new MetadataLoadContext(resolver);
+        }
+
+
+        public void Dispose()
+        {
+            loadContext.Dispose();
+            GC.SuppressFinalize(this);
+        }
+
+
+        public IEnumerable<IClassTypeExample> GetExamples(Stream assemblyStream)
+        {
+            var assembly = loadContext.LoadFromStream(assemblyStream);
+
+            foreach (var type in assembly.GetTypes().Where(t => t.IsClass))
+                yield return new TypeExample(type);
+        }
+
+
+
+        private class TypeExample : IClassTypeExample
+        {
+            public string AssemblyName => type.Assembly.GetName().Name ?? "";
+            public string? Namespace => type.Namespace;
+            public string ClassName => type.Name;
+
+            private readonly Type type;
+
+
+            public TypeExample(Type type)
+            {
+                this.type = type;
+            }
+
+
+            public string Generate()
+            {
+                /*
+                  We can't create an instance of the type to serialize easily, as most will depend on
+                  assemblies not included in the NuGet package, so we'll parse the Type ourselves.
+                  This is still much easier than using MetadataReader, as we can more easily check against
+                  standard types like Nullable.
+                
+                  The only external dependencies should be the attributes, like [RequiredGuid]. The messaging models
+                  themselves should not inherit from classes outside of their assembly, or include properties
+                  with types from other assemblies. With that assumption, walking the class structure should be safe.
+                  The extraAssemblies passed to TapetiClassLibraryExampleSource can also be used to give it a better chance.
+                */
+                var serialized = TypeToJObjectConverter.Convert(type);
+                return serialized.ToString(Formatting.Indented);
+            }
+        }
+    }
+}

PettingZoo.Tapeti/NuGet/INuGetPackageManager.cs

@@ -0,0 +1,42 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace PettingZoo.Tapeti.NuGet
+{
+    // TODO support logger
+    public interface INuGetPackageManager
+    {
+        public IReadOnlyList<INuGetPackageSource> Sources { get; }
+    }
+
+
+    public interface INuGetPackageSource
+    {
+        public string Name { get; }
+
+        public Task<IReadOnlyList<INuGetPackage>> Search(string searchTerm, bool includePrerelease, CancellationToken cancellationToken);
+    }
+
+
+    public interface INuGetPackage
+    {
+        public string Title { get; }
+        public string Description { get; }
+        public string Authors { get; }
+        public string Version { get; }
+
+        public Task<IReadOnlyList<INuGetPackageVersion>> GetVersions(CancellationToken cancellationToken);
+    }
+    
+
+    public interface INuGetPackageVersion : IComparable<INuGetPackageVersion>
+    {
+        public string Version { get; }
+
+        // TODO support fetching dependencies
+        public Task Download(Stream destination, CancellationToken cancellationToken);
+    }
+}

PettingZoo.Tapeti/NuGet/NuGetPackageManager.cs

@@ -0,0 +1,171 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using System.Xml;
+using NuGet.Common;
+using NuGet.Protocol;
+using NuGet.Protocol.Core.Types;
+using NuGet.Versioning;
+
+namespace PettingZoo.Tapeti.NuGet
+{
+    public class NuGetPackageManager : INuGetPackageManager
+    {
+        private readonly SourceCacheContext cache;
+        private readonly List<Source> sources;
+
+        public IReadOnlyList<INuGetPackageSource> Sources => sources;
+
+
+        public NuGetPackageManager()
+        {
+            cache = new SourceCacheContext();
+            sources = new List<Source>
+            {
+                new(cache, "nuget.org", @"https://api.nuget.org/v3/index.json")
+            };
+        }
+
+
+        public NuGetPackageManager WithSourcesFrom(string nuGetConfig)
+        {
+            if (!File.Exists(nuGetConfig))
+                return this;
+
+            var doc = new XmlDocument();
+            doc.Load(nuGetConfig);
+
+            var nodes = doc.SelectNodes(@"/configuration/packageSources/add");
+            if (nodes == null)
+                return this;
+
+            foreach (var entry in nodes.Cast<XmlNode>())
+            {
+                if (entry.Attributes == null)
+                    continue;
+
+                var nameAttribute = entry.Attributes["key"];
+                var urlAttribute = entry.Attributes["value"];
+
+                if (string.IsNullOrEmpty(nameAttribute?.Value) || string.IsNullOrEmpty(urlAttribute?.Value))
+                    continue;
+
+                sources.Add(new Source(cache, nameAttribute.Value, urlAttribute.Value));
+            }
+
+            return this;
+        }
+
+
+
+        private class Source : INuGetPackageSource
+        {
+            private readonly SourceCacheContext cache;
+            private readonly SourceRepository repository;
+
+            public string Name { get; }
+
+
+            public Source(SourceCacheContext cache, string name, string url)
+            {
+                this.cache = cache;
+                Name = name;
+                repository = Repository.Factory.GetCoreV3(url);
+            }
+
+
+            public async Task<IReadOnlyList<INuGetPackage>> Search(string searchTerm, bool includePrerelease, CancellationToken cancellationToken)
+            {
+                if (string.IsNullOrWhiteSpace(searchTerm))
+                    return Array.Empty<INuGetPackage>();
+
+                var resource = await repository.GetResourceAsync<PackageSearchResource>(cancellationToken);
+                var filter = new SearchFilter(includePrerelease);
+
+                return (await resource.SearchAsync(searchTerm, filter, 0, 20, new NullLogger(),
+                        cancellationToken))
+                    .Select(p => new Package(cache, repository, p))
+                    .ToArray();
+            }
+        }
+
+
+        protected class Package : INuGetPackage
+        {
+            private readonly SourceCacheContext cache;
+            private readonly SourceRepository repository;
+            private readonly IPackageSearchMetadata packageSearchMetadata;
+
+            public string Title => packageSearchMetadata.Title;
+            public string Description => packageSearchMetadata.Description;
+            public string Authors => packageSearchMetadata.Authors;
+            public string Version => packageSearchMetadata.Identity.Version.ToString();
+
+
+            private IReadOnlyList<INuGetPackageVersion>? versions;
+
+
+            public Package(SourceCacheContext cache, SourceRepository repository, IPackageSearchMetadata packageSearchMetadata)
+            {
+                this.cache = cache;
+                this.repository = repository;
+                this.packageSearchMetadata = packageSearchMetadata;
+            }
+
+
+            public async Task<IReadOnlyList<INuGetPackageVersion>> GetVersions(CancellationToken cancellationToken)
+            {
+                return versions ??= (await packageSearchMetadata.GetVersionsAsync())
+                    .Select(v => new PackageVersion(cache, repository, packageSearchMetadata, v.Version))
+                    .ToArray();
+            }
+        }
+
+
+        protected class PackageVersion : INuGetPackageVersion, IComparable<PackageVersion>
+        {
+            private readonly SourceCacheContext cache;
+            private readonly SourceRepository repository;
+            private readonly IPackageSearchMetadata packageSearchMetadata;
+
+            protected readonly NuGetVersion NuGetVersion;
+
+
+            public PackageVersion(SourceCacheContext cache, SourceRepository repository, IPackageSearchMetadata packageSearchMetadata, NuGetVersion nuGetVersion)
+            {
+                this.cache = cache;
+                this.repository = repository;
+                this.packageSearchMetadata = packageSearchMetadata;
+                NuGetVersion = nuGetVersion;
+            }
+
+
+            public string Version => NuGetVersion.ToString();
+
+
+            public async Task Download(Stream destination, CancellationToken cancellationToken)
+            {
+                var resource = await repository.GetResourceAsync<FindPackageByIdResource>(cancellationToken);
+                await resource.CopyNupkgToStreamAsync(packageSearchMetadata.Identity.Id, NuGetVersion, destination, cache, new NullLogger(), cancellationToken);
+            }
+
+
+            public int CompareTo(INuGetPackageVersion? other)
+            {
+                if (ReferenceEquals(this, other)) return 0;
+                if (other == null) return 1;
+
+                return other is PackageVersion packageVersion ? CompareTo(packageVersion) : string.Compare(Version, other.Version, StringComparison.Ordinal);
+            }
+
+            public int CompareTo(PackageVersion? other)
+            {
+                if (ReferenceEquals(this, other)) return 0;
+                return other == null ? 1 : NuGetVersion.CompareTo(other.NuGetVersion);
+            }
+        }
+    }
+}

PettingZoo.Tapeti/PettingZoo.Tapeti.csproj

@@ -1,16 +1,69 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net6.0-windows</TargetFramework>
     <Version>0.1</Version>
+	<UseWpf>true</UseWpf>
+	<Nullable>enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
+    <PackageReference Include="NuGet.Packaging" Version="6.0.0" />
+    <PackageReference Include="NuGet.Protocol" Version="6.0.0" />
+    <PackageReference Include="SharpVectors" Version="1.7.7" />
+    <PackageReference Include="System.ComponentModel.Annotations" Version="5.0.0" />
+    <PackageReference Include="System.Reactive" Version="5.0.0" />
     <PackageReference Include="System.Reflection.MetadataLoadContext" Version="6.0.0" />
+    <PackageReference Include="Tapeti.DataAnnotations.Extensions" Version="3.0.0" />
   </ItemGroup>
 
   <ItemGroup>
     <ProjectReference Include="..\PettingZoo.Core\PettingZoo.Core.csproj" />
+    <ProjectReference Include="..\PettingZoo.WPF\PettingZoo.WPF.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Compile Update="UI\ClassSelection\ClassSelectionStrings.Designer.cs">
+      <DesignTime>True</DesignTime>
+      <AutoGen>True</AutoGen>
+      <DependentUpon>ClassSelectionStrings.resx</DependentUpon>
+    </Compile>
+    <Compile Update="UI\PackageProgress\PackageProgressStrings.Designer.cs">
+      <DesignTime>True</DesignTime>
+      <AutoGen>True</AutoGen>
+      <DependentUpon>PackageProgressStrings.resx</DependentUpon>
+    </Compile>
+    <Compile Update="UI\PackageProgress\PackageProgressWindow.xaml.cs">
+      <SubType>Code</SubType>
+    </Compile>
+    <Compile Update="UI\PackageSelection\PackageSelectionStrings.Designer.cs">
+      <DesignTime>True</DesignTime>
+      <AutoGen>True</AutoGen>
+      <DependentUpon>PackageSelectionStrings.resx</DependentUpon>
+    </Compile>
+  </ItemGroup>
+
+  <ItemGroup>
+    <EmbeddedResource Update="UI\ClassSelection\ClassSelectionStrings.resx">
+      <Generator>PublicResXFileCodeGenerator</Generator>
+      <LastGenOutput>ClassSelectionStrings.Designer.cs</LastGenOutput>
+    </EmbeddedResource>
+    <EmbeddedResource Update="UI\PackageProgress\PackageProgressStrings.resx">
+      <Generator>PublicResXFileCodeGenerator</Generator>
+      <LastGenOutput>PackageProgressStrings.Designer.cs</LastGenOutput>
+    </EmbeddedResource>
+    <EmbeddedResource Update="UI\PackageSelection\PackageSelectionStrings.resx">
+      <Generator>PublicResXFileCodeGenerator</Generator>
+      <LastGenOutput>PackageSelectionStrings.Designer.cs</LastGenOutput>
+    </EmbeddedResource>
+  </ItemGroup>
+
+  <ItemGroup>
+    <Page Update="UI\PackageProgress\PackageProgressWindow.xaml">
+      <XamlRuntime>$(DefaultXamlRuntime)</XamlRuntime>
+      <SubType>Designer</SubType>
+    </Page>
   </ItemGroup>
 
 </Project>

PettingZoo.Tapeti/TapetiClassLibraryExampleGenerator.cs

@@ -0,0 +1,111 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Threading;
+using PettingZoo.Core.Generator;
+using PettingZoo.Core.Settings;
+using PettingZoo.Tapeti.AssemblyLoader;
+using PettingZoo.Tapeti.NuGet;
+using PettingZoo.Tapeti.UI.ClassSelection;
+using PettingZoo.Tapeti.UI.PackageProgress;
+using PettingZoo.Tapeti.UI.PackageSelection;
+
+namespace PettingZoo.Tapeti
+{
+    public class TapetiClassLibraryExampleGenerator : IExampleGenerator
+    {
+        public void Select(object? ownerWindow, Action<IExample> onExampleSelected)
+        {
+            var packageManager = new NuGetPackageManager()
+                .WithSourcesFrom(Path.Combine(PettingZooPaths.InstallationRoot, @"nuget.config"))
+                .WithSourcesFrom(Path.Combine(PettingZooPaths.AppDataRoot, @"nuget.config"));
+
+            var dispatcher = Dispatcher.CurrentDispatcher;
+
+            var viewModel = new PackageSelectionViewModel(packageManager);
+            var selectionWindow = new PackageSelectionWindow(viewModel)
+            {
+                Owner = ownerWindow as Window
+            };
+
+            viewModel.Select += (_, args) =>
+            {
+                dispatcher.Invoke(() =>
+                {
+                    var windowBounds = selectionWindow.RestoreBounds;
+                    selectionWindow.Close();
+
+                    var progressWindow = new PackageProgressWindow();
+                    progressWindow.Left = windowBounds.Left + (windowBounds.Width - progressWindow.Width) / 2;
+                    progressWindow.Left = windowBounds.Top + (windowBounds.Height - progressWindow.Height) / 2;
+                    progressWindow.Show();
+
+                    Task.Run(async () =>
+                    {
+                        try
+                        {
+                            // TODO allow cancelling (by closing the progress window and optionally a Cancel button)
+                            var assemblies = await args.Assemblies.GetAssemblies(progressWindow, CancellationToken.None);
+
+                            // var classes = 
+                            var examples = LoadExamples(assemblies);
+
+                            dispatcher.Invoke(() =>
+                            {
+                                progressWindow.Close();
+                                progressWindow = null;
+
+                                var classSelectionViewModel = new ClassSelectionViewModel(examples);
+                                var classSelectionWindow = new ClassSelectionWindow(classSelectionViewModel)
+                                {
+                                    Top = windowBounds.Top,
+                                    Left = windowBounds.Left,
+                                    Width = windowBounds.Width,
+                                    Height = windowBounds.Height
+                                };
+
+                                classSelectionViewModel.Select += (_, example) =>
+                                {
+                                    classSelectionWindow.Close();
+                                    onExampleSelected(example);
+                                };
+
+                                classSelectionWindow.ShowDialog();
+                            });
+                        }
+                        catch (Exception e)
+                        {
+                            dispatcher.Invoke(() =>
+                            {
+                                // ReSharper disable once ConstantConditionalAccessQualifier - if I remove it, there's a "Dereference of a possibly null reference" warning instead
+                                progressWindow?.Close();
+
+                                MessageBox.Show($"Error while loading assembly: {e.Message}", "Petting Zoo - Exception", MessageBoxButton.OK, MessageBoxImage.Error);
+                            });
+                        }
+                    });
+                });
+            };
+
+            selectionWindow.ShowDialog();
+        }
+
+
+        private static IEnumerable<IClassTypeExample> LoadExamples(IEnumerable<IPackageAssembly> assemblies)
+        {
+            // TODO support folder with additional assemblies to load, or implement a proper NuGet install (with dependencies) instead
+            var assemblyParser = new AssemblyParser.AssemblyParser();
+            return assemblies
+                .SelectMany(a =>
+                {
+                    using var stream = a.GetStream();
+                    return assemblyParser.GetExamples(stream).ToArray();
+                })
+                .ToArray();
+        }
+    }
+}

