diff --git a/PettingZoo.Tapeti/TapetiClassLibraryExampleGenerator.cs b/PettingZoo.Tapeti/TapetiClassLibraryExampleGenerator.cs
index ef2b4e7..038daa3 100644
--- a/PettingZoo.Tapeti/TapetiClassLibraryExampleGenerator.cs
+++ b/PettingZoo.Tapeti/TapetiClassLibraryExampleGenerator.cs
@@ -54,12 +54,13 @@ namespace PettingZoo.Tapeti
                     progressWindow.Top = windowBounds.Top + (windowBounds.Height - progressWindow.Height) / 2;
                     progressWindow.Show();
 
+                    var cancellationToken = progressWindow.CancellationToken;
+
                     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 assemblies = await args.Assemblies.GetAssemblies(progressWindow, cancellationToken);
 
                             // var classes = 
                             var examples = LoadExamples(assemblies);
@@ -94,10 +95,11 @@ namespace PettingZoo.Tapeti
                                 // ReSharper disable once ConstantConditionalAccessQualifier - if I remove it, there's a "Dereference of a possibly null reference" warning instead
                                 progressWindow?.Close();
 
-                                MessageBox.Show($"Error while loading assembly: {e.Message}", "Petting Zoo - Exception", MessageBoxButton.OK, MessageBoxImage.Error);
+                                if (e is not OperationCanceledException)
+                                    MessageBox.Show($"Error while loading assembly: {e.Message}", "Petting Zoo - Exception", MessageBoxButton.OK, MessageBoxImage.Error);
                             });
                         }
-                    });
+                    }, CancellationToken.None);
                 });
             };
 
diff --git a/PettingZoo.Tapeti/TypeToJObjectConverter.cs b/PettingZoo.Tapeti/TypeToJObjectConverter.cs
index 2bb652f..7efcd8e 100644
--- a/PettingZoo.Tapeti/TypeToJObjectConverter.cs
+++ b/PettingZoo.Tapeti/TypeToJObjectConverter.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
+using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
 
 namespace PettingZoo.Tapeti
@@ -59,7 +60,20 @@ namespace PettingZoo.Tapeti
                 actualType = equivalentType;
 
 
-            // TODO check for JsonConverter attribute? doubt we'll be able to generate a nice value for it, but at least we can provide a placeholder
+            try
+            {
+                if (type.GetCustomAttribute<JsonConverterAttribute>() != null)
+                {
+                    // This type uses custom Json conversion so there's no way to know how to provide an example.
+                    // We could try to create an instance of the type and pass it through the converter, but for now we'll
+                    // just output a placeholder.
+                    return "<custom JsonConverter - manual input required>";
+                }
+            }
+            catch
+            {
+                // Move along
+            }
 
             // String is also a class
             if (actualType == typeof(string))
diff --git a/PettingZoo.Tapeti/UI/PackageProgress/PackageProgressStrings.Designer.cs b/PettingZoo.Tapeti/UI/PackageProgress/PackageProgressStrings.Designer.cs
index e0b38ff..6a82b2a 100644
--- a/PettingZoo.Tapeti/UI/PackageProgress/PackageProgressStrings.Designer.cs
+++ b/PettingZoo.Tapeti/UI/PackageProgress/PackageProgressStrings.Designer.cs
@@ -60,6 +60,15 @@ namespace PettingZoo.Tapeti.UI.PackageProgress {
             }
         }
         
