Introduce message bus to start decoupling components

.editorconfig

@@ -120,6 +120,51 @@ csharp_space_between_method_declaration_parameter_list_parentheses = false
 csharp_space_between_parentheses = false
 csharp_space_between_square_brackets = false
 
+# Naming rules
+dotnet_naming_rule.constants_rule.severity = warning
+dotnet_naming_rule.constants_rule.style = upper_camel_case_style
+dotnet_naming_rule.constants_rule.symbols = constants_symbols
+dotnet_naming_rule.private_constants_rule.severity = warning
+dotnet_naming_rule.private_constants_rule.style = upper_camel_case_style
+dotnet_naming_rule.private_constants_rule.symbols = private_constants_symbols
+dotnet_naming_rule.private_instance_fields_rule.severity = warning
+dotnet_naming_rule.private_instance_fields_rule.style = lower_camel_case_style
+dotnet_naming_rule.private_instance_fields_rule.symbols = private_instance_fields_symbols
+dotnet_naming_rule.private_static_fields_rule.severity = warning
+dotnet_naming_rule.private_static_fields_rule.style = lower_camel_case_style
+dotnet_naming_rule.private_static_fields_rule.symbols = private_static_fields_symbols
+dotnet_naming_rule.private_static_readonly_rule.severity = warning
+dotnet_naming_rule.private_static_readonly_rule.style = upper_camel_case_style
+dotnet_naming_rule.private_static_readonly_rule.symbols = private_static_readonly_symbols
+dotnet_naming_rule.public_static_fields_rule.severity = warning
+dotnet_naming_rule.public_static_fields_rule.style = lower_camel_case_style
+dotnet_naming_rule.public_static_fields_rule.symbols = public_static_fields_symbols
+dotnet_naming_rule.static_readonly_rule.severity = warning
+dotnet_naming_rule.static_readonly_rule.style = upper_camel_case_style
+dotnet_naming_rule.static_readonly_rule.symbols = static_readonly_symbols
+dotnet_naming_style.lower_camel_case_style.capitalization = camel_case
+dotnet_naming_style.upper_camel_case_style.capitalization = pascal_case
+dotnet_naming_symbols.constants_symbols.applicable_accessibilities = public,internal,protected,protected_internal,private_protected
+dotnet_naming_symbols.constants_symbols.applicable_kinds = field
+dotnet_naming_symbols.constants_symbols.required_modifiers = const
+dotnet_naming_symbols.private_constants_symbols.applicable_accessibilities = private
+dotnet_naming_symbols.private_constants_symbols.applicable_kinds = field
+dotnet_naming_symbols.private_constants_symbols.required_modifiers = const
+dotnet_naming_symbols.private_instance_fields_symbols.applicable_accessibilities = private
+dotnet_naming_symbols.private_instance_fields_symbols.applicable_kinds = field
+dotnet_naming_symbols.private_static_fields_symbols.applicable_accessibilities = private
+dotnet_naming_symbols.private_static_fields_symbols.applicable_kinds = field
+dotnet_naming_symbols.private_static_fields_symbols.required_modifiers = static
+dotnet_naming_symbols.private_static_readonly_symbols.applicable_accessibilities = private
+dotnet_naming_symbols.private_static_readonly_symbols.applicable_kinds = field
+dotnet_naming_symbols.private_static_readonly_symbols.required_modifiers = readonly,static
+dotnet_naming_symbols.public_static_fields_symbols.applicable_accessibilities = public,internal,protected,protected_internal,private_protected
+dotnet_naming_symbols.public_static_fields_symbols.applicable_kinds = field
+dotnet_naming_symbols.public_static_fields_symbols.required_modifiers = static
+dotnet_naming_symbols.static_readonly_symbols.applicable_accessibilities = public,internal,protected,protected_internal,private_protected
+dotnet_naming_symbols.static_readonly_symbols.applicable_kinds = field
+dotnet_naming_symbols.static_readonly_symbols.required_modifiers = readonly,static
+
 # Errors and warnings
 