PettingZoo.Tapeti/TapetiClassLibraryExampleSource.cs

@@ -1,187 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-using System.Reflection;
-using System.Runtime.InteropServices;
-using Newtonsoft.Json;
-using PettingZoo.Core.Generator;
-
-namespace PettingZoo.Tapeti
-{
-    public class TapetiClassLibraryExampleSource : IExampleSource
-    {
-        private readonly string classLibraryFilename;
-        private readonly IEnumerable<string> extraAssemblies;
-        private Lazy<AssemblySource> assemblySource;
-
-
-        public TapetiClassLibraryExampleSource(string classLibraryFilename, IEnumerable<string> extraAssemblies)
-        {
-            this.classLibraryFilename = classLibraryFilename;
-            this.extraAssemblies = extraAssemblies;
-
-            assemblySource = new Lazy<AssemblySource>(AssemblySourceFactory);
-        }
-
-
-        public void Dispose()
-        {
-            if (assemblySource.IsValueCreated)
-                assemblySource.Value.Dispose();
-
-            GC.SuppressFinalize(this);
-        }
-
-
-        public IExampleFolder GetRootFolder()
-        {
-            return assemblySource.Value.RootFolder;
-        }
-
-
-        private AssemblySource AssemblySourceFactory()
-        {
-            var runtimeAssemblies = Directory.GetFiles(RuntimeEnvironment.GetRuntimeDirectory(), "*.dll");
-
-            var paths = runtimeAssemblies
-                .Concat(extraAssemblies)
-                .Append(classLibraryFilename);
-
-            // TODO can we use a custom resolver to detect missing references?
-            var resolver = new PathAssemblyResolver(paths);
-            var loadContext = new MetadataLoadContext(resolver);
-            try
-            {
-                var assembly = loadContext.LoadFromAssemblyPath(classLibraryFilename);
-                var rootFolder = new Folder(@"Root");
-
-
-                foreach (var assemblyType in assembly.GetTypes())
-                    AddType(assemblyType, rootFolder);
-
-
-                return new AssemblySource
-                {
-                    LoadContext = loadContext,
-                    RootFolder = rootFolder
-                };
-            }
-            catch
-            {
-                loadContext.Dispose();
-                throw;
-            }
-        }
-
-
-        private void AddType(Type type, Folder rootFolder)
-        {
-            if (!type.IsClass)
-                return;
-
-            var assemblyName = type.Assembly.GetName().Name + ".";
-            var typeNamespace = type.Namespace ?? "";
-
-            if (typeNamespace.StartsWith(assemblyName))
-                typeNamespace = typeNamespace.Substring(assemblyName.Length);
-
-            var folder = CreateFolder(rootFolder, typeNamespace);
-            folder.AddMessage(new Message(type));
-        }
-
-
-        private static Folder CreateFolder(Folder rootFolder, string typeNamespace)
-        {
-            var parts = typeNamespace.Split('.');
-            if (parts.Length == 0)
-                return rootFolder;
-
-            var folder = rootFolder;
-
-            foreach (var part in parts)
-                folder = folder.CreateFolder(part);
-
-            return folder;
-        }
-
-
-        private class Folder : IExampleFolder
-        {
-            private readonly List<Folder> folders = new();
-            private readonly List<IExampleMessage> messages = new();
-
-
-            public string Name { get; }
-            public IReadOnlyList<IExampleFolder> Folders => folders;
-            public IReadOnlyList<IExampleMessage> Messages => messages;
-
-
-            public Folder(string name)
-            {
-                Name = name;
-            }
-
-
-            public Folder CreateFolder(string name)
-            {
-                var folder = folders.FirstOrDefault(f => f.Name == name);
-                if (folder != null)
-                    return folder;
-
-                folder = new Folder(name);
-                folders.Add(folder);
-                return folder;
-            }
-
-
-            public void AddMessage(IExampleMessage message)
-            {
-                messages.Add(message);
-            }
-        }
-
-
-        private class Message : IExampleMessage
-        {
-            private readonly Type type;
-
-
-            public Message(Type type)
-            {
-                this.type = type;
-            }
-
-
-            public string Generate()
-            {
-                /*
-                  We can't create an instance of the type to serialize easily, as most will depend on
-                  assemblies not included in the NuGet package, so we'll parse the Type ourselves.
-                  This is still much easier than using MetadataReader, as we can more easily check against
-                  standard types like Nullable.
-                
-                  The only external dependencies should be the attributes, like [RequiredGuid]. The messaging models
-                  themselves should not inherit from classes outside of their assembly, or include properties
-                  with types from other assemblies. With that assumption, walking the class structure should be safe.
-                  The extraAssemblies passed to TapetiClassLibraryExampleSource can also be used to give it a better chance.
-                */
-                var serialized = TypeToJObjectConverter.Convert(type);
-                return serialized.ToString(Formatting.Indented);
-            }
-        }
-
-
-        private class AssemblySource : IDisposable
-        {
-            public MetadataLoadContext LoadContext { get; init; }
-            public IExampleFolder RootFolder { get; init; }
-
-
-            public void Dispose()
-            {
-                LoadContext.Dispose();
-            }
-        }
-    }
-}

PettingZoo.Tapeti/TypeToJObjectConverter.cs

@@ -6,7 +6,15 @@ using Newtonsoft.Json.Linq;
 
 namespace PettingZoo.Tapeti
 {
-    internal class TypeToJObjectConverter
+    // TODO detect recursion
+    // TODO detect recursion
+    // TODO detect recursion
+    // TODO stop making nerdy jokes in comments.
+
+    // TODO generate at least one item for enumerables
+    // TODO support basic types
+
+    public class TypeToJObjectConverter
     {
         public static JObject Convert(Type type)
         {
@@ -63,7 +71,7 @@ namespace PettingZoo.Tapeti
             }
 
             if (actualType.IsArray)
-                return new JArray(Convert(actualType.GetElementType()));
+                return new JArray(Convert(actualType.GetElementType()!));
 
             if (actualType.IsEnum)
                 return Enum.GetNames(actualType).FirstOrDefault();

PettingZoo.Tapeti/UI/ClassSelection/ClassSelectionStrings.Designer.cs

@@ -0,0 +1,90 @@
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by a tool.
+//     Runtime Version:4.0.30319.42000
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+namespace PettingZoo.Tapeti.UI.ClassSelection {
+    using System;
+    
+    
+    /// <summary>
+    ///   A strongly-typed resource class, for looking up localized strings, etc.
+    /// </summary>
+    // This class was auto-generated by the StronglyTypedResourceBuilder
+    // class via a tool like ResGen or Visual Studio.
+    // To add or remove a member, edit your .ResX file then rerun ResGen
+    // with the /str option, or rebuild your VS project.
+    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "17.0.0.0")]
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+    [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
+    public class ClassSelectionStrings {
+        
+        private static global::System.Resources.ResourceManager resourceMan;
+        
+        private static global::System.Globalization.CultureInfo resourceCulture;
+        
+        [global::System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
+        internal ClassSelectionStrings() {
+        }
+        
+        /// <summary>
+        ///   Returns the cached ResourceManager instance used by this class.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        public static global::System.Resources.ResourceManager ResourceManager {
+            get {
+                if (object.ReferenceEquals(resourceMan, null)) {
+                    global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("PettingZoo.Tapeti.UI.ClassSelection.ClassSelectionStrings", typeof(ClassSelectionStrings).Assembly);
+                    resourceMan = temp;
+                }
+                return resourceMan;
+            }
+        }
+        
+        /// <summary>
+        ///   Overrides the current thread's CurrentUICulture property for all
+        ///   resource lookups using this strongly typed resource class.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        public static global::System.Globalization.CultureInfo Culture {
+            get {
+                return resourceCulture;
+            }
+            set {
+                resourceCulture = value;
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Cancel.
+        /// </summary>
+        public static string ButtonCancel {
+            get {
+                return ResourceManager.GetString("ButtonCancel", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Select.
+        /// </summary>
+        public static string ButtonSelect {
+            get {
+                return ResourceManager.GetString("ButtonSelect", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Select class.
+        /// </summary>
+        public static string WindowTitle {
+            get {
+                return ResourceManager.GetString("WindowTitle", resourceCulture);
+            }
+        }
+    }
+}

PettingZoo.Tapeti/UI/ClassSelection/ClassSelectionStrings.resx

@@ -0,0 +1,129 @@
+<?xml version="1.0" encoding="utf-8"?>
+<root>
+  <!-- 
+    Microsoft ResX Schema 
+    
+    Version 2.0
+    
+    The primary goals of this format is to allow a simple XML format 
+    that is mostly human readable. The generation and parsing of the 
+    various data types are done through the TypeConverter classes 
+    associated with the data types.
+    
+    Example:
+    
+    ... ado.net/XML headers & schema ...
+    <resheader name="resmimetype">text/microsoft-resx</resheader>
+    <resheader name="version">2.0</resheader>
+    <resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
+    <resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
+    <data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
+    <data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
+    <data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
+        <value>[base64 mime encoded serialized .NET Framework object]</value>
+    </data>
+    <data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
+        <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
+        <comment>This is a comment</comment>
+    </data>
+                
+    There are any number of "resheader" rows that contain simple 
+    name/value pairs.
+    
+    Each data row contains a name, and value. The row also contains a 
+    type or mimetype. Type corresponds to a .NET class that support 
+    text/value conversion through the TypeConverter architecture. 
+    Classes that don't support this are serialized and stored with the 
+    mimetype set.
+    
+    The mimetype is used for serialized objects, and tells the 
+    ResXResourceReader how to depersist the object. This is currently not 
+    extensible. For a given mimetype the value must be set accordingly:
+    
+    Note - application/x-microsoft.net.object.binary.base64 is the format 
+    that the ResXResourceWriter will generate, however the reader can 
+    read any of the formats listed below.
+    
+    mimetype: application/x-microsoft.net.object.binary.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
+            : and then encoded with base64 encoding.
+    
+    mimetype: application/x-microsoft.net.object.soap.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.bytearray.base64
+    value   : The object must be serialized into a byte array 
+            : using a System.ComponentModel.TypeConverter
+            : and then encoded with base64 encoding.
+    -->
+  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
+    <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
+    <xsd:element name="root" msdata:IsDataSet="true">
+      <xsd:complexType>
+        <xsd:choice maxOccurs="unbounded">
+          <xsd:element name="metadata">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" />
+              </xsd:sequence>
+              <xsd:attribute name="name" use="required" type="xsd:string" />
+              <xsd:attribute name="type" type="xsd:string" />
+              <xsd:attribute name="mimetype" type="xsd:string" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="assembly">
+            <xsd:complexType>
+              <xsd:attribute name="alias" type="xsd:string" />
+              <xsd:attribute name="name" type="xsd:string" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="data">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" msdata:Ordinal="1" />
+              <xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
+              <xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="resheader">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" />
+            </xsd:complexType>
+          </xsd:element>
+        </xsd:choice>
+      </xsd:complexType>
+    </xsd:element>
+  </xsd:schema>
+  <resheader name="resmimetype">
+    <value>text/microsoft-resx</value>
+  </resheader>
+  <resheader name="version">
+    <value>2.0</value>
+  </resheader>
+  <resheader name="reader">
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <resheader name="writer">
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <data name="ButtonCancel" xml:space="preserve">
+    <value>Cancel</value>
+  </data>
+  <data name="ButtonSelect" xml:space="preserve">
+    <value>Select</value>
+  </data>
+  <data name="WindowTitle" xml:space="preserve">
+    <value>Select class</value>
+  </data>
+</root>

PettingZoo.Tapeti/UI/ClassSelection/ClassSelectionViewModel.cs

@@ -0,0 +1,211 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Linq;
+using System.Windows.Input;
+using PettingZoo.Core.Generator;
+using PettingZoo.WPF.ViewModel;
+
+namespace PettingZoo.Tapeti.UI.ClassSelection
+{
+    public class ClassSelectionViewModel : BaseViewModel
+    {
+        private BaseClassTreeItem? selectedItem;
+        private readonly DelegateCommand selectCommand;
+
+        public ObservableCollection<BaseClassTreeItem> Examples { get; } = new();
+
+        public BaseClassTreeItem? SelectedItem
+        {
+            get => selectedItem; 
+            set
+            {
+                if (!SetField(ref selectedItem, value))
+                    return;
+
+                selectCommand.RaiseCanExecuteChanged();
+            }
+        }
+
+
+        public ICommand SelectCommand => selectCommand;
+
+
+        public event EventHandler<IExample>? Select;
+
+
+        public ClassSelectionViewModel(IEnumerable<IClassTypeExample> examples)
+        {
+            selectCommand = new DelegateCommand(SelectExecute, SelectCanExecute);
+
+            TreeFromExamples(examples);
+        }
+
+
+        private void SelectExecute()
+        {
+            if (SelectedItem is not ExampleTreeItem exampleTreeItem)
+                return;
+
+            Select?.Invoke(this, exampleTreeItem.Example);
+        }
+
+
+        private bool SelectCanExecute()
+        {
+            return SelectedItem is ExampleTreeItem;
+        }
+
+
+        private void TreeFromExamples(IEnumerable<IClassTypeExample> examples)
+        {
+            var root = new NamespaceFolderClassTreeItem(string.Empty);
+
+            foreach (var example in examples)
+            {
+                var folder = !string.IsNullOrEmpty(example.Namespace) 
+                    ? CreateFolder(root, example.Namespace.Split('.'))
+                    : root;
+
+                folder.AddChild(new ExampleTreeItem(example));
+            }
+            
+
+            // If the first levels only consist of one child folder, collapse them into one entry
+            var collapsedRoot = root;
+            while (collapsedRoot.Children.Count == 1 && collapsedRoot.Children.First() is NamespaceFolderClassTreeItem newRoot)
+                collapsedRoot = newRoot.Collapse(collapsedRoot.Name);
+
+            if (ReferenceEquals(collapsedRoot, root))
+            {
+                foreach (var rootItem in root.Children)
+                    Examples.Add(rootItem);
+            }
+            else
+                Examples.Add(collapsedRoot);
+        }
+
+
+        private static NamespaceFolderClassTreeItem CreateFolder(NamespaceFolderClassTreeItem root, IEnumerable<string> parts)
+        {
+            var parent = root;
+
+            foreach (var part in parts)
+            {
+                if (parent.Children.FirstOrDefault(c => c is NamespaceFolderClassTreeItem && c.Name == part) is NamespaceFolderClassTreeItem child)
+                {
+                    parent = child;
+                    continue;
+                }
+
+                child = new NamespaceFolderClassTreeItem(part);
+                parent.AddChild(child);
+
+                parent = child;
+            }
+
+            return parent;
+        }
+    }
+
+
+    public class BaseClassTreeItem
+    {
+        private readonly SortedSet<BaseClassTreeItem> children = new(new BaseClassTreeItemComparer());
+
+        public string Name { get; protected set; }
+        public IReadOnlyCollection<BaseClassTreeItem> Children => children;
+
+
+        public BaseClassTreeItem(string name)
+        {
+            Name = name;
+        }
+
+
+        public void AddChild(BaseClassTreeItem item)
+        {
+            children.Add(item);
+        }
+    }
+
+
+    public class NamespaceFolderClassTreeItem : BaseClassTreeItem
+    {
+        public NamespaceFolderClassTreeItem(string name) : base(name)
+        {
+        }
+
+
+        public NamespaceFolderClassTreeItem Collapse(string parentFolderName)
+        {
+            Name = string.IsNullOrEmpty(parentFolderName) ? Name : parentFolderName + "." + Name;
+            return this;
+        }
+    }
+
+
+    public class ExampleTreeItem : BaseClassTreeItem
+    {
+        public IClassTypeExample Example { get; }
+
+
+        public ExampleTreeItem(IClassTypeExample example) : base(example.ClassName)
+        {
+            Example = example;
+        }
+    }
+
+
+    public class BaseClassTreeItemComparer : IComparer<BaseClassTreeItem>
+    {
+        public int Compare(BaseClassTreeItem? x, BaseClassTreeItem? y)
+        {
+            if (ReferenceEquals(x, y)) return 0;
+            if (y == null) return 1;
+            if (x == null) return -1;
+
+            if (x.GetType() != y.GetType())
+                return x is NamespaceFolderClassTreeItem ? -1 : 1;
+
+            return string.Compare(x.Name, y.Name, StringComparison.Ordinal);
+        }
+    }
+
+
+    public class DesignTimeClassSelectionViewModel : ClassSelectionViewModel
+    {
+        public DesignTimeClassSelectionViewModel() 
+            : base(new IClassTypeExample[]
+            {
+                new DesignTimeExample("Messaging.Test", "Messaging.Test", "TestMessage"),
+                new DesignTimeExample("Messaging.Test", "Messaging.Test", "SomeRequestMessage"),
+                new DesignTimeExample("Messaging.Test", "Messaging.Test.Model", "SomeViewModel")
+            })
+        {
+
+        }
+
+
+        private class DesignTimeExample : IClassTypeExample
+        {
+            public string AssemblyName { get; }
+            public string? Namespace { get; }
+            public string ClassName { get; }
+
+
+            public DesignTimeExample(string assemblyName, string? ns, string className)
+            {
+                AssemblyName = assemblyName;
+                Namespace = ns;
+                ClassName = className;
+            }
+
+
+            public string Generate()
+            {
+                return "";
+            }
+        }
+    }
+}