+        /// <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 Reading message classes....
         /// </summary>
diff --git a/PettingZoo.Tapeti/UI/PackageProgress/PackageProgressStrings.resx b/PettingZoo.Tapeti/UI/PackageProgress/PackageProgressStrings.resx
index 1d6d493..eccbf8f 100644
--- a/PettingZoo.Tapeti/UI/PackageProgress/PackageProgressStrings.resx
+++ b/PettingZoo.Tapeti/UI/PackageProgress/PackageProgressStrings.resx
@@ -112,11 +112,14 @@
     <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>
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=6.0.0.0, 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>
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
   </resheader>
+  <data name="ButtonCancel" xml:space="preserve">
+    <value>Cancel</value>
+  </data>
   <data name="WindowTitle" xml:space="preserve">
     <value>Reading message classes...</value>
   </data>
diff --git a/PettingZoo.Tapeti/UI/PackageProgress/PackageProgressWindow.xaml b/PettingZoo.Tapeti/UI/PackageProgress/PackageProgressWindow.xaml
index 45ccb52..aef7232 100644
--- a/PettingZoo.Tapeti/UI/PackageProgress/PackageProgressWindow.xaml
+++ b/PettingZoo.Tapeti/UI/PackageProgress/PackageProgressWindow.xaml
@@ -5,10 +5,13 @@
         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" />
+        WindowStyle="ToolWindow"
+        SizeToContent="Height">
+    <StackPanel Orientation="Vertical">
+        <ProgressBar Height="25" Margin="16" VerticalAlignment="Center" Name="Progress" Maximum="100" />
+        <Button HorizontalAlignment="Center" Margin="0,0,0,16" Content="{x:Static packageProgress:PackageProgressStrings.ButtonCancel}" Click="CancelButton_OnClick" />
+    </StackPanel>
 </Window>
diff --git a/PettingZoo.Tapeti/UI/PackageProgress/PackageProgressWindow.xaml.cs b/PettingZoo.Tapeti/UI/PackageProgress/PackageProgressWindow.xaml.cs
index cf8e15b..7ff449f 100644
--- a/PettingZoo.Tapeti/UI/PackageProgress/PackageProgressWindow.xaml.cs
+++ b/PettingZoo.Tapeti/UI/PackageProgress/PackageProgressWindow.xaml.cs
@@ -1,4 +1,7 @@
 using System;
+using System.Threading;
+using System.Windows;
+using System.Windows.Controls;
 
 namespace PettingZoo.Tapeti.UI.PackageProgress
 {
@@ -7,9 +10,19 @@ namespace PettingZoo.Tapeti.UI.PackageProgress
     /// </summary>
     public partial class PackageProgressWindow : IProgress<int>
     {
+        private readonly CancellationTokenSource cancellationTokenSource = new();
+
+        public CancellationToken CancellationToken => cancellationTokenSource.Token;
+
+
         public PackageProgressWindow()
         {
             InitializeComponent();
+
+            Closed += (_, _) =>
+            {
+                cancellationTokenSource.Cancel();
+            };
         }
 
 
@@ -20,5 +33,11 @@ namespace PettingZoo.Tapeti.UI.PackageProgress
                 Progress.Value = value;
             });
         }
+
+        private void CancelButton_OnClick(object sender, RoutedEventArgs e)
+        {
+            cancellationTokenSource.Cancel();
+            ((Button)sender).IsEnabled = false;
+        }
     }
 }
diff --git a/PettingZoo.Tapeti/UI/PackageSelection/PackageSelectionViewModel.cs b/PettingZoo.Tapeti/UI/PackageSelection/PackageSelectionViewModel.cs
index 2e0adc4..f690090 100644
--- a/PettingZoo.Tapeti/UI/PackageSelection/PackageSelectionViewModel.cs
+++ b/PettingZoo.Tapeti/UI/PackageSelection/PackageSelectionViewModel.cs
@@ -88,7 +88,6 @@ namespace PettingZoo.Tapeti.UI.PackageSelection
         public ICommand AssemblyBrowse => assemblyBrowse;
 
 
-        // TODO hint for extra assemblies path
         public static string HintNuGetSources => string.Format(PackageSelectionStrings.HintNuGetSources, PettingZooPaths.InstallationRoot, PettingZooPaths.AppDataRoot);
 
         public string NuGetSearchTerm
diff --git a/PettingZoo/TODO.md b/PettingZoo/TODO.md
index ebf7a31..51bc24c 100644
--- a/PettingZoo/TODO.md
+++ b/PettingZoo/TODO.md
@@ -1,12 +1,12 @@
 Must-have
 ---------
-- Check required fields before enabling Publish button
 