 # MEF006: No importing constructor

ICSharpCode.ILSpyX/TreeView/SharpTreeNode.cs

@@ -182,7 +182,7 @@ namespace ICSharpCode.ILSpyX.TreeView
 		#endregion
 
 		#region OnChildrenChanged
-		internal protected virtual void OnChildrenChanged(NotifyCollectionChangedEventArgs e)
+		protected internal virtual void OnChildrenChanged(NotifyCollectionChangedEventArgs e)
 		{
 			if (e.OldItems != null)
 			{

ILSpy/Analyzers/AnalyzeCommand.cs

@@ -18,27 +18,18 @@
 
 using System.ComponentModel.Composition;
 using System.Linq;
-using System.Windows;
 
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.ILSpy.Properties;
 using ICSharpCode.ILSpy.TreeNodes;
 
-using TomsToolbox.Composition;
-
 namespace ICSharpCode.ILSpy.Analyzers
 {
 	[ExportContextMenuEntry(Header = nameof(Resources.Analyze), Icon = "Images/Search", Category = nameof(Resources.Analyze), InputGestureText = "Ctrl+R", Order = 100)]
 	[PartCreationPolicy(CreationPolicy.Shared)]
 	internal sealed class AnalyzeCommand : SimpleCommand, IContextMenuEntry
 	{
-		private static readonly IExport<AnalyzerTreeView> analyzerTreeViewExport = App.ExportProvider.GetExports<AnalyzerTreeView>().Single();
-
-		private static AnalyzerTreeView AnalyzerTreeView {
-			get {
-				return Application.Current?.MainWindow?.IsLoaded != true ? null : analyzerTreeViewExport.Value;
-			}
-		}
+		private static readonly AnalyzerTreeView AnalyzerTreeView = App.ExportProvider.GetExportedValue<AnalyzerTreeView>();
 
 		public bool IsVisible(TextViewContext context)
 		{
@@ -60,17 +51,13 @@ namespace ICSharpCode.ILSpy.Analyzers
 				.All(node => IsValidReference(node.Member));
 		}
 
-		bool IsValidReference(object reference)
+		static bool IsValidReference(object reference)
 		{
-			return reference is IEntity && !(reference is IField f && f.IsConst);
+			return reference is IEntity and not IField { IsConst: true };
 		}
 
 		public void Execute(TextViewContext context)
 		{
-			if (AnalyzerTreeView is null)
-			{
-				return;
-			}
 			if (context.SelectedTreeNodes != null)
 			{
 				foreach (var node in context.SelectedTreeNodes.OfType<IMemberTreeNode>().ToArray())
@@ -86,25 +73,13 @@ namespace ICSharpCode.ILSpy.Analyzers
 
 		public override bool CanExecute(object parameter)
 		{
-			if (AnalyzerTreeView is null)
-			{
-				return false;
-			}
-
-			if (AnalyzerTreeView is { IsKeyboardFocusWithin: true })
-			{
-				return AnalyzerTreeView.SelectedItems.OfType<object>().All(n => n is IMemberTreeNode);
-			}
-
-			return MainWindow.Instance.SelectedNodes.All(n => n is IMemberTreeNode);
+			return AnalyzerTreeView.IsKeyboardFocusWithin
+				? AnalyzerTreeView.SelectedItems.OfType<object>().All(n => n is IMemberTreeNode)
+				: MainWindow.Instance.SelectedNodes.All(n => n is IMemberTreeNode);
 		}
 
 		public override void Execute(object parameter)
 		{
-			if (AnalyzerTreeView is null)
-			{
-				return;
-			}
 			if (AnalyzerTreeView.IsKeyboardFocusWithin)
 			{
 				foreach (var node in AnalyzerTreeView.SelectedItems.OfType<IMemberTreeNode>().ToArray())