PettingZoo.Tapeti/UI/ClassSelection/ClassSelectionWindow.xaml

@@ -0,0 +1,69 @@
+<Window x:Class="PettingZoo.Tapeti.UI.ClassSelection.ClassSelectionWindow"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
+        xmlns:controls="clr-namespace:PettingZoo.WPF.Controls;assembly=PettingZoo.WPF"
+        xmlns:classSelection="clr-namespace:PettingZoo.Tapeti.UI.ClassSelection"
+        xmlns:svgc="http://sharpvectors.codeplex.com/svgc/"
+        mc:Ignorable="d" 
+        Title="{x:Static classSelection:ClassSelectionStrings.WindowTitle}" 
+        Height="600" 
+        Width="800"
+        ResizeMode="CanResizeWithGrip"
+        WindowStartupLocation="CenterOwner"
+        d:DataContext="{d:DesignInstance classSelection:DesignTimeClassSelectionViewModel, IsDesignTimeCreatable=True}">
+    <Window.Resources>
+        <ResourceDictionary>
+            <Style x:Key="TreeItemIcon" TargetType="{x:Type Image}">
+                <Setter Property="Margin" Value="2,2,8,2" />
+            </Style>
+
+            <Style x:Key="TreeItemLabel" TargetType="{x:Type TextBlock}">
+                <Setter Property="VerticalAlignment" Value="Center" />
+            </Style>
+
+            <ResourceDictionary.MergedDictionaries>
+                <ResourceDictionary Source="pack://application:,,,/PettingZoo.WPF;component/Style.xaml"/>
+            </ResourceDictionary.MergedDictionaries>
+        </ResourceDictionary>
+    </Window.Resources>
+
+    <controls:GridLayout Style="{StaticResource Form}" Margin="8">
+        <Grid.RowDefinitions>
+            <RowDefinition Height="*" />
+            <RowDefinition Height="Auto" />
+        </Grid.RowDefinitions>
+
+        <TreeView Grid.Row="0" ItemsSource="{Binding Examples}" SelectedItemChanged="TreeView_OnSelectedItemChanged">
+            <TreeView.ItemContainerStyle>
+                <Style TargetType="{x:Type TreeViewItem}">
+                    <Setter Property="IsExpanded" Value="True" />
+                </Style>
+            </TreeView.ItemContainerStyle>
+            <TreeView.Resources>
+                <HierarchicalDataTemplate DataType="{x:Type classSelection:NamespaceFolderClassTreeItem}" ItemsSource="{Binding Children}">
+                    <StackPanel Orientation="Horizontal">
+                        <!-- 
+                            I couldn't get the image assets to work from within this assembly, so I've simply included them in the main application. 
+                            Not pretty, and it still doesn't show up in design-time, but works at runtime for now. 
+                        -->
+                        <Image Source="{svgc:SvgImage Source=/Images/Folder.svg, AppName=PettingZoo}" Width="16" Height="16" Style="{StaticResource TreeItemIcon}"/>
+                        <TextBlock Text="{Binding Name}" Style="{StaticResource TreeItemLabel}" />
+                    </StackPanel>
+                </HierarchicalDataTemplate>
+                <HierarchicalDataTemplate DataType="{x:Type classSelection:ExampleTreeItem}">
+                    <StackPanel Orientation="Horizontal">
+                        <Image Source="{svgc:SvgImage Source=/Images/Example.svg, AppName=PettingZoo}" Width="16" Height="16" Style="{StaticResource TreeItemIcon}"/>
+                        <TextBlock Text="{Binding Name}" Style="{StaticResource TreeItemLabel}" />
+                    </StackPanel>
+                </HierarchicalDataTemplate>
+            </TreeView.Resources>
+        </TreeView>
+
+        <StackPanel Grid.Row="1" Orientation="Horizontal" HorizontalAlignment="Right" Style="{StaticResource FooterPanel}">
+            <Button Content="{x:Static classSelection:ClassSelectionStrings.ButtonSelect}" Style="{StaticResource FooterButton}" Command="{Binding SelectCommand}" />
+            <Button Content="{x:Static classSelection:ClassSelectionStrings.ButtonCancel}"  Style="{StaticResource FooterButton}" />
+        </StackPanel>
+    </controls:GridLayout>
+</Window>

PettingZoo.Tapeti/UI/ClassSelection/ClassSelectionWindow.xaml.cs

@@ -0,0 +1,27 @@
+using System.Windows;
+
+namespace PettingZoo.Tapeti.UI.ClassSelection
+{
+    /// <summary>
+    /// Interaction logic for ClassSelectionWindow.xaml
+    /// </summary>
+    public partial class ClassSelectionWindow
+    {
+        private readonly ClassSelectionViewModel viewModel;
+
+
+        public ClassSelectionWindow(ClassSelectionViewModel viewModel)
+        {
+            this.viewModel = viewModel;
+
+            DataContext = viewModel;
+            InitializeComponent();
+        }
+
+
+        private void TreeView_OnSelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
+        {
+            viewModel.SelectedItem = (BaseClassTreeItem)e.NewValue;
+        }
+    }
+}

PettingZoo.Tapeti/UI/PackageProgress/PackageProgressStrings.Designer.cs

@@ -8,7 +8,7 @@
 // </auto-generated>
 //------------------------------------------------------------------------------
 
-namespace PettingZoo.UI.Example {
+namespace PettingZoo.Tapeti.UI.PackageProgress {
     using System;
     
     
@@ -22,14 +22,14 @@ namespace PettingZoo.UI.Example {
     [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "17.0.0.0")]
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
     [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
-    public class ExamplePickerDialogStrings {
+    public class PackageProgressStrings {
         
         private static global::System.Resources.ResourceManager resourceMan;
         
         private static global::System.Globalization.CultureInfo resourceCulture;
         
         [global::System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
-        internal ExamplePickerDialogStrings() {
+        internal PackageProgressStrings() {
         }
         
         /// <summary>
@@ -39,7 +39,7 @@ namespace PettingZoo.UI.Example {
         public static global::System.Resources.ResourceManager ResourceManager {
             get {
                 if (object.ReferenceEquals(resourceMan, null)) {
-                    global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("PettingZoo.UI.Example.ExamplePickerDialogStrings", typeof(ExamplePickerDialogStrings).Assembly);
+                    global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("PettingZoo.Tapeti.UI.PackageProgress.PackageProgressStrings", typeof(PackageProgressStrings).Assembly);
                     resourceMan = temp;
                 }
                 return resourceMan;
@@ -61,7 +61,7 @@ namespace PettingZoo.UI.Example {
         }
         
         /// <summary>
-        ///   Looks up a localized string similar to Select example.
+        ///   Looks up a localized string similar to Reading message classes....
         /// </summary>
         public static string WindowTitle {
             get {

PettingZoo.Tapeti/UI/PackageProgress/PackageProgressStrings.resx

@@ -118,6 +118,6 @@
     <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
   </resheader>
   <data name="WindowTitle" xml:space="preserve">
-    <value>Select example</value>
+    <value>Reading message classes...</value>
   </data>
 </root>

PettingZoo.Tapeti/UI/PackageProgress/PackageProgressWindow.xaml

@@ -0,0 +1,14 @@
+<Window x:Class="PettingZoo.Tapeti.UI.PackageProgress.PackageProgressWindow"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        xmlns:packageProgress="clr-namespace:PettingZoo.Tapeti.UI.PackageProgress"
+        mc:Ignorable="d" 
+        Height="80" 
+        Width="400"
+        Title="{x:Static packageProgress:PackageProgressStrings.WindowTitle}" 
+        ResizeMode="NoResize"
+        WindowStyle="ToolWindow">
+    <ProgressBar Height="25" Margin="16" VerticalAlignment="Center" Name="Progress" Maximum="100" />
+</Window>

PettingZoo.Tapeti/UI/PackageProgress/PackageProgressWindow.xaml.cs

@@ -0,0 +1,24 @@
+using System;
+
+namespace PettingZoo.Tapeti.UI.PackageProgress
+{
+    /// <summary>
+    /// Interaction logic for PackageProgressWindow.xaml
+    /// </summary>
+    public partial class PackageProgressWindow : IProgress<int>
+    {
+        public PackageProgressWindow()
+        {
+            InitializeComponent();
+        }
+
+
+        public void Report(int value)
+        {
+            Dispatcher.BeginInvoke(() =>
+            {
+                Progress.Value = value;
+            });
+        }
+    }
+}

PettingZoo.Tapeti/UI/PackageSelection/PackageSelectionStrings.Designer.cs

@@ -0,0 +1,171 @@
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by a tool.
+//     Runtime Version:4.0.30319.42000
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+namespace PettingZoo.Tapeti.UI.PackageSelection {
+    using System;
+    
+    
+    /// <summary>
+    ///   A strongly-typed resource class, for looking up localized strings, etc.
+    /// </summary>
+    // This class was auto-generated by the StronglyTypedResourceBuilder
+    // class via a tool like ResGen or Visual Studio.
+    // To add or remove a member, edit your .ResX file then rerun ResGen
+    // with the /str option, or rebuild your VS project.
+    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "17.0.0.0")]
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+    [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
+    public class PackageSelectionStrings {
+        
+        private static global::System.Resources.ResourceManager resourceMan;
+        
+        private static global::System.Globalization.CultureInfo resourceCulture;
+        
+        [global::System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]
+        internal PackageSelectionStrings() {
+        }
+        
+        /// <summary>
+        ///   Returns the cached ResourceManager instance used by this class.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        public static global::System.Resources.ResourceManager ResourceManager {
+            get {
+                if (object.ReferenceEquals(resourceMan, null)) {
+                    global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("PettingZoo.Tapeti.UI.PackageSelection.PackageSelectionStrings", typeof(PackageSelectionStrings).Assembly);
+                    resourceMan = temp;
+                }
+                return resourceMan;
+            }
+        }
+        
+        /// <summary>
+        ///   Overrides the current thread's CurrentUICulture property for all
+        ///   resource lookups using this strongly typed resource class.
+        /// </summary>
+        [global::System.ComponentModel.EditorBrowsableAttribute(global::System.ComponentModel.EditorBrowsableState.Advanced)]
+        public static global::System.Globalization.CultureInfo Culture {
+            get {
+                return resourceCulture;
+            }
+            set {
+                resourceCulture = value;
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Assembly files (*.dll)|*.dll|All files (*.*)|*.*.
+        /// </summary>
+        public static string AssemblyFileFilter {
+            get {
+                return ResourceManager.GetString("AssemblyFileFilter", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Browse....
+        /// </summary>
+        public static string ButtonBrowse {
+            get {
+                return ResourceManager.GetString("ButtonBrowse", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Cancel.
+        /// </summary>
+        public static string ButtonCancel {
+            get {
+                return ResourceManager.GetString("ButtonCancel", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Select.
+        /// </summary>
+        public static string ButtonSelect {
+            get {
+                return ResourceManager.GetString("ButtonSelect", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Include prerelease.
+        /// </summary>
+        public static string CheckPrerelease {
+            get {
+                return ResourceManager.GetString("CheckPrerelease", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to You can add extra NuGet feeds by placing a standard nuget.config file in PettingZoo&apos;s installation directory &quot;{0}&quot; or in &quot;{1}&quot;.
+        /// </summary>
+        public static string HintNuGetSources {
+            get {
+                return ResourceManager.GetString("HintNuGetSources", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Version.
+        /// </summary>
+        public static string LabelVersion {
+            get {
+                return ResourceManager.GetString("LabelVersion", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Loading....
+        /// </summary>
+        public static string Loading {
+            get {
+                return ResourceManager.GetString("Loading", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Search....
+        /// </summary>
+        public static string PlaceholderNuGetSearch {
+            get {
+                return ResourceManager.GetString("PlaceholderNuGetSearch", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Load from assembly file.
+        /// </summary>
+        public static string RadioAssembly {
+            get {
+                return ResourceManager.GetString("RadioAssembly", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Load from NuGet package.
+        /// </summary>
+        public static string RadioNuGet {
+            get {
+                return ResourceManager.GetString("RadioNuGet", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Select source.
+        /// </summary>
+        public static string WindowTitle {
+            get {
+                return ResourceManager.GetString("WindowTitle", resourceCulture);
+            }
+        }
+    }
+}

PettingZoo.Tapeti/UI/PackageSelection/PackageSelectionStrings.resx

@@ -0,0 +1,156 @@
+<?xml version="1.0" encoding="utf-8"?>
+<root>
+  <!-- 
+    Microsoft ResX Schema 
+    
+    Version 2.0
+    
+    The primary goals of this format is to allow a simple XML format 
+    that is mostly human readable. The generation and parsing of the 
+    various data types are done through the TypeConverter classes 
+    associated with the data types.
+    
+    Example:
+    
+    ... ado.net/XML headers & schema ...
+    <resheader name="resmimetype">text/microsoft-resx</resheader>
+    <resheader name="version">2.0</resheader>
+    <resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
+    <resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
+    <data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
+    <data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
+    <data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
+        <value>[base64 mime encoded serialized .NET Framework object]</value>
+    </data>
+    <data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
+        <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
+        <comment>This is a comment</comment>
+    </data>
+                
+    There are any number of "resheader" rows that contain simple 
+    name/value pairs.
+    
+    Each data row contains a name, and value. The row also contains a 
+    type or mimetype. Type corresponds to a .NET class that support 
+    text/value conversion through the TypeConverter architecture. 
+    Classes that don't support this are serialized and stored with the 
+    mimetype set.
+    
+    The mimetype is used for serialized objects, and tells the 
+    ResXResourceReader how to depersist the object. This is currently not 
+    extensible. For a given mimetype the value must be set accordingly:
+    
+    Note - application/x-microsoft.net.object.binary.base64 is the format 
+    that the ResXResourceWriter will generate, however the reader can 
+    read any of the formats listed below.
+    
+    mimetype: application/x-microsoft.net.object.binary.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
+            : and then encoded with base64 encoding.
+    
+    mimetype: application/x-microsoft.net.object.soap.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.bytearray.base64
+    value   : The object must be serialized into a byte array 
+            : using a System.ComponentModel.TypeConverter
+            : and then encoded with base64 encoding.
+    -->
+  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
+    <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
+    <xsd:element name="root" msdata:IsDataSet="true">
+      <xsd:complexType>
+        <xsd:choice maxOccurs="unbounded">
+          <xsd:element name="metadata">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" />
+              </xsd:sequence>
+              <xsd:attribute name="name" use="required" type="xsd:string" />
+              <xsd:attribute name="type" type="xsd:string" />
+              <xsd:attribute name="mimetype" type="xsd:string" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="assembly">
+            <xsd:complexType>
+              <xsd:attribute name="alias" type="xsd:string" />
+              <xsd:attribute name="name" type="xsd:string" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="data">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" msdata:Ordinal="1" />
+              <xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
+              <xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="resheader">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" />
+            </xsd:complexType>
+          </xsd:element>
+        </xsd:choice>
+      </xsd:complexType>
+    </xsd:element>
+  </xsd:schema>
+  <resheader name="resmimetype">
+    <value>text/microsoft-resx</value>
+  </resheader>
+  <resheader name="version">
+    <value>2.0</value>
+  </resheader>
+  <resheader name="reader">
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <resheader name="writer">
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <data name="AssemblyFileFilter" xml:space="preserve">
+    <value>Assembly files (*.dll)|*.dll|All files (*.*)|*.*</value>
+  </data>
+  <data name="ButtonBrowse" xml:space="preserve">
+    <value>Browse...</value>
+  </data>
+  <data name="ButtonCancel" xml:space="preserve">
+    <value>Cancel</value>
+  </data>
+  <data name="ButtonSelect" xml:space="preserve">
+    <value>Select</value>
+  </data>
+  <data name="CheckPrerelease" xml:space="preserve">
+    <value>Include prerelease</value>
+  </data>
+  <data name="HintNuGetSources" xml:space="preserve">
+    <value>You can add extra NuGet feeds by placing a standard nuget.config file in PettingZoo's installation directory "{0}" or in "{1}"</value>
+  </data>
+  <data name="LabelVersion" xml:space="preserve">
+    <value>Version</value>
+  </data>
+  <data name="Loading" xml:space="preserve">
+    <value>Loading...</value>
+  </data>
+  <data name="PlaceholderNuGetSearch" xml:space="preserve">
+    <value>Search...</value>
+  </data>
+  <data name="RadioAssembly" xml:space="preserve">
+    <value>Load from assembly file</value>
+  </data>
+  <data name="RadioNuGet" xml:space="preserve">
+    <value>Load from NuGet package</value>
+  </data>
+  <data name="WindowTitle" xml:space="preserve">
+    <value>Select source</value>
+  </data>
+</root>