 
 Should-have
 -----------
 - Save / load publisher messages (either as templates or to disk)
 - Tapeti: export received messages to Tapeti.Cmd JSON file / Tapeti.Cmd command-line
+- Tapeti: import Tapeti.Cmd JSON file into Subscriber-esque tab for easier browsing
 - Tapeti: fetch NuGet dependencies to improve the chances of succesfully loading the assembly, instead of the current "extraAssembliesPaths" workaround
 
 
diff --git a/PettingZoo/UI/Tab/Publisher/PublisherViewModel.cs b/PettingZoo/UI/Tab/Publisher/PublisherViewModel.cs
index 4b5b350..04f6ba8 100644
--- a/PettingZoo/UI/Tab/Publisher/PublisherViewModel.cs
+++ b/PettingZoo/UI/Tab/Publisher/PublisherViewModel.cs
@@ -45,7 +45,9 @@ namespace PettingZoo.UI.Tab.Publisher
         public bool SendToExchange
         {
             get => sendToExchange;
-            set => SetField(ref sendToExchange, value, otherPropertiesChanged: new[] { nameof(SendToQueue), nameof(ExchangeVisibility), nameof(QueueVisibility), nameof(Title) });
+            set => SetField(ref sendToExchange, value, 
+                delegateCommandsChanged: new [] { publishCommand },
+                otherPropertiesChanged: new[] { nameof(SendToQueue), nameof(ExchangeVisibility), nameof(QueueVisibility), nameof(Title) });
         }
 
 
@@ -59,21 +61,21 @@ namespace PettingZoo.UI.Tab.Publisher
         public string Exchange
         {
             get => exchange;
-            set => SetField(ref exchange, value);
+            set => SetField(ref exchange, value, delegateCommandsChanged: new[] { publishCommand });
         }
 
 
         public string RoutingKey
         {
             get => routingKey;
-            set => SetField(ref routingKey, value, otherPropertiesChanged: new[] { nameof(Title) });
+            set => SetField(ref routingKey, value, delegateCommandsChanged: new[] { publishCommand }, otherPropertiesChanged: new[] { nameof(Title) });
         }
 
 
         public string Queue
         {
             get => queue;
-            set => SetField(ref queue, value, otherPropertiesChanged: new[] { nameof(Title) });
+            set => SetField(ref queue, value, delegateCommandsChanged: new[] { publishCommand }, otherPropertiesChanged: new[] { nameof(Title) });
         }
 
 
@@ -183,6 +185,17 @@ namespace PettingZoo.UI.Tab.Publisher
 
         private bool PublishCanExecute()
         {
+            if (SendToExchange)
+            {
+                if (string.IsNullOrWhiteSpace(Exchange) || string.IsNullOrWhiteSpace(RoutingKey))
+                    return false;
+            }
+            else
+            {
+                if (string.IsNullOrWhiteSpace(Queue))
+                    return false;
+            }
+
             return messageTypePublishCommand?.CanExecute(null) ?? false;
         }
 
@@ -197,6 +210,11 @@ namespace PettingZoo.UI.Tab.Publisher
                     if (rawPublisherView == null)
                     {
                         rawPublisherViewModel = new RawPublisherViewModel(connection, this);
+                        rawPublisherViewModel.PublishCommand.CanExecuteChanged += (_, _) =>
+                        {
+                            publishCommand.RaiseCanExecuteChanged();
+                        };
+
                         rawPublisherView ??= new RawPublisherView(rawPublisherViewModel);
                     }
                     else
@@ -213,6 +231,11 @@ namespace PettingZoo.UI.Tab.Publisher
                     if (tapetiPublisherView == null)
                     {
                         tapetiPublisherViewModel = new TapetiPublisherViewModel(connection, this, exampleGenerator);
+                        tapetiPublisherViewModel.PublishCommand.CanExecuteChanged += (_, _) =>
+                        {
+                            publishCommand.RaiseCanExecuteChanged();
+                        };
+
                         tapetiPublisherView ??= new TapetiPublisherView(tapetiPublisherViewModel);
 