ILSpy/Analyzers/AnalyzerTreeView.cs

@@ -29,6 +29,7 @@ using ICSharpCode.ILSpy.Docking;
 using ICSharpCode.ILSpy.ViewModels;
 using ICSharpCode.ILSpyX;
 using ICSharpCode.ILSpy.Controls.TreeView;
+using ICSharpCode.ILSpy.Util;
 using ICSharpCode.ILSpyX.TreeView;
 
 using TomsToolbox.Wpf.Composition.Mef;
@@ -48,25 +49,21 @@ namespace ICSharpCode.ILSpy.Analyzers
 		public AnalyzerTreeView()
 		{
 			this.ShowRoot = false;
-			this.Root = new AnalyzerRootNode { Language = MainWindow.Instance.CurrentLanguage };
 			this.BorderThickness = new Thickness(0);
 			ContextMenuProvider.Add(this);
-			MainWindow.Instance.CurrentAssemblyListChanged += MainWindow_Instance_CurrentAssemblyListChanged;
-			DockWorkspace.Instance.PropertyChanged += DockWorkspace_PropertyChanged;
+			MessageBus<CurrentAssemblyListChangedEventArgs>.Subscribers += (sender, e) => MainWindow_Instance_CurrentAssemblyListChanged(sender, e);
+			MessageBus<DockWorkspaceActiveTabPageChangedEventArgs>.Subscribers += DockWorkspace_ActiveTabPageChanged;
 			filterSettings = MainWindow.Instance.SessionSettings.FilterSettings;
 			filterSettings.PropertyChanged += FilterSettings_PropertyChanged;
 		}
 
-		private void DockWorkspace_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
+		private void DockWorkspace_ActiveTabPageChanged(object sender, EventArgs e)
 		{
-			switch (e.PropertyName)
-			{
-				case nameof(DockWorkspace.Instance.ActiveTabPage):
-					filterSettings.PropertyChanged -= FilterSettings_PropertyChanged;
-					filterSettings = DockWorkspace.Instance.ActiveTabPage.FilterSettings;
-					filterSettings.PropertyChanged += FilterSettings_PropertyChanged;
-					break;
-			}
+			this.Root ??= new AnalyzerRootNode { Language = MainWindow.Instance.CurrentLanguage };
+
+			filterSettings.PropertyChanged -= FilterSettings_PropertyChanged;
+			filterSettings = DockWorkspace.Instance.ActiveTabPage.FilterSettings;
+			filterSettings.PropertyChanged += FilterSettings_PropertyChanged;
 		}
 
 		private void FilterSettings_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)

ILSpy/Docking/DockWorkspace.cs

@@ -36,23 +36,23 @@ using AvalonDock.Layout.Serialization;
 
 using ICSharpCode.AvalonEdit.Highlighting;
 using ICSharpCode.ILSpy.TextView;
+using ICSharpCode.ILSpy.Util;
 using ICSharpCode.ILSpy.ViewModels;
 
+using TomsToolbox.Wpf;
+
 namespace ICSharpCode.ILSpy.Docking
 {
-	public class DockWorkspace : INotifyPropertyChanged, ILayoutUpdateStrategy
+	public class DockWorkspace : ObservableObject, ILayoutUpdateStrategy
 	{
 		private SessionSettings sessionSettings;
 
-		public event PropertyChangedEventHandler PropertyChanged;
-
-		public static DockWorkspace Instance { get; private set; }
+		public static readonly DockWorkspace Instance = new();
 
-		internal DockWorkspace(MainWindow parent)
+		private DockWorkspace()
 		{
-			Instance = this;
 			this.TabPages.CollectionChanged += Documents_CollectionChanged;
-			parent.CurrentAssemblyListChanged += MainWindow_Instance_CurrentAssemblyListChanged;
+			MessageBus<CurrentAssemblyListChangedEventArgs>.Subscribers += (sender, e) => MainWindow_Instance_CurrentAssemblyListChanged(sender, e);
 		}
 
 		private void MainWindow_Instance_CurrentAssemblyListChanged(object sender, NotifyCollectionChangedEventArgs e)
@@ -118,31 +118,31 @@ namespace ICSharpCode.ILSpy.Docking
 				tool.IsVisible = false;
 		}
 