PettingZoo.Tapeti/UI/PackageSelection/PackageSelectionViewModel.cs

@@ -0,0 +1,418 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Reactive.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Input;
+using Microsoft.Win32;
+using PettingZoo.Core.Settings;
+using PettingZoo.Tapeti.AssemblyLoader;
+using PettingZoo.Tapeti.NuGet;
+using PettingZoo.WPF.ViewModel;
+
+namespace PettingZoo.Tapeti.UI.PackageSelection
+{
+    public enum PackageSelectionSource
+    {
+        Assembly,
+        NuGet
+    }
+
+
+    public class PackageSelectionViewModel : BaseViewModel
+    {
+        private readonly INuGetPackageManager nuGetPackageManager;
+
+        private readonly DelegateCommand selectCommand;
+
+        private PackageSelectionSource packageSelectionSource = PackageSelectionSource.Assembly;
+        private string assemblyFilename = "";
+        private readonly DelegateCommand assemblyBrowse;
+
+        private string nuGetSearchTerm = "";
+        private bool nuGetIncludePrerelease;
+        private INuGetPackageSource? selectedNuGetSource;
+        private INuGetPackage? selectedPackage;
+        private INuGetPackageVersion? selectedVersion;
+
+        private string packagesStatus = "";
+        private Visibility packagesStatusVisibility = Visibility.Collapsed;
+
+
+        public ICommand SelectCommand => selectCommand;
+
+
+        public PackageSelectionSource PackageSelectionSource
+        {
+            get => packageSelectionSource;
+            set => SetField(ref packageSelectionSource, value, otherPropertiesChanged: new[] { nameof(PackageSelectionSourceAssembly), nameof(PackageSelectionSourceNuGet) });
+        }
+
+
+        public bool PackageSelectionSourceAssembly
+        {
+            get => PackageSelectionSource == PackageSelectionSource.Assembly;
+            set
+            {
+                if (value)
+                    PackageSelectionSource = PackageSelectionSource.Assembly;
+            }
+        }
+
+        public bool PackageSelectionSourceNuGet
+        {
+            get => PackageSelectionSource == PackageSelectionSource.NuGet;
+            set
+            {
+                if (value)
+                    PackageSelectionSource = PackageSelectionSource.NuGet;
+            }
+        }
+
+
+        public string AssemblyFilename
+        {
+            get => assemblyFilename;
+            set
+            {
+                if (!SetField(ref assemblyFilename, value))
+                    return;
+
+                if (!string.IsNullOrEmpty(value))
+                    PackageSelectionSource = PackageSelectionSource.Assembly;
+            }
+        }
+
+        public ICommand AssemblyBrowse => assemblyBrowse;
+
+
+        public static string HintNuGetSources => string.Format(PackageSelectionStrings.HintNuGetSources, PettingZooPaths.InstallationRoot, PettingZooPaths.AppDataRoot);
+
+        public string NuGetSearchTerm
+        {
+            get => nuGetSearchTerm;
+            set
+            {
+                if (!SetField(ref nuGetSearchTerm, value, otherPropertiesChanged: new[] { nameof(NuGetSearchTermPlaceholderVisibility) }))
+                    return;
+
+                if (!string.IsNullOrEmpty(value))
+                    PackageSelectionSource = PackageSelectionSource.NuGet;
+            }
+        }
+
+        public bool NuGetIncludePrerelease
+        {
+            get => nuGetIncludePrerelease;
+            set => SetField(ref nuGetIncludePrerelease, value);
+        }
+
+        public Visibility NuGetSearchTermPlaceholderVisibility => string.IsNullOrEmpty(NuGetSearchTerm) ? Visibility.Visible : Visibility.Hidden;
+        public IReadOnlyList<INuGetPackageSource> NuGetSources => nuGetPackageManager.Sources;
+
+        public INuGetPackageSource? SelectedNuGetSource
+        {
+            get => selectedNuGetSource;
+            set
+            {
+                if (!SetField(ref selectedNuGetSource, value))
+                    return;
+
+                Packages.Clear();
+                SelectedPackage = null;
+            }
+        }
+
+        public ObservableCollectionEx<INuGetPackage> Packages { get; } = new();
+        public ObservableCollectionEx<INuGetPackageVersion> Versions { get; } = new();
+
+
+        public string PackagesStatus
+        {
+            get => packagesStatus;
+            set => SetField(ref packagesStatus, value);
+        }
+
+
+        public Visibility PackagesStatusVisibility
+        {
+            get => packagesStatusVisibility;
+            set => SetField(ref packagesStatusVisibility, value);
+        }
+
+
+        public INuGetPackage? SelectedPackage
+        {
+            get => selectedPackage;
+            set
+            {
+                if (!SetField(ref selectedPackage, value))
+                    return;
+
+                Versions.Clear();
+                SelectedVersion = null;
+            }
+        }
+
+
+        public INuGetPackageVersion? SelectedVersion
+        {
+            get => selectedVersion;
+            set => SetField(ref selectedVersion, value);
+        }
+
+
+        public class SelectPackageEventArgs
+        {
+            public IPackageAssemblies Assemblies { get; }
+
+
+            public SelectPackageEventArgs(IPackageAssemblies assemblies)
+            {
+                Assemblies = assemblies;
+            }
+        }
+
+
+        public event EventHandler<SelectPackageEventArgs>? Select;
+
+
+        public PackageSelectionViewModel(INuGetPackageManager nuGetPackageManager)
+        {
+            this.nuGetPackageManager = nuGetPackageManager;
+
+            selectCommand = new DelegateCommand(SelectExecute, SelectCanExecute);
+
+            assemblyBrowse = new DelegateCommand(AssemblyBrowseExecute);
+
+
+            // TODO remember source
+            if (nuGetPackageManager.Sources.Count > 0)
+                selectedNuGetSource = nuGetPackageManager.Sources[^1];
+
+            var propertyChangedObservable = Observable.FromEventPattern<PropertyChangedEventHandler, PropertyChangedEventArgs>(
+                    h => PropertyChanged += h,
+                    h => PropertyChanged -= h);
+
+            propertyChangedObservable
+                .Where(e => e.EventArgs.PropertyName is nameof(NuGetSearchTerm) or nameof(NuGetIncludePrerelease) or nameof(SelectedNuGetSource))
+                .Throttle(TimeSpan.FromMilliseconds(500))
+                .ObserveOn(SynchronizationContext.Current!)
+                .Subscribe(_ => NuGetSearch());
+
+            propertyChangedObservable
+                .Where(e => e.EventArgs.PropertyName == nameof(SelectedPackage))
+                .Throttle(TimeSpan.FromMilliseconds(100))
+                .ObserveOn(SynchronizationContext.Current!)
+                .Subscribe(_ => NuGetGetVersions());
+
+
+            propertyChangedObservable
+                .Where(e => e.EventArgs.PropertyName is nameof(PackageSelectionSource) or nameof(AssemblyFilename) or nameof(SelectedVersion))
+                .ObserveOn(SynchronizationContext.Current!)
+                .Subscribe(_ => selectCommand.RaiseCanExecuteChanged());
+        }
+
+
+        private void SelectExecute()
+        {
+            IPackageAssemblies? assemblies = PackageSelectionSource switch
+            {
+                PackageSelectionSource.Assembly => !string.IsNullOrWhiteSpace(AssemblyFilename) ? new FilePackageAssemblies(AssemblyFilename) : null,
+                PackageSelectionSource.NuGet => SelectedVersion != null ? new NuGetPackageAssemblies(SelectedVersion) : null,
+                _ => throw new ArgumentOutOfRangeException()
+            };
+            
+            if (assemblies != null)
+                Select?.Invoke(this, new SelectPackageEventArgs(assemblies));
+        }
+
+
+        private bool SelectCanExecute()
+        {
+            return PackageSelectionSource switch
+            {
+                PackageSelectionSource.Assembly => !string.IsNullOrWhiteSpace(AssemblyFilename),
+                PackageSelectionSource.NuGet => SelectedVersion != null,
+                _ => false
+            };
+        }
+
+
+        private void AssemblyBrowseExecute()
+        {
+            var dialog = new OpenFileDialog
+            {
+                CheckFileExists = true,
+                Filter = PackageSelectionStrings.AssemblyFileFilter
+            };
+
+            if (!dialog.ShowDialog().GetValueOrDefault())
+                return;
+
+            AssemblyFilename = dialog.FileName;
+        }
+
+
+        private CancellationTokenSource? nuGetSearchCancellationTokenSource;
+
+        private void NuGetSearch()
+        {
+            if (SelectedNuGetSource == null)
+                return;
+
+            nuGetSearchCancellationTokenSource?.Cancel();
+
+            nuGetSearchCancellationTokenSource = new CancellationTokenSource();
+            var cancellationToken = nuGetSearchCancellationTokenSource.Token;
+
+            var source = SelectedNuGetSource;
+            var searchTerm = NuGetSearchTerm;
+            var includePrerelease = NuGetIncludePrerelease;
+
+            SelectedPackage = null;
+            Packages.Clear();
+
+            PackagesStatus = PackageSelectionStrings.Loading;
+            PackagesStatusVisibility = Visibility.Visible;
+
+            Task.Run(async () =>
+            {
+                try
+                {
+                    var packages = await source.Search(searchTerm, includePrerelease, cancellationToken);
+
+                    await Application.Current.Dispatcher.BeginInvoke(() =>
+                    {
+                        Packages.ReplaceAll(packages);
+                        SelectedPackage = null;
+
+                        PackagesStatus = "";
+                        PackagesStatusVisibility = Visibility.Collapsed;
+
+                        Versions.Clear();
+                        SelectedVersion = null;
+                    });
+                }
+                catch (OperationCanceledException)
+                {
+                    // By design...
+                }
+                catch (Exception e)
+                {
+                    PackagesStatus = e.Message;
+                    PackagesStatusVisibility = Visibility.Visible;
+                }
+            }, CancellationToken.None);
+        }
+
+
+        private CancellationTokenSource? nuGetGetVersionsCancellationTokenSource;
+
+        private void NuGetGetVersions()
+        {
+            if (SelectedPackage == null)
+                return;
+
+            nuGetGetVersionsCancellationTokenSource?.Cancel();
+
+            nuGetGetVersionsCancellationTokenSource = new CancellationTokenSource();
+            var cancellationToken = nuGetGetVersionsCancellationTokenSource.Token;
+
+            var package = SelectedPackage;
+
+            Task.Run(async () =>
+            {
+                try
+                {
+                    var versions = await package.GetVersions(cancellationToken);
+
+                    if (cancellationToken.IsCancellationRequested)
+                        return;
+
+                    await Application.Current.Dispatcher.BeginInvoke(() =>
+                    {
+                        if (cancellationToken.IsCancellationRequested)
+                            return;
+
+                        Versions.ReplaceAll(versions);
+                        SelectedVersion = versions.Count > 0 ? versions[0] : null;
+                    });
+                }
+                catch (OperationCanceledException)
+                {
+                    // By design...
+                }
+            }, CancellationToken.None);
+        }
+    }
+
+
+    public class DesignTimePackageSelectionViewModel : PackageSelectionViewModel
+    {
+        public DesignTimePackageSelectionViewModel() : base(new DesignTimeNuGetPackageManager())
+        {
+            Packages.ReplaceAll(new []
+            {
+                new DesignTimeNuGetPackage("Tapeti", "Shameless plug", "M. van Renswoude", "2.8"),
+                new DesignTimeNuGetPackage("Messaging.Example", "Some messaging package with a very long description to test the text trimming. It should be very very very very very very very very very very very long indeed.", "Anonymoose", "0.9")
+            });
+
+            PackagesStatus = @"This is a very long status message, which is not unreasonable since exceptions can occur while fetching NuGet packages and they will be displayed here.";
+            PackagesStatusVisibility = Visibility.Visible;
+        }
+
+
+        private class DesignTimeNuGetPackageManager : INuGetPackageManager
+        {
+            public IReadOnlyList<INuGetPackageSource> Sources { get; } = new[]
+            {
+                new DesignTimeNuGetPackageSource("nuget.org")
+            };
+        }
+
+
+        private class DesignTimeNuGetPackageSource : INuGetPackageSource
+        {
+            public string Name { get; }
+
+
+            public DesignTimeNuGetPackageSource(string name)
+            {
+                Name = name;
+            }
+
+
+            public Task<IReadOnlyList<INuGetPackage>> Search(string searchTerm, bool includePrerelease, CancellationToken cancellationToken)
+            {
+                return Task.FromResult(Array.Empty<INuGetPackage>() as IReadOnlyList<INuGetPackage>);
+            }
+        }
+
+
+        private class DesignTimeNuGetPackage : INuGetPackage
+        {
+            public string Title { get; }
+            public string Description { get; }
+            public string Authors { get; }
+            public string Version { get; }
+
+
+            public DesignTimeNuGetPackage(string title, string description, string authors, string version)
+            {
+                Title = title;
+                Description = description;
+                Authors = authors;
+                Version = version;
+            }
+
+
+            public Task<IReadOnlyList<INuGetPackageVersion>> GetVersions(CancellationToken cancellationToken)
+            {
+                return Task.FromResult(Array.Empty<INuGetPackageVersion>() as IReadOnlyList<INuGetPackageVersion>);
+            }
+        }
+    }
+}