                         if (tabHostWindow != null)
diff --git a/PettingZoo/UI/Tab/Publisher/RawPublisherViewModel.cs b/PettingZoo/UI/Tab/Publisher/RawPublisherViewModel.cs
index 1be1697..1396c1e 100644
--- a/PettingZoo/UI/Tab/Publisher/RawPublisherViewModel.cs
+++ b/PettingZoo/UI/Tab/Publisher/RawPublisherViewModel.cs
@@ -115,7 +115,7 @@ namespace PettingZoo.UI.Tab.Publisher
         public string Payload
         {
             get => payload;
-            set => SetField(ref payload, value);
+            set => SetField(ref payload, value, delegateCommandsChanged: new [] { publishCommand });
         }
 
 
@@ -267,10 +267,9 @@ namespace PettingZoo.UI.Tab.Publisher
         }
 
 
-        private static bool PublishCanExecute()
+        private bool PublishCanExecute()
         {
-            // TODO validate input
-            return true;
+            return !string.IsNullOrWhiteSpace(Payload);
         }
 
 
diff --git a/PettingZoo/UI/Tab/Publisher/TapetiPublisherViewModel.cs b/PettingZoo/UI/Tab/Publisher/TapetiPublisherViewModel.cs
index 202fdc3..9e848d8 100644
--- a/PettingZoo/UI/Tab/Publisher/TapetiPublisherViewModel.cs
+++ b/PettingZoo/UI/Tab/Publisher/TapetiPublisherViewModel.cs
@@ -36,10 +36,15 @@ namespace PettingZoo.UI.Tab.Publisher
 
         public string ClassName
         {
-            get => string.IsNullOrEmpty(className) ? AssemblyName + "." : className;
+            get => string.IsNullOrWhiteSpace(className) 
+                ? string.IsNullOrWhiteSpace(AssemblyName) 
+                    ? "" 
+                    : AssemblyName + "." 
+                : className;
+
             set
             {
-                if (SetField(ref className, value))
+                if (SetField(ref className, value, delegateCommandsChanged: new[] { publishCommand }))
                     validatingExample = null;
             }
         }
@@ -48,7 +53,7 @@ namespace PettingZoo.UI.Tab.Publisher
         public string AssemblyName
         {
             get => assemblyName;
-            set => SetField(ref assemblyName, value, otherPropertiesChanged:
+            set => SetField(ref assemblyName, value, delegateCommandsChanged: new[] { publishCommand }, otherPropertiesChanged:
                 string.IsNullOrEmpty(value) || string.IsNullOrEmpty(className)
                     ? new [] { nameof(ClassName) } 
                     : null
@@ -59,7 +64,7 @@ namespace PettingZoo.UI.Tab.Publisher
         public string Payload
         {
             get => payload;
-            set => SetField(ref payload, value);
+            set => SetField(ref payload, value, delegateCommandsChanged: new[] { publishCommand });
         }
 
 
@@ -164,12 +169,15 @@ namespace PettingZoo.UI.Tab.Publisher
         }
 
 
-        private static bool PublishCanExecute()
+        private bool PublishCanExecute()
         {
-            // TODO validate input
-            return true;
+            return
+                !string.IsNullOrWhiteSpace(assemblyName) &&
+                !string.IsNullOrWhiteSpace(ClassName) && 
+                !string.IsNullOrWhiteSpace(Payload);
         }
 