-		private TabPageModel _activeTabPage = null;
+		private TabPageModel activeTabPage = null;
 		public TabPageModel ActiveTabPage {
 			get {
-				return _activeTabPage;
+				return activeTabPage;
 			}
 			set {
-				if (_activeTabPage != value)
+				if (!SetProperty(ref activeTabPage, value))
+				{
+					return;
+				}
+
+				var state = value.GetState();
+				if (state != null)
 				{
-					_activeTabPage = value;
-					var state = value.GetState();
-					if (state != null)
+					if (state.DecompiledNodes != null)
 					{
-						if (state.DecompiledNodes != null)
-						{
-							MainWindow.Instance.SelectNodes(state.DecompiledNodes,
-								inNewTabPage: false, setFocus: true, changingActiveTab: true);
-						}
-						else
-						{
-							MainWindow.Instance.NavigateTo(new RequestNavigateEventArgs(state.ViewedUri, null));
-						}
+						MainWindow.Instance.SelectNodes(state.DecompiledNodes,
+							inNewTabPage: false, setFocus: true, changingActiveTab: true);
+					}
+					else
+					{
+						MainWindow.Instance.NavigateTo(new(state.ViewedUri, null));
 					}
-
-					RaisePropertyChanged(nameof(ActiveTabPage));
 				}
+				MessageBus.Send(this, new DockWorkspaceActiveTabPageChangedEventArgs());
 			}
 		}
 
@@ -181,11 +181,6 @@ namespace ICSharpCode.ILSpy.Docking
 			}
 		}
 
-		protected void RaisePropertyChanged([CallerMemberName] string propertyName = null)
-		{
-			PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
-		}
-
 		public void ShowText(AvalonEditTextOutput textOutput)
 		{
 			ActiveTabPage.ShowTextView(textView => textView.ShowText(textOutput));

ILSpy/Docking/TabPageGuardConverter.cs

@@ -21,24 +21,20 @@ using System.Windows.Data;
 
 using ICSharpCode.ILSpy.ViewModels;
 
+using TomsToolbox.Wpf.Converters;
+
 namespace ICSharpCode.ILSpy.Docking
 {
-	public class ActiveTabPageConverter : IValueConverter
+	public class TabPageGuardConverter : ValueConverter
 	{
-		public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
+		protected override object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
 		{
-			if (value is TabPageModel)
-				return value;
-
-			return Binding.DoNothing;
+			return value is TabPageModel ? value : Binding.DoNothing;
 		}
 
-		public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
+		protected override object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
 		{
-			if (value is TabPageModel)
-				return value;
-
-			return Binding.DoNothing;
+			return value is TabPageModel ? value : Binding.DoNothing;
 		}
 	}
 }

ILSpy/MainWindow.xaml

@@ -26,8 +26,6 @@
 	d:DataContext="{d:DesignInstance local:MainWindowViewModel}"
 >
 	<Window.Resources>
-		<docking:ActiveTabPageConverter x:Key="ActiveTabPageConverter"/>
-
 		<tv:SharpTreeView x:Key="AssemblyTreeView"
 				AutomationProperties.Name="Assemblies and Classes"
 				SelectionChanged="TreeView_SelectionChanged"
@@ -82,6 +80,7 @@
 		<controls:CultureSelectionConverter x:Key="cultureSelectionConverter" />
 