PettingZoo.Tapeti/UI/PackageSelection/PackageSelectionWindow.xaml

@@ -0,0 +1,126 @@
+<Window x:Class="PettingZoo.Tapeti.UI.PackageSelection.PackageSelectionWindow"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
+        xmlns:packageSelection="clr-namespace:PettingZoo.Tapeti.UI.PackageSelection"
+        xmlns:controls="clr-namespace:PettingZoo.WPF.Controls;assembly=PettingZoo.WPF"
+        mc:Ignorable="d" 
+        Title="{x:Static packageSelection:PackageSelectionStrings.WindowTitle}" 
+        Height="600" 
+        Width="800"
+        ResizeMode="CanResizeWithGrip"
+        WindowStartupLocation="CenterOwner"
+        d:DataContext="{d:DesignInstance packageSelection:DesignTimePackageSelectionViewModel, IsDesignTimeCreatable=True}">
+    <Window.Resources>
+        <ResourceDictionary>
+            <Style x:Key="PackageTitle" TargetType="{x:Type TextBlock}">
+                <Setter Property="FontWeight" Value="Bold" />
+                <Setter Property="TextTrimming" Value="CharacterEllipsis" />
+            </Style>
+
+            <Style x:Key="PackageAuthors" TargetType="{x:Type TextBlock}">
+                <Setter Property="Margin" Value="4,0,0,0" />
+                <Setter Property="TextTrimming" Value="CharacterEllipsis" />
+            </Style>
+
+            <Style x:Key="PackageDescription" TargetType="{x:Type TextBlock}">
+                <Setter Property="TextTrimming" Value="CharacterEllipsis" />
+            </Style>
+
+            <ResourceDictionary.MergedDictionaries>
+                <ResourceDictionary Source="pack://application:,,,/PettingZoo.WPF;component/Style.xaml"/>
+            </ResourceDictionary.MergedDictionaries>
+        </ResourceDictionary>
+    </Window.Resources>
+    <controls:GridLayout Style="{StaticResource Form}" Margin="8">
+        <Grid.ColumnDefinitions>
+            <ColumnDefinition Width="20" />
+            <ColumnDefinition Width="*" />
+            <ColumnDefinition Width="Auto" />
+        </Grid.ColumnDefinitions>
+        <Grid.RowDefinitions>
+            <RowDefinition Height="Auto" />
+            <RowDefinition Height="Auto" />
+            <RowDefinition Height="8" />
+            <RowDefinition Height="Auto" />
+            <RowDefinition Height="Auto"/>
+            <RowDefinition Height="Auto" />
+            <RowDefinition Height="Auto"/>
+            <RowDefinition Height="*" />
+            <RowDefinition Height="Auto"/>
+            <RowDefinition Height="Auto"/>
+            <RowDefinition Height="Auto" />
+            <RowDefinition Height="Auto" />
+        </Grid.RowDefinitions>
+
+        <RadioButton Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="3" Content="{x:Static packageSelection:PackageSelectionStrings.RadioAssembly}" IsChecked="{Binding PackageSelectionSourceAssembly}" />
+        <TextBox Grid.Row="1" Grid.Column="1" Text="{Binding AssemblyFilename, UpdateSourceTrigger=PropertyChanged}" />
+        <Button Grid.Row="1" Grid.Column="2" Content="{x:Static packageSelection:PackageSelectionStrings.ButtonBrowse}" Command="{Binding AssemblyBrowse}" />
+
+        <RadioButton Grid.Row="3" Grid.Column="0" Grid.ColumnSpan="3" Content="{x:Static packageSelection:PackageSelectionStrings.RadioNuGet}" IsChecked="{Binding PackageSelectionSourceNuGet}" />
+
+        <ComboBox Grid.Row="4" Grid.Column="1" Grid.ColumnSpan="2" ItemsSource="{Binding NuGetSources}" SelectedValue="{Binding SelectedNuGetSource}">
+            <ComboBox.ItemTemplate>
+                <DataTemplate>
+                    <TextBlock Text="{Binding Name}" />
+                </DataTemplate>
+            </ComboBox.ItemTemplate>
+        </ComboBox>
+
+        <TextBox Grid.Row="5" Grid.Column="1" Grid.ColumnSpan="2" Text="{Binding NuGetSearchTerm, UpdateSourceTrigger=PropertyChanged}" />
+        <TextBlock Grid.Row="5" Grid.Column="1" Grid.ColumnSpan="2" Text="{x:Static packageSelection:PackageSelectionStrings.PlaceholderNuGetSearch}" Visibility="{Binding NuGetSearchTermPlaceholderVisibility}" Style="{StaticResource Placeholder}" />
+
+        <CheckBox Grid.Row="6" Grid.Column="1" Grid.ColumnSpan="2" Content="{x:Static packageSelection:PackageSelectionStrings.CheckPrerelease}" IsChecked="{Binding NuGetIncludePrerelease}" />
+
+        <ListBox Grid.Row="7" Grid.Column="1" Grid.ColumnSpan="2" ItemsSource="{Binding Packages}" SelectedValue="{Binding SelectedPackage}" ScrollViewer.HorizontalScrollBarVisibility="Disabled">
+            <ListBox.ItemContainerStyle>
+                <Style TargetType="ListBoxItem">
+                    <Setter Property="HorizontalContentAlignment" Value="Stretch"/>
+                </Style>
+            </ListBox.ItemContainerStyle>
+            <ListBox.ItemTemplate>
+                <DataTemplate>
+                    <Grid>
+                        <Grid.RowDefinitions>
+                            <RowDefinition Height="Auto" />
+                            <RowDefinition Height="Auto" />
+                        </Grid.RowDefinitions>
+
+                        <Grid.ColumnDefinitions>
+                            <ColumnDefinition Width="Auto" />
+                            <ColumnDefinition Width="Auto" />
+                            <ColumnDefinition Width="*" />
+                            <ColumnDefinition Width="Auto" />
+                        </Grid.ColumnDefinitions>
+
+                        <TextBlock Grid.Row="0" Grid.Column="0" Text="{Binding Title}" Style="{StaticResource PackageTitle}" />
+                        <TextBlock Grid.Row="0" Grid.Column="1" Text="by" Style="{StaticResource PackageAuthors}" />
+                        <TextBlock Grid.Row="0" Grid.Column="2" Text="{Binding Authors}" Style="{StaticResource PackageAuthors}" />
+                        <TextBlock Grid.Row="0" Grid.Column="3" Text="{Binding Version}" />
+
+                        <TextBlock Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="3" Text="{Binding Description}" Style="{StaticResource PackageDescription}" />
+                    </Grid>
+                </DataTemplate>
+            </ListBox.ItemTemplate>
+        </ListBox>
+        <TextBlock Grid.Row="7" Grid.Column="1" Grid.ColumnSpan="2" Text="{Binding PackagesStatus}" Visibility="{Binding PackagesStatusVisibility}"  HorizontalAlignment="Center" VerticalAlignment="Center"
+                   TextWrapping="Wrap" TextAlignment="Center" Padding="32,0,32,0"/>
+
+        <TextBlock Grid.Row="8" Grid.Column="1" Grid.ColumnSpan="2" Text="{x:Static packageSelection:PackageSelectionStrings.LabelVersion}" />
+        <ComboBox Grid.Row="9" Grid.Column="1" Grid.ColumnSpan="2" ItemsSource="{Binding Versions}" SelectedValue="{Binding SelectedVersion}">
+            <ComboBox.ItemTemplate>
+                <DataTemplate>
+                    <TextBlock Text="{Binding Version}" />
+                </DataTemplate>
+            </ComboBox.ItemTemplate>
+        </ComboBox>
+
+        <TextBlock Grid.Row="10" Grid.Column="1" Grid.ColumnSpan="2" Text="{Binding HintNuGetSources}" TextWrapping="Wrap" />
+
+        <StackPanel Grid.Row="11" Grid.Column="0" Grid.ColumnSpan="3" Orientation="Horizontal" HorizontalAlignment="Right" Style="{StaticResource FooterPanel}">
+            <Button Content="{x:Static packageSelection:PackageSelectionStrings.ButtonSelect}" Style="{StaticResource FooterButton}" Command="{Binding SelectCommand}" />
+            <Button Content="{x:Static packageSelection:PackageSelectionStrings.ButtonCancel}"  Style="{StaticResource FooterButton}" />
+        </StackPanel>
+    </controls:GridLayout>
+</Window>

PettingZoo.Tapeti/UI/PackageSelection/PackageSelectionWindow.xaml.cs

@@ -0,0 +1,14 @@
+namespace PettingZoo.Tapeti.UI.PackageSelection
+{
+    /// <summary>
+    /// Interaction logic for PackageSelectionWindow.xaml
+    /// </summary>
+    public partial class PackageSelectionWindow
+    {
+        public PackageSelectionWindow(PackageSelectionViewModel viewModel)
+        {
+            DataContext = viewModel;
+            InitializeComponent();
+        }
+    }
+}

PettingZoo.WPF/Controls/GridLayout.cs

@@ -1,7 +1,7 @@
 using System.Windows;
 using System.Windows.Controls;
 
-namespace PettingZoo.UI
+namespace PettingZoo.WPF.Controls
 {
     // Source: http://daniel-albuschat.blogspot.nl/2011/07/gridlayout-for-wpf-escape-margin-hell.html
 

PettingZoo.WPF/PettingZoo.WPF.csproj

@@ -0,0 +1,21 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net6.0-windows</TargetFramework>
+    <Nullable>enable</Nullable>
+    <UseWPF>true</UseWPF>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Reference Include="ICSharpCode.AvalonEdit">
+      <HintPath>C:\Users\PsychoMark\.nuget\packages\avalonedit\6.1.2.30\lib\net5.0-windows7.0\ICSharpCode.AvalonEdit.dll</HintPath>
+    </Reference>
+  </ItemGroup>
+
+  <ItemGroup>
+    <Page Update="Style.xaml">
+      <XamlRuntime>$(DefaultXamlRuntime)</XamlRuntime>
+    </Page>
+  </ItemGroup>
+
+</Project>

PettingZoo.WPF/Style.xaml

@@ -1,17 +1,17 @@
 <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-                    xmlns:ui="clr-namespace:PettingZoo.UI"
+                    xmlns:avalonedit="http://icsharpcode.net/sharpdevelop/avalonedit"
-                    xmlns:avalonedit="http://icsharpcode.net/sharpdevelop/avalonedit">
+                    xmlns:controls="clr-namespace:PettingZoo.WPF.Controls">
     <!-- Global styling -->
     <Style x:Key="WindowStyle" TargetType="{x:Type Window}">
         <Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}"/>
     </Style>
 
-    <Style TargetType="{x:Type Button}">
+    <Style x:Key="{x:Type Button}" TargetType="{x:Type Button}">
         <Setter Property="Padding" Value="8,4"/>
     </Style>
 
-    <Style TargetType="{x:Type TextBox}">
+    <Style x:Key="{x:Type TextBox}" TargetType="{x:Type TextBox}">
         <Setter Property="Padding" Value="3" />
     </Style>
 
@@ -40,11 +40,18 @@
     </Style>
 
 
-    <Style x:Key="Form" TargetType="{x:Type ui:GridLayout}">
+    <Style x:Key="Form" TargetType="{x:Type controls:GridLayout}">
         <Setter Property="ChildMargin" Value="4"/>
     </Style>
 
 
+    <Style x:Key="Placeholder" TargetType="{x:Type TextBlock}">
+        <Setter Property="VerticalAlignment" Value="Center" />
+        <Setter Property="Padding" Value="6,0,0,0" />
+        <Setter Property="Foreground" Value="{x:Static SystemColors.GrayTextBrush}" />
+        <Setter Property="IsHitTestVisible" Value="False" />
+    </Style>
+    
     <Style x:Key="Properties" TargetType="{x:Type DataGrid}">
         <Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.WindowBrushKey}}"/>
         <Setter Property="HorizontalGridLinesBrush" Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}"/>

PettingZoo.WPF/ViewModel/BaseViewModel.cs

@@ -3,7 +3,7 @@ using System.Collections.Generic;
 using System.ComponentModel;
 using System.Runtime.CompilerServices;
 
-namespace PettingZoo.UI
+namespace PettingZoo.WPF.ViewModel
 {
     public class BaseViewModel : INotifyPropertyChanged
     {

PettingZoo.WPF/ViewModel/DelegateCommand.cs

@@ -0,0 +1,40 @@
+using System;
+using System.Windows.Input;
+
+namespace PettingZoo.WPF.ViewModel
+{
+    public class DelegateCommand : ICommand
+    {
+        private readonly Func<bool>? canExecute;
+        private readonly Action execute;
+ 
+        public event EventHandler? CanExecuteChanged;
+ 
+
+        public DelegateCommand(Action execute) : this(execute, null) { }
+ 
+        public DelegateCommand(Action execute, Func<bool>? canExecute)
+        {
+            this.execute = execute;
+            this.canExecute = canExecute;
+        }
+ 
+
+        public bool CanExecute(object? parameter)
+        {
+            return canExecute == null || canExecute();
+        }
+ 
+
+        public void Execute(object? parameter)
+        {
+            execute();
+        }
+ 
+
+        public void RaiseCanExecuteChanged()
+        {
+            CanExecuteChanged?.Invoke(this, EventArgs.Empty);
+        }
+    }
+}

PettingZoo.WPF/ViewModel/ObservableCollectionEx.cs

@@ -0,0 +1,79 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Collections.Specialized;
+
+// ReSharper disable UnusedMember.Global - public API
+
+namespace PettingZoo.WPF.ViewModel
+{
+    public class ObservableCollectionEx<T> : ObservableCollection<T>
+    {
+        private int updateLockCount;
+        private bool updatedInLock;
+
+
+        public void AddRange(IEnumerable<T> items)
+        {
+            BeginUpdate();
+            try
+            {
+                foreach (var item in items)
+                    Add(item);
+            }
+            finally
+            {
+                EndUpdate();
+            }
+        }
+
+
+        public void ReplaceAll(IEnumerable<T> newItems)
+        {
+            BeginUpdate();
+            try
+            {
+                Clear();
+                foreach (var item in newItems)
+                    Add(item);
+            }
+            finally
+            {
+                EndUpdate();
+            }
+        }
+
+
+        /// <summary>
+        /// Disables the OnCollectionChanged notification. Should always be matched with an EndUpdate to resume notifications.
+        /// </summary>
+        public void BeginUpdate()
+        {
+            updateLockCount++;
+        }
+
+
+        public void EndUpdate()
+        {
+            if (updateLockCount == 0)
+                throw new InvalidOperationException("EndUpdate does not have a matching BeginUpdate");
+
+            updateLockCount--;
+            if (updateLockCount == 0 && updatedInLock)
+                OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
+        }
+
+
+
+        protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
+        {
+            if (updateLockCount > 0)
+            {
+                updatedInLock = true;
+                return;
+            }
+
+            base.OnCollectionChanged(e);
+        }
+    }
+}

PettingZoo.sln

@@ -16,7 +16,9 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "PettingZoo.RabbitMQ", "Pett
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "PettingZoo.Tapeti", "PettingZoo.Tapeti\PettingZoo.Tapeti.csproj", "{1763AB04-59D9-4663-B207-D6302FFAACD5}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "PettingZoo.Settings.LiteDB", "PettingZoo.Settings.LiteDB\PettingZoo.Settings.LiteDB.csproj", "{7157B09C-FDD9-4928-B14D-C25B784CA865}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "PettingZoo.Settings.LiteDB", "PettingZoo.Settings.LiteDB\PettingZoo.Settings.LiteDB.csproj", "{7157B09C-FDD9-4928-B14D-C25B784CA865}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "PettingZoo.WPF", "PettingZoo.WPF\PettingZoo.WPF.csproj", "{E6617B69-2AC4-4056-B801-DD32E2374B71}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -44,6 +46,10 @@ Global
 		{7157B09C-FDD9-4928-B14D-C25B784CA865}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{7157B09C-FDD9-4928-B14D-C25B784CA865}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{7157B09C-FDD9-4928-B14D-C25B784CA865}.Release|Any CPU.Build.0 = Release|Any CPU
+		{E6617B69-2AC4-4056-B801-DD32E2374B71}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{E6617B69-2AC4-4056-B801-DD32E2374B71}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{E6617B69-2AC4-4056-B801-DD32E2374B71}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{E6617B69-2AC4-4056-B801-DD32E2374B71}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

PettingZoo.sln.DotSettings

@@ -1,5 +1,6 @@
 <wpf:ResourceDictionary xml:space="preserve" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:ss="urn:shemas-jetbrains-com:settings-storage-xaml" xmlns:wpf="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
 	<s:Boolean x:Key="/Default/CodeInspection/CodeAnnotations/NamespacesWithAnnotations/=PettingZoo_002EAnnotations/@EntryIndexedValue">True</s:Boolean>
+	<s:String x:Key="/Default/CodeStyle/CodeFormatting/CSharpCodeStyle/NAMESPACE_BODY/@EntryValue">BlockScoped</s:String>
 	<s:String x:Key="/Default/CodeStyle/Naming/CSharpNaming/Abbreviations/=DB/@EntryIndexedValue">DB</s:String>
 	<s:String x:Key="/Default/CodeStyle/Naming/CSharpNaming/Abbreviations/=DBUI/@EntryIndexedValue">DBUI</s:String>
 	<s:String x:Key="/Default/CodeStyle/Naming/CSharpNaming/Abbreviations/=UI/@EntryIndexedValue">UI</s:String>

PettingZoo/App.xaml

@@ -6,7 +6,7 @@
   <Application.Resources>
       <ResourceDictionary>
             <ResourceDictionary.MergedDictionaries>
-                <ResourceDictionary Source="Style.xaml"/>
+                <ResourceDictionary Source="pack://application:,,,/PettingZoo.WPF;component/Style.xaml"/>
             </ResourceDictionary.MergedDictionaries>
         </ResourceDictionary>
   </Application.Resources>

PettingZoo/App.xaml.cs

@@ -6,6 +6,7 @@ using System.Windows;
 using System.Windows.Threading;
 using PettingZoo.Core.Settings;
 using PettingZoo.UI.Main;
+using Serilog;
 using SimpleInjector;
 using Point = System.Windows.Point;
 
@@ -14,6 +15,7 @@ namespace PettingZoo
     public partial class App
     {
         private readonly Container container;
+        private readonly ILogger logger;
 
 
         public App()
@@ -22,9 +24,10 @@ namespace PettingZoo
         }
 
 
-        public App(Container container)
+        public App(Container container, ILogger logger)
         {
             this.container = container;
+            this.logger = logger;
         }
 
 
@@ -80,6 +83,7 @@ namespace PettingZoo
 
         private void App_OnDispatcherUnhandledException(object sender, DispatcherUnhandledExceptionEventArgs e)
         {
+            logger.Error(e.Exception, "Unhandled exception");
             _ = MessageBox.Show($"Unhandled exception: {e.Exception.Message}", "Petting Zoo - Exception", MessageBoxButton.OK, MessageBoxImage.Error);
         }
     }

PettingZoo/Images/Example.svg

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="iso-8859-1"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<svg version="1.1" id="Capa_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
+	 viewBox="0 0 58 58" style="enable-background:new 0 0 58 58;" xml:space="preserve">
+<g>
+	<g>
+		<polygon style="fill:#EFEBDE;" points="46.5,14 32.5,0 1.5,0 1.5,58 46.5,58 		"/>
+		<g>
+			<path style="fill:#D5D0BB;" d="M11.5,23h25c0.552,0,1-0.447,1-1s-0.448-1-1-1h-25c-0.552,0-1,0.447-1,1S10.948,23,11.5,23z"/>
+			<path style="fill:#D5D0BB;" d="M11.5,15h10c0.552,0,1-0.447,1-1s-0.448-1-1-1h-10c-0.552,0-1,0.447-1,1S10.948,15,11.5,15z"/>
+			<path style="fill:#D5D0BB;" d="M36.5,29h-25c-0.552,0-1,0.447-1,1s0.448,1,1,1h25c0.552,0,1-0.447,1-1S37.052,29,36.5,29z"/>
+			<path style="fill:#D5D0BB;" d="M36.5,37h-25c-0.552,0-1,0.447-1,1s0.448,1,1,1h25c0.552,0,1-0.447,1-1S37.052,37,36.5,37z"/>
+			<path style="fill:#D5D0BB;" d="M36.5,45h-25c-0.552,0-1,0.447-1,1s0.448,1,1,1h25c0.552,0,1-0.447,1-1S37.052,45,36.5,45z"/>
+		</g>
+		<polygon style="fill:#D5D0BB;" points="32.5,0 32.5,14 46.5,14 		"/>
+	</g>
+</g>
+</svg>