+
         public void HostWindowChanged(Window? hostWindow)
         {
             tabHostWindow = hostWindow;
diff --git a/PettingZoo/UI/Tab/Subscriber/SubscriberView.xaml b/PettingZoo/UI/Tab/Subscriber/SubscriberView.xaml
index 87691f1..7221422 100644
--- a/PettingZoo/UI/Tab/Subscriber/SubscriberView.xaml
+++ b/PettingZoo/UI/Tab/Subscriber/SubscriberView.xaml
@@ -7,6 +7,7 @@
              xmlns:res="clr-namespace:PettingZoo.UI.Tab.Subscriber"
              xmlns:svgc="http://sharpvectors.codeplex.com/svgc/"
              xmlns:avalonedit="http://icsharpcode.net/sharpdevelop/avalonedit"
+             xmlns:connection="clr-namespace:PettingZoo.Core.Connection;assembly=PettingZoo.Core"
              mc:Ignorable="d" 
              d:DesignHeight="450" 
              d:DesignWidth="800"
@@ -24,48 +25,46 @@
         <ListBox Grid.Column="0" Grid.Row="0" 
                      HorizontalAlignment="Stretch" 
                      HorizontalContentAlignment="Stretch"
-                     ItemsSource="{Binding Messages}" 
                      SelectedItem="{Binding Path=SelectedMessage, Mode=TwoWay}"
                      ui:ListBox.AutoScroll="True"
-                     x:Name="ReferenceControlForBorder">
+                     x:Name="ReferenceControlForBorder"
+                     Grid.IsSharedSizeScope="True">
             <ListBox.Resources>
                 <ui:BindingProxy x:Key="ContextMenuProxy" Data="{Binding}" />
+                <CollectionViewSource x:Key="Messages"
+                                      Source="{Binding Messages}" />
+                <CollectionViewSource x:Key="UnreadMessages"
+                                      Source="{Binding UnreadMessages}" />
             </ListBox.Resources>
-            <ListBox.ItemTemplate>
-                <DataTemplate>
-                    <Grid>
-                        <Grid.ColumnDefinitions>
-                            <ColumnDefinition Width="Auto" MinWidth="150" SharedSizeGroup="DateTime"/>
-                            <ColumnDefinition Width="*" />
-                        </Grid.ColumnDefinitions>
-
-                        <Grid.RowDefinitions>
-                            <RowDefinition Height="Auto" />
-                            <RowDefinition Height="Auto" />
-                        </Grid.RowDefinitions>
-
-                        <!-- TODO insert as non-focusable item instead, so it's not part of the selection (and perhaps also fixes the bug mentioned in SubscriberViewModel) -->
-                        <Grid Grid.Column="0" Grid.Row="0" Grid.ColumnSpan="2">
+            <ListBox.ItemsSource>
+                <CompositeCollection>
+                    <CollectionContainer Collection="{Binding Source={StaticResource Messages}}" />
+                    <ListBoxItem HorizontalContentAlignment="Stretch" IsEnabled="False" IsHitTestVisible="False">
+                        <Grid Visibility="{Binding UnreadMessagesVisibility}">
                             <Grid.ColumnDefinitions>
                                 <ColumnDefinition SharedSizeGroup="DateTime" />
                                 <ColumnDefinition Width="Auto" />
                                 <ColumnDefinition Width="*" />
                             </Grid.ColumnDefinitions>
 
-                            <Grid.Visibility>
-                                <MultiBinding Converter="{StaticResource SameMessageVisibilityConverter}">
-                                    <Binding RelativeSource="{RelativeSource Self}" Path="DataContext" />
-                                    <Binding RelativeSource="{RelativeSource AncestorType={x:Type ListBox}}" Path="DataContext.NewMessage" />
-                                </MultiBinding>
-                            </Grid.Visibility>
-
                             <Separator Grid.Column="0" Margin="0,0,8,0" />
                             <TextBlock Grid.Column="1" Text="{x:Static res:SubscriberViewStrings.LabelNewMessages}" HorizontalAlignment="Center" Background="{Binding Background, RelativeSource={RelativeSource AncestorType={x:Type ListBoxItem}}}" Foreground="{x:Static SystemColors.GrayTextBrush}" />
                             <Separator Grid.Column="2" Margin="8,0,0,0" />
-                        </Grid>
+                        </Grid>                    
+                    </ListBoxItem>
+                    <CollectionContainer Collection="{Binding Source={StaticResource UnreadMessages}}" />
+                </CompositeCollection>
+            </ListBox.ItemsSource>
+            <ListBox.ItemTemplate>
+                <DataTemplate DataType="{x:Type connection:ReceivedMessageInfo}">
+                    <Grid>
+                        <Grid.ColumnDefinitions>
+                            <ColumnDefinition Width="Auto" MinWidth="150" SharedSizeGroup="DateTime"/>
+                            <ColumnDefinition Width="*" />
+                        </Grid.ColumnDefinitions>
 