PettingZoo/Images/Folder.svg

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="iso-8859-1"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<svg version="1.1" id="Capa_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
+	 viewBox="0 0 59.39 59.39" style="enable-background:new 0 0 59.39 59.39;" xml:space="preserve">
+<g>
+	<polygon style="fill:#556080;" points="25,10.695 20,3.695 0,3.695 0,10.695 0,54.695 58,54.695 58,17.695 30,17.695 	"/>
+	<polygon style="fill:#3D4451;" points="30,17.695 58,17.695 58,10.695 25,10.695 	"/>
+</g>
+</svg>

PettingZoo/PettingZoo.csproj

@@ -22,6 +22,8 @@
     <None Remove="Images\Busy.svg" />
     <None Remove="Images\Dock.svg" />
     <None Remove="Images\Error.svg" />
+    <None Remove="Images\Example.svg" />
+    <None Remove="Images\Folder.svg" />
     <None Remove="Images\Ok.svg" />
     <None Remove="Images\PublishSend.svg" />
     <None Remove="Images\Undock.svg" />
@@ -33,6 +35,8 @@
     <Resource Include="Images\Disconnect.svg" />
     <Resource Include="Images\Dock.svg" />
     <Resource Include="Images\Error.svg" />
+    <Resource Include="Images\Example.svg" />
+    <Resource Include="Images\Folder.svg" />
     <Resource Include="Images\Ok.svg" />
     <Resource Include="Images\Publish.svg" />
     <Resource Include="Images\PublishSend.svg" />
@@ -40,8 +44,10 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="AvalonEdit" Version="6.1.2.30" />
+    <PackageReference Include="AvalonEdit" Version="6.1.3.50" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
+    <PackageReference Include="Serilog" Version="2.10.0" />
+    <PackageReference Include="Serilog.Sinks.File" Version="5.0.0" />
     <PackageReference Include="SharpVectors" Version="1.7.7" />
     <PackageReference Include="SimpleInjector" Version="5.3.2" />
     <PackageReference Include="System.Reactive" Version="5.0.0" />
@@ -51,6 +57,8 @@
     <ProjectReference Include="..\PettingZoo.Core\PettingZoo.Core.csproj" />
     <ProjectReference Include="..\PettingZoo.RabbitMQ\PettingZoo.RabbitMQ.csproj" />
     <ProjectReference Include="..\PettingZoo.Settings.LiteDB\PettingZoo.Settings.LiteDB.csproj" />
+    <ProjectReference Include="..\PettingZoo.Tapeti\PettingZoo.Tapeti.csproj" />
+    <ProjectReference Include="..\PettingZoo.WPF\PettingZoo.WPF.csproj" />
   </ItemGroup>
 
   <ItemGroup>
@@ -69,11 +77,6 @@
       <DesignTime>True</DesignTime>
       <AutoGen>True</AutoGen>
     </Compile>
-    <Compile Update="UI\Example\ExamplePickerDialogStrings.Designer.cs">
-      <DesignTime>True</DesignTime>
-      <AutoGen>True</AutoGen>
-      <DependentUpon>ExamplePickerDialogStrings.resx</DependentUpon>
-    </Compile>
     <Compile Update="UI\Main\MainWindowStrings.Designer.cs">
       <DependentUpon>MainWindowStrings.resx</DependentUpon>
       <DesignTime>True</DesignTime>
@@ -128,10 +131,6 @@
       <LastGenOutput>ConnectionWindowStrings.Designer.cs</LastGenOutput>
       <Generator>PublicResXFileCodeGenerator</Generator>
     </EmbeddedResource>
-    <EmbeddedResource Update="UI\Example\ExamplePickerDialogStrings.resx">
-      <Generator>PublicResXFileCodeGenerator</Generator>
-      <LastGenOutput>ExamplePickerDialogStrings.Designer.cs</LastGenOutput>
-    </EmbeddedResource>
     <EmbeddedResource Update="UI\Main\MainWindowStrings.resx">
       <LastGenOutput>MainWindowStrings.Designer.cs</LastGenOutput>
       <Generator>PublicResXFileCodeGenerator</Generator>

PettingZoo/Program.cs

@@ -1,15 +1,18 @@
 using System;
 using System.Globalization;
-using System.Threading.Tasks;
+using System.IO;
 using System.Windows;
 using System.Windows.Markup;
 using PettingZoo.Core.Connection;
+using PettingZoo.Core.Generator;
 using PettingZoo.Core.Settings;
 using PettingZoo.RabbitMQ;
 using PettingZoo.Settings.LiteDB;
+using PettingZoo.Tapeti;
 using PettingZoo.UI.Connection;
 using PettingZoo.UI.Main;
 using PettingZoo.UI.Subscribe;
+using Serilog;
 using SimpleInjector;
 
 namespace PettingZoo
@@ -23,23 +26,59 @@ namespace PettingZoo
             FrameworkElement.LanguageProperty.OverrideMetadata(typeof(FrameworkElement), new FrameworkPropertyMetadata(
                 XmlLanguage.GetLanguage(CultureInfo.CurrentCulture.IetfLanguageTag)));
 
-            var container = Bootstrap();
+            try
-            RunApplication(container);
+            {
+                var logger = CreateLogger();
+                try
+                {
+                    logger.Verbose("Bootstrapping...");
+                    var container = Bootstrap(logger);
+
+                    logger.Verbose("Running application...");
+                    RunApplication(container, logger);
+                }
+                catch (Exception e)
+                {
+                    logger.Error(e, "Unhandled exception");
+                    throw;
+                }
+                finally
+                {
+                    logger.Verbose("Shutting down");
+                }
+            }
+            catch (Exception e)
+            {
+                _ = MessageBox.Show($"Unhandled exception: {e.Message}", "Petting Zoo - Exception", MessageBoxButton.OK, MessageBoxImage.Error);
+            }
         }
 
 
-        private static Container Bootstrap()
+        private static ILogger CreateLogger()
+        {
+            var logPath = Path.Combine(PettingZooPaths.AppDataRoot, @"logs", "PettingZoo.log");
+
+            return new LoggerConfiguration()
+                .MinimumLevel.Verbose()
+                .WriteTo.File(logPath, rollingInterval: RollingInterval.Day)
+                .CreateLogger();
+        }
+
+
+        private static Container Bootstrap(ILogger logger)
         {
             var container = new Container();
             
             // See comments in RunApplication
             container.Options.EnableAutoVerification = false;
 
+            container.RegisterInstance(logger);
             container.Register<IConnectionFactory, RabbitMQClientConnectionFactory>();
             container.Register<IConnectionDialog, WindowConnectionDialog>();
             container.Register<ISubscribeDialog, WindowSubscribeDialog>();
             container.Register<IConnectionSettingsRepository, LiteDBConnectionSettingsRepository>();
             container.Register<IUISettingsRepository, LiteDBUISettingsRepository>();
+            container.Register<IExampleGenerator, TapetiClassLibraryExampleGenerator>();
 
             container.Register<MainWindow>();
             
@@ -47,32 +86,25 @@ namespace PettingZoo
         }
 
 
-        private static void RunApplication(Container container)
+        private static void RunApplication(Container container, ILogger logger)
         {
-            try
+            var app = new App(container, logger);
-            {
+            app.InitializeComponent();
-                var app = new App(container);
-                app.InitializeComponent();
 
-                #if DEBUG
+            #if DEBUG
-                // Verify container after initialization to prevent issues loading the resource dictionaries
+            // Verify container after initialization to prevent issues loading the resource dictionaries
-                container.Verify();
+            container.Verify();
 
-                // This causes the MainWindow and Windows properties to be populated however, which we don't want
+            // This causes the MainWindow and Windows properties to be populated however, which we don't want
-                // because then the app does not close properly when using OnMainWindowClose, so clean up the mess
+            // because then the app does not close properly when using OnMainWindowClose, so clean up the mess
-                app.MainWindow = null;
+            app.MainWindow = null;
-                foreach (var window in app.Windows)
+            foreach (var window in app.Windows)
-                    ((Window)window).Close();
+                ((Window)window).Close();
             
-                // All this is the reason we only perform verification in debug builds
+            // All this is the reason we only perform verification in debug builds
-                #endif
+            #endif
             
-                app.Run();
+            app.Run();
-            }
-            catch (Exception e)
-            {
-                MessageBox.Show($"Fatal exception: {e.Message}", @"PettingZoo", MessageBoxButton.OK, MessageBoxImage.Error);
-            }
         }
     }
 }

PettingZoo/UI/Connection/ConnectionDisplayNameViewModel.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Windows.Input;
+using PettingZoo.WPF.ViewModel;
 
 namespace PettingZoo.UI.Connection
 {

PettingZoo/UI/Connection/ConnectionViewModel.cs

@@ -4,6 +4,7 @@ using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Input;
 using PettingZoo.Core.Settings;
+using PettingZoo.WPF.ViewModel;
 
 namespace PettingZoo.UI.Connection
 {
@@ -207,10 +208,7 @@ namespace PettingZoo.UI.Connection
                    Port > 0 &&
                    !string.IsNullOrWhiteSpace(Username) &&
                    (!requirePassword || !string.IsNullOrWhiteSpace(Password)) &&
-                   (!Subscribe || (
+                   (!Subscribe || !string.IsNullOrWhiteSpace(Exchange) && !string.IsNullOrWhiteSpace(RoutingKey));
-                       !string.IsNullOrWhiteSpace(Exchange) &&
-                       !string.IsNullOrWhiteSpace(RoutingKey)
-                       ));
         }
 
 

PettingZoo/UI/Connection/ConnectionWindow.xaml

@@ -5,6 +5,7 @@
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
         xmlns:ui="clr-namespace:PettingZoo.UI"
         xmlns:connection="clr-namespace:PettingZoo.UI.Connection"
+        xmlns:controls="clr-namespace:PettingZoo.WPF.Controls;assembly=PettingZoo.WPF"
         mc:Ignorable="d"
         d:DataContext="{d:DesignInstance connection:DesignTimeConnectionViewModel, IsDesignTimeCreatable = True}"
         Width="700" 
@@ -58,7 +59,7 @@
             </ListBox.ItemTemplate>
         </ListBox>
 
-        <ui:GridLayout Style="{StaticResource Form}" Grid.Row="0" Grid.Column="1" Grid.ColumnSpan="2">
+        <controls:GridLayout Style="{StaticResource Form}" Grid.Row="0" Grid.Column="1" Grid.ColumnSpan="2">
             <Grid.ColumnDefinitions>
                 <ColumnDefinition Width="Auto"/>
                 <ColumnDefinition Width="*"/>
@@ -98,7 +99,7 @@
 
             <Label Grid.Column="0" Grid.Row="9" Content="{x:Static connection:ConnectionWindowStrings.LabelRoutingKey}"/>
             <TextBox Grid.Column="1" Grid.Row="9" Text="{Binding RoutingKey, UpdateSourceTrigger=PropertyChanged}" GotFocus="CaretToEnd"/>
-        </ui:GridLayout>
+        </controls:GridLayout>
     </Grid>
 </Window>
 

PettingZoo/UI/Connection/IConnectionDialog.cs

@@ -1,5 +1,4 @@
-using System;
+using System.Threading.Tasks;
-using System.Threading.Tasks;
 using PettingZoo.Core.Settings;
 
 namespace PettingZoo.UI.Connection

PettingZoo/UI/DelegateCommand.cs

@@ -1,79 +0,0 @@
-using System;
-using System.Windows.Input;
-
-namespace PettingZoo.UI
-{
-    public class DelegateCommand<T> : ICommand where T : class?
-    {
-        private readonly Func<T?, bool>? canExecute;
-        private readonly Action<T?> execute;
-
-        public event EventHandler? CanExecuteChanged;
-
-
-        public DelegateCommand(Action<T?> execute) : this(execute, null)
-        {
-        }
-
-        public DelegateCommand(Action<T?> execute, Func<T?, bool>? canExecute)
-        {
-            this.execute = execute;
-            this.canExecute = canExecute;
-        }
-
-
-        public bool CanExecute(object? parameter)
-        {
-            return canExecute == null || canExecute((T?)parameter);
-        }
-
-
-        public void Execute(object? parameter)
-        {
-            execute((T?)parameter);
-        }
-
-
-        public void RaiseCanExecuteChanged()
-        {
-            CanExecuteChanged?.Invoke(this, EventArgs.Empty);
-        }
-    }
-
-
-
-    public class DelegateCommand : ICommand
-    {
-        private readonly Func<bool>? canExecute;
-        private readonly Action execute;
- 
-        public event EventHandler? CanExecuteChanged;
- 
-
-        public DelegateCommand(Action execute) : this(execute, null) { }
- 
-        public DelegateCommand(Action execute, Func<bool>? canExecute)
-        {
-            this.execute = execute;
-            this.canExecute = canExecute;
-        }
- 
-
-        public bool CanExecute(object? parameter)
-        {
-            return canExecute == null || canExecute();
-        }
- 
-
-        public void Execute(object? parameter)
-        {
-            execute();
-        }
- 
-
-        public void RaiseCanExecuteChanged()
-        {
-            CanExecuteChanged?.Invoke(this, EventArgs.Empty);
-        }
-    }
-}

PettingZoo/UI/EnumBooleanConverter.cs

@@ -13,7 +13,7 @@ namespace PettingZoo.UI
 
         public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
         {
-            return ((bool)value) ? parameter : Binding.DoNothing;
+            return (bool)value ? parameter : Binding.DoNothing;
         }
     }
 }

PettingZoo/UI/Example/ExamplePickerDialog.xaml

@@ -1,12 +0,0 @@
-<Window x:Class="PettingZoo.UI.Example.ExamplePickerDialog"
-        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
-        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
-        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-        xmlns:example="clr-namespace:PettingZoo.UI.Example"
-        mc:Ignorable="d"
-        Title="{x:Static example:ExamplePickerDialogStrings.WindowTitle}" Height="800" Width="600">
-    <Grid>
-        
-    </Grid>
-</Window>

PettingZoo/UI/Example/ExamplePickerDialog.xaml.cs

@@ -1,15 +0,0 @@
-using System.Windows;
-
-namespace PettingZoo.UI.Example
-{
-    /// <summary>
-    /// Interaction logic for ExamplePickerDialog.xaml
-    /// </summary>
-    public partial class ExamplePickerDialog : Window
-    {
-        public ExamplePickerDialog()
-        {
-            InitializeComponent();
-        }
-    }
-}

PettingZoo/UI/Example/ExamplePickerDialogViewModel.cs

@@ -1,6 +0,0 @@
-namespace PettingZoo.UI.Example
-{
-    public class ExamplePickerDialogViewModel
-    {
-    }
-}

PettingZoo/UI/ListBoxAutoScroll.cs

@@ -6,6 +6,8 @@ using System.Windows.Controls;
 using System.Windows.Data;
 using System.Windows.Media;
 
+// ReSharper disable UnusedMember.Global - public API
+
 namespace PettingZoo.UI
 {
     // Source: https://social.msdn.microsoft.com/Forums/vstudio/en-US/0f524459-b14e-4f9a-8264-267953418a2d/trivial-listboxlistview-autoscroll?forum=wpf

PettingZoo/UI/Main/MainWindow.xaml.cs

@@ -5,6 +5,7 @@ using System.Windows.Controls;
 using System.Windows.Input;
 using System.Windows.Media;
 using PettingZoo.Core.Connection;
+using PettingZoo.Core.Generator;
 using PettingZoo.UI.Connection;
 using PettingZoo.UI.Subscribe;
 using PettingZoo.UI.Tab;
@@ -19,11 +20,15 @@ namespace PettingZoo.UI.Main
         public bool WasMaximized;
         
 
-        public MainWindow(IConnectionFactory connectionFactory, IConnectionDialog connectionDialog, ISubscribeDialog subscribeDialog)
+        public MainWindow(IConnectionFactory connectionFactory, IConnectionDialog connectionDialog, ISubscribeDialog subscribeDialog, IExampleGenerator exampleGenerator)
         {
             WindowStartupLocation = WindowStartupLocation.CenterScreen;
 
-            viewModel = new MainWindowViewModel(connectionFactory, connectionDialog, subscribeDialog, this);
+            viewModel = new MainWindowViewModel(connectionFactory, connectionDialog, subscribeDialog, this, exampleGenerator)
+            {
+                TabHostWindow = this
+            };
+
             DataContext = viewModel;
             InitializeComponent();
 

PettingZoo/UI/Main/MainWindowViewModel.cs

@@ -6,10 +6,12 @@ using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Input;
 using PettingZoo.Core.Connection;
+using PettingZoo.Core.Generator;
 using PettingZoo.UI.Connection;
 using PettingZoo.UI.Subscribe;
 using PettingZoo.UI.Tab;
 using PettingZoo.UI.Tab.Undocked;
+using PettingZoo.WPF.ViewModel;
 
 namespace PettingZoo.UI.Main
 {
@@ -44,6 +46,8 @@ namespace PettingZoo.UI.Main
 
         private ConnectionStatusType connectionStatusType;
 
+        public Window? TabHostWindow { get; set; }
+
 
         public string ConnectionStatus
         {
@@ -75,8 +79,8 @@ namespace PettingZoo.UI.Main
                 if (!SetField(ref activeTab, value, otherPropertiesChanged: new[] { nameof(ToolbarCommands), nameof(ToolbarCommandsSeparatorVisibility) }))
                     return;
 
-                currentTab?.Deactivate();
+                (currentTab as ITabActivate)?.Deactivate();
-                activeTab?.Activate();
+                (activeTab as ITabActivate)?.Activate();
             }
         }
 
@@ -99,7 +103,7 @@ namespace PettingZoo.UI.Main
 
 
         public MainWindowViewModel(IConnectionFactory connectionFactory, IConnectionDialog connectionDialog, 
-            ISubscribeDialog subscribeDialog, ITabContainer tabContainer)
+            ISubscribeDialog subscribeDialog, ITabContainer tabContainer, IExampleGenerator exampleGenerator)
         {
             this.connectionFactory = connectionFactory;
             this.connectionDialog = connectionDialog;
@@ -117,7 +121,7 @@ namespace PettingZoo.UI.Main
             closeTabCommand = new DelegateCommand(CloseTabExecute, HasActiveTabCanExecute);
             undockTabCommand = new DelegateCommand(UndockTabExecute, HasActiveTabCanExecute);
 
-            tabFactory = new ViewTabFactory(this);
+            tabFactory = new ViewTabFactory(this, exampleGenerator);
         }
 
 
@@ -226,6 +230,7 @@ namespace PettingZoo.UI.Main
             undockedTabs.Add(tab, tabHostWindow);
 
             tabHostWindow.Show();
+            (tab as ITabHostWindowNotify)?.HostWindowChanged(tabHostWindow);
         }
 
 
@@ -264,6 +269,8 @@ namespace PettingZoo.UI.Main
             Tabs.Add(tab);
             ActiveTab = tab;
 
+            (tab as ITabHostWindowNotify)?.HostWindowChanged(TabHostWindow);
+
             closeTabCommand.RaiseCanExecuteChanged();
             undockTabCommand.RaiseCanExecuteChanged();
             RaisePropertyChanged(nameof(NoTabsVisibility));
@@ -276,6 +283,9 @@ namespace PettingZoo.UI.Main
                 tabHostWindow.Close();
 
             AddTab(tab);
+            ActiveTab = tab;
+
+            (tab as ITabHostWindowNotify)?.HostWindowChanged(TabHostWindow);
         }
 
         public void UndockedTabClosed(ITab tab)
@@ -320,7 +330,7 @@ namespace PettingZoo.UI.Main
     
     public class DesignTimeMainWindowViewModel : MainWindowViewModel
     {
-        public DesignTimeMainWindowViewModel() : base(null!, null!, null!, null!)
+        public DesignTimeMainWindowViewModel() : base(null!, null!, null!, null!, null!)
         {
         }
     }

PettingZoo/UI/PasswordBoxAssistant.cs

@@ -1,6 +1,8 @@
 using System.Windows;
 using System.Windows.Controls;
 
+// ReSharper disable UnusedMember.Global - public API
+
 namespace PettingZoo.UI
 {
     // Source: http://blog.functionalfun.net/2008/06/wpf-passwordbox-and-data-binding.html
@@ -20,14 +22,10 @@ namespace PettingZoo.UI
 
         private static void OnBoundPasswordChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
         {
-            var box = d as PasswordBox;
-
             // only handle this event when the property is attached to a PasswordBox
             // and when the BindPassword attached property has been set to true
-            if (box == null || !GetBindPassword(d))
+            if (d is not PasswordBox box || !GetBindPassword(d))
-            {
                 return;
-            }
 
             // avoid recursive updating by ignoring the box's changed event
             box.PasswordChanged -= HandlePasswordChanged;
@@ -61,8 +59,7 @@ namespace PettingZoo.UI
 
         private static void HandlePasswordChanged(object sender, RoutedEventArgs e)
         {
-            var box = sender as PasswordBox;
+            if (sender is not PasswordBox box)
-            if (box == null)
                 return;
 
             // set a flag to indicate that we're updating the password

PettingZoo/UI/Subscribe/ISubscribeDialog.cs

@@ -1,6 +1,4 @@
-using System;
+namespace PettingZoo.UI.Subscribe
-
-namespace PettingZoo.UI.Subscribe
 {
     public interface ISubscribeDialog
     {

PettingZoo/UI/Subscribe/SubscribeViewModel.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Windows.Input;
+using PettingZoo.WPF.ViewModel;
 
 // TODO validate input
 
@@ -40,7 +41,7 @@ namespace PettingZoo.UI.Subscribe
         
         public SubscribeDialogParams ToModel()
         {
-            return new(Exchange, RoutingKey);
+            return new SubscribeDialogParams(Exchange, RoutingKey);
         }
 
 

PettingZoo/UI/Subscribe/SubscribeWindow.xaml

@@ -3,11 +3,10 @@
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
-        xmlns:ui="clr-namespace:PettingZoo.UI"
-        xmlns:connection="clr-namespace:PettingZoo.UI.Connection"
         xmlns:subscribe="clr-namespace:PettingZoo.UI.Subscribe"
+        xmlns:controls="clr-namespace:PettingZoo.WPF.Controls;assembly=PettingZoo.WPF"
         mc:Ignorable="d"
-        d:DataContext="{d:DesignInstance connection:DesignTimeConnectionViewModel, IsDesignTimeCreatable = True}"
+        d:DataContext="{d:DesignInstance subscribe:DesignTimeSubscribeViewModel, IsDesignTimeCreatable=True}"
         Width="500" 
         SizeToContent="Height"
         ResizeMode="NoResize"
@@ -21,7 +20,7 @@
             <Button IsCancel="True" Content="{x:Static subscribe:SubscribeWindowStrings.ButtonCancel}" Style="{StaticResource FooterButton}"/>
         </UniformGrid>
         
-        <ui:GridLayout Style="{StaticResource Form}">
+        <controls:GridLayout Style="{StaticResource Form}">
             <Grid.ColumnDefinitions>
                 <ColumnDefinition Width="Auto"/>
                 <ColumnDefinition Width="*"/>
@@ -35,7 +34,7 @@
 
             <Label Grid.Column="0" Grid.Row="1" Content="{x:Static subscribe:SubscribeWindowStrings.LabelRoutingKey}"/>
             <TextBox Grid.Column="1" Grid.Row="1" Text="{Binding RoutingKey}"/>
-        </ui:GridLayout>
+        </controls:GridLayout>
     </DockPanel>
 </Window>
 

PettingZoo/UI/Tab/ITab.cs

@@ -1,12 +1,20 @@
 using System.Collections.Generic;
 using System.ComponentModel;
+using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Input;
 using System.Windows.Media;
 
 namespace PettingZoo.UI.Tab
 {
-    public interface ITabToolbarCommands : INotifyPropertyChanged
+    public interface ITab : INotifyPropertyChanged
+    {
+        string Title { get; }
+        ContentControl Content { get; }
+    }
+
+
+    public interface ITabToolbarCommands
     {
         IEnumerable<TabToolbarCommand> ToolbarCommands { get; }
     }
@@ -19,10 +27,9 @@ namespace PettingZoo.UI.Tab
     }
 
 
-    public interface ITab : ITabToolbarCommands, ITabActivate
+    public interface ITabHostWindowNotify
     {
-        string Title { get; }
+        void HostWindowChanged(Window? hostWindow);
-        ContentControl Content { get; }
     }
 
 

PettingZoo/UI/Tab/Publisher/PayloadEditorControl.xaml.cs

@@ -148,26 +148,47 @@ namespace PettingZoo.UI.Tab.Publisher
             // https://stackoverflow.com/questions/18964176/two-way-binding-to-avalonedit-document-text-using-mvvm
             Editor.Document.Text = Payload;
 
+
+            var editorTriggered = false;
+
             Editor.TextChanged += (_, _) =>
             {
-                Payload = Editor.Document.Text;
+                editorTriggered = true;
+                try
+                {
+                    Payload = Editor.Document.Text;
+                }
+                finally
+                {
+                    editorTriggered = false;
+                }
             };
 
 
             viewModel.PropertyChanged += (_, args) =>
             {
-                if (args.PropertyName != nameof(viewModel.ValidationInfo))
+                if (args.PropertyName != nameof(viewModel.ValidationInfo) && 
+                    (args.PropertyName != nameof(viewModel.Payload) || editorTriggered))
                     return;
 
                 Dispatcher.Invoke(() =>
                 {
-                    if (errorHighlightingTransformer.ErrorPosition == viewModel.ValidationInfo.ErrorPosition)
+                    switch (args.PropertyName)
-                        return;
+                    {
+                        case nameof(viewModel.ValidationInfo):
+                            if (errorHighlightingTransformer.ErrorPosition == viewModel.ValidationInfo.ErrorPosition)
+                                return;
 
-                    errorHighlightingTransformer.ErrorPosition = viewModel.ValidationInfo.ErrorPosition;
+                            errorHighlightingTransformer.ErrorPosition = viewModel.ValidationInfo.ErrorPosition;
 
-                    // TODO this can probably be optimized to only redraw the affected line
+                            // TODO this can probably be optimized to only redraw the affected line
-                    Editor.TextArea.TextView.Redraw();
+                            Editor.TextArea.TextView.Redraw();
+                            break;
+
+                        case nameof(viewModel.Payload):
+                            Editor.Document.Text = viewModel.Payload;
+                            break;
+                    }
                 });
             };
 

PettingZoo/UI/Tab/Publisher/PayloadEditorViewModel.cs

@@ -5,6 +5,7 @@ using System.Windows;
 using ICSharpCode.AvalonEdit.Highlighting;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
+using PettingZoo.WPF.ViewModel;
 
 namespace PettingZoo.UI.Tab.Publisher
 {
@@ -13,7 +14,7 @@ namespace PettingZoo.UI.Tab.Publisher
         Json,
         Plain,
         Other
-    };
+    }
 
 
     public enum ValidationStatus

PettingZoo/UI/Tab/Publisher/PublisherView.xaml

@@ -4,14 +4,14 @@
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:res="clr-namespace:PettingZoo.UI.Tab.Publisher"
-             xmlns:ui="clr-namespace:PettingZoo.UI"
+             xmlns:controls="clr-namespace:PettingZoo.WPF.Controls;assembly=PettingZoo.WPF"
              mc:Ignorable="d" 
              d:DesignHeight="450" 
              d:DesignWidth="800"
              d:DataContext="{d:DesignInstance res:DesignTimePublisherViewModel, IsDesignTimeCreatable=True}"
              Background="White">
     <ScrollViewer VerticalScrollBarVisibility="Auto">
-        <ui:GridLayout Style="{StaticResource Form}" Margin="4" Grid.IsSharedSizeScope="True">
+        <controls:GridLayout Style="{StaticResource Form}" Margin="4" Grid.IsSharedSizeScope="True">
             <Grid.RowDefinitions>
                 <RowDefinition Height="Auto"/>
                 <RowDefinition Height="Auto"/>
@@ -61,6 +61,6 @@
             <ContentControl Grid.Row="9" Grid.Column="0" Grid.ColumnSpan="2" Margin="0 8 0 0" Content="{Binding MessageTypeControl}" />
 
             <Button Grid.Row="10" Grid.Column="1" Command="{Binding PublishCommand}" Content="{x:Static res:PublisherViewStrings.CommandPublish}" HorizontalAlignment="Left" />
-        </ui:GridLayout>
+        </controls:GridLayout>
     </ScrollViewer>
 </UserControl>

PettingZoo/UI/Tab/Publisher/PublisherViewModel.cs

@@ -4,6 +4,8 @@ using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Input;
 using PettingZoo.Core.Connection;
+using PettingZoo.Core.Generator;
+using PettingZoo.WPF.ViewModel;
 
 namespace PettingZoo.UI.Tab.Publisher
 {
@@ -14,9 +16,10 @@ namespace PettingZoo.UI.Tab.Publisher
     }
     
 
-    public class PublisherViewModel : BaseViewModel, ITabToolbarCommands, IPublishDestination
+    public class PublisherViewModel : BaseViewModel, ITabToolbarCommands, ITabHostWindowNotify, IPublishDestination
     {
         private readonly IConnection connection;
+        private readonly IExampleGenerator exampleGenerator;
         private readonly ITabFactory tabFactory;
         private readonly ITabHost tabHost;
 
@@ -36,6 +39,7 @@ namespace PettingZoo.UI.Tab.Publisher
 
         private readonly DelegateCommand publishCommand;
         private readonly TabToolbarCommand[] toolbarCommands;
+        private Window? tabHostWindow;
 
 
         public bool SendToExchange
@@ -150,9 +154,10 @@ namespace PettingZoo.UI.Tab.Publisher
         string IPublishDestination.RoutingKey => SendToExchange ? RoutingKey : Queue;
 
 
-        public PublisherViewModel(ITabHost tabHost, ITabFactory tabFactory, IConnection connection, ReceivedMessageInfo? fromReceivedMessage = null)
+        public PublisherViewModel(ITabHost tabHost, ITabFactory tabFactory, IConnection connection, IExampleGenerator exampleGenerator, ReceivedMessageInfo? fromReceivedMessage = null)
         {
             this.connection = connection;
+            this.exampleGenerator = exampleGenerator;
             this.tabFactory = tabFactory;
             this.tabHost = tabHost;
 
@@ -187,16 +192,35 @@ namespace PettingZoo.UI.Tab.Publisher
             switch (value)
             {
                 case MessageType.Raw:
-                    var rawPublisherViewModel = new RawPublisherViewModel(connection, this);
+                    RawPublisherViewModel rawPublisherViewModel;
-                    rawPublisherView ??= new RawPublisherView(rawPublisherViewModel);
+
+                    if (rawPublisherView == null)
+                    {
+                        rawPublisherViewModel = new RawPublisherViewModel(connection, this);
+                        rawPublisherView ??= new RawPublisherView(rawPublisherViewModel);
+                    }
+                    else
+                        rawPublisherViewModel = (RawPublisherViewModel)rawPublisherView.DataContext;
+
                     MessageTypeControl = rawPublisherView;
 
                     messageTypePublishCommand = rawPublisherViewModel.PublishCommand;
                     break;
                     
                 case MessageType.Tapeti:
-                    var tapetiPublisherViewModel = new TapetiPublisherViewModel(connection, this);
+                    TapetiPublisherViewModel tapetiPublisherViewModel;
-                    tapetiPublisherView ??= new TapetiPublisherView(tapetiPublisherViewModel);
+
+                    if (tapetiPublisherView == null)
+                    {
+                        tapetiPublisherViewModel = new TapetiPublisherViewModel(connection, this, exampleGenerator);
+                        tapetiPublisherView ??= new TapetiPublisherView(tapetiPublisherViewModel);
+
+                        if (tabHostWindow != null)
+                            tapetiPublisherViewModel.HostWindowChanged(tabHostWindow);
+                    }
+                    else
+                        tapetiPublisherViewModel = (TapetiPublisherViewModel)tapetiPublisherView.DataContext;
+
                     MessageTypeControl = tapetiPublisherView;
 
                     messageTypePublishCommand = tapetiPublisherViewModel.PublishCommand;
@@ -218,7 +242,7 @@ namespace PettingZoo.UI.Tab.Publisher
 
             if (TapetiPublisherViewModel.IsTapetiMessage(fromReceivedMessage))
             {
-                var tapetiPublisherViewModel = new TapetiPublisherViewModel(connection, this, fromReceivedMessage);
+                var tapetiPublisherViewModel = new TapetiPublisherViewModel(connection, this, exampleGenerator, fromReceivedMessage);
                 tapetiPublisherView = new TapetiPublisherView(tapetiPublisherViewModel);
 