-                        <TextBlock Grid.Column="0" Grid.Row="1" Text="{Binding ReceivedTimestamp, StringFormat=g}" Style="{StaticResource Timestamp}" />
-                        <TextBlock Grid.Column="1" Grid.Row="1" Text="{Binding RoutingKey}" Style="{StaticResource RoutingKey}" />
+                        <TextBlock Grid.Column="0" Text="{Binding ReceivedTimestamp, StringFormat=g}" Style="{StaticResource Timestamp}" />
+                        <TextBlock Grid.Column="1" Text="{Binding RoutingKey}" Style="{StaticResource RoutingKey}" />
 
                         <Grid.ContextMenu>
                             <ContextMenu>
diff --git a/PettingZoo/UI/Tab/Subscriber/SubscriberViewModel.cs b/PettingZoo/UI/Tab/Subscriber/SubscriberViewModel.cs
index 99b91fa..44adf43 100644
--- a/PettingZoo/UI/Tab/Subscriber/SubscriberViewModel.cs
+++ b/PettingZoo/UI/Tab/Subscriber/SubscriberViewModel.cs
@@ -1,17 +1,15 @@
 using System;
 using System.Collections.Generic;
-using System.Collections.ObjectModel;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
+using System.Windows;
 using System.Windows.Input;
 using System.Windows.Threading;
 using PettingZoo.Core.Connection;
 using PettingZoo.Core.Rendering;
 using PettingZoo.WPF.ViewModel;
 
-// TODO if the "New message" line is visible when this tab is undocked, the line in the ListBox does not shrink. Haven't been able to figure out yet how to solve it
-
 namespace PettingZoo.UI.Tab.Subscriber
 {
     public class SubscriberViewModel : BaseViewModel, ITabToolbarCommands, ITabActivate
@@ -29,7 +27,6 @@ namespace PettingZoo.UI.Tab.Subscriber
         private readonly DelegateCommand createPublisherCommand;
 
         private bool tabActive;
-        private ReceivedMessageInfo? newMessage;
         private Timer? newMessageTimer;
         private int unreadCount;
 
@@ -39,7 +36,8 @@ namespace PettingZoo.UI.Tab.Subscriber
         // ReSharper disable once UnusedMember.Global - it is, but via a proxy
         public ICommand CreatePublisherCommand => createPublisherCommand;
 
-        public ObservableCollection<ReceivedMessageInfo> Messages { get; }
+        public ObservableCollectionEx<ReceivedMessageInfo> Messages { get; }
+        public ObservableCollectionEx<ReceivedMessageInfo> UnreadMessages { get; }
 
         public ReceivedMessageInfo? SelectedMessage
         {
@@ -52,11 +50,7 @@ namespace PettingZoo.UI.Tab.Subscriber
         }
 
 
-        public ReceivedMessageInfo? NewMessage
-        {
-            get => newMessage;
-            set => SetField(ref newMessage, value);
-        }
+        public Visibility UnreadMessagesVisibility => UnreadMessages.Count > 0 ? Visibility.Visible : Visibility.Collapsed;
 
 
         public string SelectedMessageBody =>
@@ -85,7 +79,8 @@ namespace PettingZoo.UI.Tab.Subscriber
 
             dispatcher = Dispatcher.CurrentDispatcher;
 