                 MessageType = MessageType.Tapeti;
@@ -245,12 +269,20 @@ namespace PettingZoo.UI.Tab.Publisher
             subscriber.Start();
             return subscriber.QueueName;
         }
+
+
+        public void HostWindowChanged(Window? hostWindow)
+        {
+            tabHostWindow = hostWindow;
+
+            (tapetiPublisherView?.DataContext as TapetiPublisherViewModel)?.HostWindowChanged(hostWindow);
+        }
     }
 
 
     public class DesignTimePublisherViewModel : PublisherViewModel
     {
-        public DesignTimePublisherViewModel() : base(null!, null!, null!)
+        public DesignTimePublisherViewModel() : base(null!, null!, null!, null!)
         {
         }
 

PettingZoo/UI/Tab/Publisher/RawPublisherView.xaml

@@ -4,18 +4,18 @@
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:publisher="clr-namespace:PettingZoo.UI.Tab.Publisher"
-             xmlns:ui="clr-namespace:PettingZoo.UI"
+             xmlns:controls="clr-namespace:PettingZoo.WPF.Controls;assembly=PettingZoo.WPF"
              mc:Ignorable="d" 
              d:DesignHeight="800" d:DesignWidth="800"
              d:DataContext="{d:DesignInstance publisher:DesignTimeRawPublisherViewModel, IsDesignTimeCreatable=True}"
              Background="White">
-    <ui:GridLayout Style="{StaticResource Form}">
+    <controls:GridLayout Style="{StaticResource Form}">
         <Grid.ColumnDefinitions>
             <ColumnDefinition Width="Auto" SharedSizeGroup="Label" />
             <ColumnDefinition Width="*" />
         </Grid.ColumnDefinitions>
 
-        <ui:GridLayout.RowDefinitions>
+        <controls:GridLayout.RowDefinitions>
             <RowDefinition Height="Auto" />
             <RowDefinition Height="Auto" />
             <RowDefinition Height="Auto" />
@@ -32,11 +32,11 @@
             <RowDefinition Height="16"/>
             <RowDefinition Height="Auto" />
             <RowDefinition Height="Auto" />
-        </ui:GridLayout.RowDefinitions>
+        </controls:GridLayout.RowDefinitions>
 
 
-        <Label Grid.Column="0" Content="{x:Static publisher:RawPublisherViewStrings.LabelDeliveryMode}" />
+        <Label Grid.Row="0" Grid.Column="0" Content="{x:Static publisher:RawPublisherViewStrings.LabelDeliveryMode}" />
-        <ComboBox Grid.Column="1" SelectedIndex="{Binding DeliveryModeIndex}">
+        <ComboBox Grid.Row="0" Grid.Column="1" SelectedIndex="{Binding DeliveryModeIndex}">
             <ComboBoxItem Content="{x:Static publisher:RawPublisherViewStrings.DeliveryModeNonPersistent}" />
             <ComboBoxItem Content="{x:Static publisher:RawPublisherViewStrings.DeliveryModePersistent}" />
         </ComboBox>
@@ -132,5 +132,5 @@
 
         <Label Grid.Row="14" Grid.Column="0" Content="{x:Static publisher:RawPublisherViewStrings.LabelPayload}" />
         <publisher:PayloadEditorControl Grid.Row="14" Grid.Column="1" Payload="{Binding Payload}" ContentType="{Binding ContentType}" Height="350"/>
-    </ui:GridLayout>
+    </controls:GridLayout>
 </UserControl>

PettingZoo/UI/Tab/Publisher/RawPublisherView.xaml.cs

@@ -1,8 +1,6 @@
 using System;
-using System.Collections.Generic;
 using System.Linq;
 using System.Windows;
-using System.Windows.Controls;
 using System.Windows.Input;
 using System.Windows.Threading;
 

PettingZoo/UI/Tab/Publisher/RawPublisherViewModel.cs

@@ -7,6 +7,7 @@ using System.Text;
 using System.Windows;
 using System.Windows.Input;
 using PettingZoo.Core.Connection;
+using PettingZoo.WPF.ViewModel;
 
 namespace PettingZoo.UI.Tab.Publisher
 {
@@ -144,7 +145,7 @@ namespace PettingZoo.UI.Tab.Publisher
         protected Header LastHeader;
 
 
-        public RawPublisherViewModel(IConnection connection, IPublishDestination publishDestination, ReceivedMessageInfo? receivedMessage = null)
+        public RawPublisherViewModel(IConnection connection, IPublishDestination publishDestination, BaseMessageInfo? receivedMessage = null)
         {
             this.connection = connection;
             this.publishDestination = publishDestination;
@@ -167,11 +168,11 @@ namespace PettingZoo.UI.Tab.Publisher
 
                 Payload = Encoding.UTF8.GetString(receivedMessage.Body);
 
-                foreach (var header in receivedMessage.Properties.Headers)
+                foreach (var (key, value) in receivedMessage.Properties.Headers)
                     Headers.Add(new Header
                     {
-                        Key = header.Key,
+                        Key = key,
-                        Value = header.Value
+                        Value = value
                     });
 
                 PropertiesExpanded = AnyNotEmpty(AppId, ContentEncoding, Expiration, MessageId, Priority, Timestamp, TypeProperty, UserId);
@@ -244,7 +245,7 @@ namespace PettingZoo.UI.Tab.Publisher
         }
 
 
-        private bool PublishCanExecute()
+        private static bool PublishCanExecute()
         {
             // TODO validate input
             return true;

PettingZoo/UI/Tab/Publisher/TapetiPublisherView.xaml

@@ -4,18 +4,18 @@
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:publisher="clr-namespace:PettingZoo.UI.Tab.Publisher"
-             xmlns:ui="clr-namespace:PettingZoo.UI"
+             xmlns:controls="clr-namespace:PettingZoo.WPF.Controls;assembly=PettingZoo.WPF"
              mc:Ignorable="d" 
              d:DesignHeight="800" d:DesignWidth="800"
              d:DataContext="{d:DesignInstance publisher:DesignTimeTapetiPublisherViewModel, IsDesignTimeCreatable=True}"
              Background="White">
-    <ui:GridLayout Style="{StaticResource Form}">
+    <controls:GridLayout Style="{StaticResource Form}">
         <Grid.ColumnDefinitions>
             <ColumnDefinition Width="Auto" SharedSizeGroup="Label" />
             <ColumnDefinition Width="*" />
         </Grid.ColumnDefinitions>
 
-        <ui:GridLayout.RowDefinitions>
+        <controls:GridLayout.RowDefinitions>
             <RowDefinition Height="Auto" />
             <RowDefinition Height="Auto" />
             <RowDefinition Height="Auto" />
@@ -23,7 +23,7 @@
             <RowDefinition Height="Auto"/>
             <RowDefinition Height="Auto"/>
             <RowDefinition Height="Auto" />
-        </ui:GridLayout.RowDefinitions>
+        </controls:GridLayout.RowDefinitions>
 
 
         <Label Grid.Column="0" Content="{x:Static publisher:TapetiPublisherViewStrings.LabelProperties}" Style="{StaticResource SectionLabel}"/>
@@ -42,12 +42,10 @@
             </Grid.ColumnDefinitions>
 
             <TextBox Grid.Column="0" Text="{Binding ClassName, UpdateSourceTrigger=PropertyChanged}" GotFocus="CaretToEnd" />
-            <!--
+            <Button Grid.Column="1" Content="{x:Static publisher:TapetiPublisherViewStrings.ButtonBrowseClass}" Command="{Binding BrowseClassCommand}" />
-            <Button Grid.Column="1" Content="{x:Static publisher:TapetiPublisherViewStrings.ButtonBrowseClass}" />
-            -->
         </Grid>
 
         <Label Grid.Row="6" Grid.Column="0" Content="{x:Static publisher:TapetiPublisherViewStrings.LabelPayload}" />
         <publisher:PayloadEditorControl Grid.Row="6" Grid.Column="1" Payload="{Binding Payload}" FixedJson="True" Height="350"/>
-    </ui:GridLayout>
+    </controls:GridLayout>
 </UserControl>

PettingZoo/UI/Tab/Publisher/TapetiPublisherViewModel.cs

@@ -1,21 +1,28 @@
 using System.Collections.Generic;
 using System.Text;
+using System.Windows;
 using System.Windows.Input;
+using System.Windows.Threading;
 using PettingZoo.Core.Connection;
+using PettingZoo.Core.Generator;
+using PettingZoo.WPF.ViewModel;
 using IConnection = PettingZoo.Core.Connection.IConnection;
 
 namespace PettingZoo.UI.Tab.Publisher
 {
-    public class TapetiPublisherViewModel : BaseViewModel
+    public class TapetiPublisherViewModel : BaseViewModel, ITabHostWindowNotify
     {
         private readonly IConnection connection;
         private readonly IPublishDestination publishDestination;
+        private readonly IExampleGenerator exampleGenerator;
         private readonly DelegateCommand publishCommand;
+        private readonly DelegateCommand browseClassCommand;
 
         private string correlationId = "";
         private string payload = "";
         private string className = "";
         private string assemblyName = "";
+        private Window? tabHostWindow;
 
 
         public string CorrelationId
@@ -51,6 +58,7 @@ namespace PettingZoo.UI.Tab.Publisher
 
 
         public ICommand PublishCommand => publishCommand;
+        public ICommand BrowseClassCommand => browseClassCommand;
 
 
 
@@ -81,12 +89,14 @@ namespace PettingZoo.UI.Tab.Publisher
         }
 
 
-        public TapetiPublisherViewModel(IConnection connection, IPublishDestination publishDestination, ReceivedMessageInfo? receivedMessage = null)
+        public TapetiPublisherViewModel(IConnection connection, IPublishDestination publishDestination, IExampleGenerator exampleGenerator, ReceivedMessageInfo? receivedMessage = null)
         {
             this.connection = connection;
             this.publishDestination = publishDestination;
+            this.exampleGenerator = exampleGenerator;
 
             publishCommand = new DelegateCommand(PublishExecute, PublishCanExecute);
+            browseClassCommand = new DelegateCommand(BrowseClassExecute);
 
 
             if (receivedMessage == null || !IsTapetiMessage(receivedMessage, out var receivedAssemblyName, out var receivedClassName)) 
@@ -99,6 +109,31 @@ namespace PettingZoo.UI.Tab.Publisher
         }
 
 
+        private void BrowseClassExecute()
+        {
+            exampleGenerator.Select(tabHostWindow, example =>
+            {
+                Dispatcher.CurrentDispatcher.BeginInvoke(() =>
+                {
+                    switch (example)
+                    {
+                        case null:
+                            return;
+
+                        case IClassTypeExample classTypeExample:
+                            AssemblyName = classTypeExample.AssemblyName;
+                            ClassName = classTypeExample.FullClassName;
+                            break;
+                    }
+
+                    Payload = example.Generate();
+
+                    // TODO if validating example, keep reference for validation... and implement validation of course
+                });
+            });
+        }
+
+
         private void PublishExecute()
         {
             static string? NullIfEmpty(string? value)
@@ -125,17 +160,22 @@ namespace PettingZoo.UI.Tab.Publisher
         }
 
 
-        private bool PublishCanExecute()
+        private static bool PublishCanExecute()
         {
             // TODO validate input
             return true;
         }
+
+        public void HostWindowChanged(Window? hostWindow)
+        {
+            tabHostWindow = hostWindow;
+        }
     }
 
 
     public class DesignTimeTapetiPublisherViewModel : TapetiPublisherViewModel
     {
-        public DesignTimeTapetiPublisherViewModel() : base(null!, null!)
+        public DesignTimeTapetiPublisherViewModel() : base(null!, null!, null!)
         {
             AssemblyName = "Messaging.Example";
             ClassName = "Messaging.Example.ExampleMessage";

PettingZoo/UI/Tab/Subscriber/SubscriberView.xaml.cs

@@ -1,5 +1,4 @@
-using System.Collections.Generic;
+using System.Windows;
-using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Media;
 

PettingZoo/UI/Tab/Subscriber/SubscriberViewModel.cs

@@ -6,6 +6,7 @@ using System.Threading.Tasks;
 using System.Windows.Input;
 using PettingZoo.Core.Connection;
 using PettingZoo.Core.Rendering;
+using PettingZoo.WPF.ViewModel;
 
 // TODO visual hint of where the last read message was when activating the tab again
 

PettingZoo/UI/Tab/Undocked/UndockedTabHostViewModel.cs

@@ -1,10 +1,10 @@
-using System;
+using System.Collections.Generic;
-using System.Collections.Generic;
 using System.ComponentModel;
 using System.Linq;
 using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Input;
+using PettingZoo.WPF.ViewModel;
 
 namespace PettingZoo.UI.Tab.Undocked
 {
@@ -17,7 +17,7 @@ namespace PettingZoo.UI.Tab.Undocked
 
         public string Title => tab.Title;
         public ContentControl Content => tab.Content;
-        public IEnumerable<TabToolbarCommand> ToolbarCommands => tab.ToolbarCommands;
+        public IEnumerable<TabToolbarCommand> ToolbarCommands => (tab as ITabToolbarCommands)?.ToolbarCommands ?? Enumerable.Empty<TabToolbarCommand>();
 
         public Visibility ToolbarCommandsSeparatorVisibility =>
             ToolbarCommands.Any() ? Visibility.Visible : Visibility.Collapsed;
@@ -63,23 +63,12 @@ namespace PettingZoo.UI.Tab.Undocked
 
         private class DesignTimeTab : ITab
         {
+            #pragma warning disable CS0067 // "The event ... is never used" - it's part of the interface so it's required.
             public event PropertyChangedEventHandler? PropertyChanged;
-            public IEnumerable<TabToolbarCommand> ToolbarCommands { get; } = Array.Empty<TabToolbarCommand>();
+            #pragma warning restore CS0067
 
             public string Title => "Design-time tab title";
             public ContentControl Content => null!;
-
-
-            public void Activate()
-            {
-                // Just to prevent the "PropertyChanged is never used" message
-                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(null));
-            }
-
-
-            public void Deactivate()
-            {
-            }
         }
     }
 }

PettingZoo/UI/Tab/ViewTab.cs

@@ -3,12 +3,12 @@ using System.Collections.Generic;
 using System.ComponentModel;
 using System.Linq;
 using System.Linq.Expressions;
+using System.Windows;
 using System.Windows.Controls;
-using System.Windows.Input;
 
 namespace PettingZoo.UI.Tab
 {
-    public class ViewTab<TView, TViewModel> : ITab where TView : ContentControl where TViewModel : INotifyPropertyChanged
+    public class ViewTab<TView, TViewModel> : ITab, ITabToolbarCommands, ITabActivate, ITabHostWindowNotify where TView : ContentControl where TViewModel : INotifyPropertyChanged
     {
         public string Title => getTitle(viewModel);
         public ContentControl Content { get; }
@@ -57,5 +57,11 @@ namespace PettingZoo.UI.Tab
         {
             (viewModel as ITabActivate)?.Deactivate();
         }
+
+
+        public void HostWindowChanged(Window? hostWindow)
+        {
+            (viewModel as ITabHostWindowNotify)?.HostWindowChanged(hostWindow);
+        }
     }
 }

PettingZoo/UI/Tab/ViewTabFactory.cs

@@ -1,5 +1,5 @@
-using System.Windows.Input;
+using PettingZoo.Core.Connection;
-using PettingZoo.Core.Connection;
+using PettingZoo.Core.Generator;
 using PettingZoo.UI.Tab.Publisher;
 using PettingZoo.UI.Tab.Subscriber;
 
@@ -8,11 +8,13 @@ namespace PettingZoo.UI.Tab
     public class ViewTabFactory : ITabFactory
     {
         private readonly ITabHost tabHost;
+        private readonly IExampleGenerator exampleGenerator;
 
 
-        public ViewTabFactory(ITabHost tabHost)
+        public ViewTabFactory(ITabHost tabHost, IExampleGenerator exampleGenerator)
         {
             this.tabHost = tabHost;
+            this.exampleGenerator = exampleGenerator;
         }
 
 
@@ -28,7 +30,7 @@ namespace PettingZoo.UI.Tab
         
         public ITab CreatePublisherTab(IConnection connection, ReceivedMessageInfo? fromReceivedMessage = null)
         {
-            var viewModel = new PublisherViewModel(tabHost, this, connection, fromReceivedMessage);
+            var viewModel = new PublisherViewModel(tabHost, this, connection, exampleGenerator, fromReceivedMessage);
             return new ViewTab<PublisherView, PublisherViewModel>(
                 new PublisherView(viewModel),
                 viewModel,