-            Messages = new ObservableCollection<ReceivedMessageInfo>();
+            Messages = new ObservableCollectionEx<ReceivedMessageInfo>();
+            UnreadMessages = new ObservableCollectionEx<ReceivedMessageInfo>();
             clearCommand = new DelegateCommand(ClearExecute, ClearCanExecute);
 
             toolbarCommands = new[]
@@ -103,6 +98,8 @@ namespace PettingZoo.UI.Tab.Subscriber
         private void ClearExecute()
         {
             Messages.Clear();
+            UnreadMessages.Clear();
+            RaisePropertyChanged(nameof(UnreadMessagesVisibility));
             clearCommand.RaiseCanExecuteChanged();
         }
 
@@ -135,10 +132,13 @@ namespace PettingZoo.UI.Tab.Subscriber
                     unreadCount++;
                     RaisePropertyChanged(nameof(Title));
 
-                    NewMessage ??= args.MessageInfo;
+                    UnreadMessages.Add(args.MessageInfo);
+                    if (UnreadMessages.Count == 1)
+                        RaisePropertyChanged(nameof(UnreadMessagesVisibility));
                 }
+                else
+                    Messages.Add(args.MessageInfo);
 
-                Messages.Add(args.MessageInfo);
                 clearCommand.RaiseCanExecuteChanged();
             });
         }
@@ -161,7 +161,7 @@ namespace PettingZoo.UI.Tab.Subscriber
 
             RaisePropertyChanged(nameof(Title));
 
-            if (NewMessage == null) 
+            if (UnreadMessages.Count == 0) 
                 return;
 
             newMessageTimer?.Dispose();
@@ -170,7 +170,23 @@ namespace PettingZoo.UI.Tab.Subscriber
                 {
                     dispatcher.BeginInvoke(() =>
                     {
-                        NewMessage = null;
+                        if (UnreadMessages.Count == 0)
+                            return;
+
+                        Messages.BeginUpdate();
+                        UnreadMessages.BeginUpdate();
+                        try
+                        {
+                            Messages.AddRange(UnreadMessages);
+                            UnreadMessages.Clear();
+                        }
+                        finally
+                        {
+                            UnreadMessages.EndUpdate();
+                            Messages.EndUpdate();
+                        }
+
+                        RaisePropertyChanged(nameof(UnreadMessagesVisibility));
                     });
                 },
                 null,
@@ -178,6 +194,7 @@ namespace PettingZoo.UI.Tab.Subscriber
                 Timeout.InfiniteTimeSpan);
         }
 
+
         public void Deactivate()
         {
             if (newMessageTimer != null)
@@ -186,7 +203,6 @@ namespace PettingZoo.UI.Tab.Subscriber
                 newMessageTimer = null;
             }
 
-            NewMessage = null;
             tabActive = false;
         }
     }
@@ -197,22 +213,21 @@ namespace PettingZoo.UI.Tab.Subscriber
         public DesignTimeSubscriberViewModel() : base(null!, null!, null!, new DesignTimeSubscriber())
         {
             for (var i = 1; i <= 5; i++)
-                Messages.Add(new ReceivedMessageInfo(
-                    "designtime", 
-                    $"designtime.message.{i}", 
-                    Encoding.UTF8.GetBytes(@"Design-time message"), 
+                (i > 2 ? UnreadMessages : Messages).Add(new ReceivedMessageInfo(
+                    "designtime",
+                    $"designtime.message.{i}",
+                    Encoding.UTF8.GetBytes(@"Design-time message"),
                     new MessageProperties(null)
                     {
                         ContentType = "text/fake",
                         ReplyTo = "/dev/null"
-                    }, 
+                    },
                     DateTime.Now));
 
-            SelectedMessage = Messages[2];
-            NewMessage = Messages[2];
+            SelectedMessage = UnreadMessages[0];
         }
-        
-        
+
+
         private class DesignTimeSubscriber : ISubscriber
         {
             public ValueTask DisposeAsync()