 	</Window.Resources>
+
 	<b:Interaction.Behaviors>
 		<themes:WindowStyleManagerBehavior />
 	</b:Interaction.Behaviors>
@@ -109,12 +108,15 @@
 			Command="Search"
 			Executed="SearchCommandExecuted" />
 	</Window.CommandBindings>
+
 	<Window.InputBindings>
 		<KeyBinding Key="R" Modifiers="Control" Command="{x:Static local:ILSpyCommands.Analyze}" />
 	</Window.InputBindings>
+
 	<Window.TaskbarItemInfo>
 		<TaskbarItemInfo />
 	</Window.TaskbarItemInfo>
+
 	<DockPanel>
 		<!-- Main menu -->
 		<Menu DockPanel.Dock="Top" Name="mainMenu" Height="23" KeyboardNavigation.TabNavigation="None">
@@ -207,6 +209,7 @@
 			          ItemsSource="{Binding SelectedItem.LanguageVersions, ElementName=languageComboBox, UpdateSourceTrigger=PropertyChanged}"
 			          SelectedItem="{Binding Workspace.ActiveTabPage.FilterSettings.LanguageVersion, UpdateSourceTrigger=PropertyChanged}"/>
 		</ToolBar>
+		<!-- Update panel -->
 		<Border DockPanel.Dock="Top" BorderBrush="Black" BorderThickness="1" Name="updatePanel" Visibility="Collapsed">
 			<DockPanel KeyboardNavigation.TabNavigation="Contained">
 				<Button DockPanel.Dock="Right" Click="updatePanelCloseButtonClick" MinWidth="0">X</Button>
@@ -231,7 +234,7 @@
 									DataContext="{Binding Workspace}"
 									AnchorablesSource="{Binding ToolPanes}"
 									DocumentsSource="{Binding TabPages}"
-									ActiveContent="{Binding ActiveTabPage, Mode=TwoWay, Converter={StaticResource ActiveTabPageConverter}}"
+									ActiveContent="{Binding ActiveTabPage, Mode=TwoWay, Converter={docking:TabPageGuardConverter}}"
 									AllowMixedOrientation="True">
 
 			<avalondock:DockingManager.DocumentHeaderTemplate>

ILSpy/MainWindow.xaml.cs

@@ -42,7 +42,6 @@ using ICSharpCode.Decompiler.Documentation;
 using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.Decompiler.TypeSystem.Implementation;
-using ICSharpCode.ILSpy.Analyzers;
 using ICSharpCode.ILSpy.AppEnv;
 using ICSharpCode.ILSpy.Commands;
 using ICSharpCode.ILSpy.Docking;
@@ -57,6 +56,7 @@ using ICSharpCode.ILSpyX;
 using ICSharpCode.ILSpyX.FileLoaders;
 using ICSharpCode.ILSpyX.Settings;
 using ICSharpCode.ILSpy.Controls.TreeView;
+using ICSharpCode.ILSpy.Util;
 using ICSharpCode.ILSpyX.Extensions;
 
 using Microsoft.Win32;
@@ -130,7 +130,7 @@ namespace ICSharpCode.ILSpy
 			this.Icon = Images.ILSpyIcon;
 
 			this.DataContext = new MainWindowViewModel {
-				Workspace = new DockWorkspace(this),
+				Workspace = DockWorkspace.Instance,
 				SessionSettings = sessionSettings,
 				AssemblyListManager = AssemblyListManager
 			};
@@ -147,7 +147,7 @@ namespace ICSharpCode.ILSpy
 			sessionSettings.PropertyChanged += SessionSettings_PropertyChanged;
 			filterSettings = sessionSettings.FilterSettings;
 			filterSettings.PropertyChanged += filterSettings_PropertyChanged;
-			DockWorkspace.Instance.PropertyChanged += DockWorkspace_PropertyChanged;
+			MessageBus<DockWorkspaceActiveTabPageChangedEventArgs>.Subscribers += DockWorkspace_ActiveTabPageChanged;
 			InitMainMenu();
 			InitWindowMenu();
 			InitToolbar();
@@ -157,25 +157,20 @@ namespace ICSharpCode.ILSpy
 			this.Loaded += MainWindow_Loaded;
 		}
 
-		private void DockWorkspace_PropertyChanged(object sender, PropertyChangedEventArgs e)
+		private void DockWorkspace_ActiveTabPageChanged(object sender, EventArgs e)
 		{
-			switch (e.PropertyName)
-			{
-				case nameof(DockWorkspace.Instance.ActiveTabPage):
-					DockWorkspace dock = DockWorkspace.Instance;
-					filterSettings.PropertyChanged -= filterSettings_PropertyChanged;
-					filterSettings = dock.ActiveTabPage.FilterSettings;
-					filterSettings.PropertyChanged += filterSettings_PropertyChanged;
+			DockWorkspace dock = DockWorkspace.Instance;
+			filterSettings.PropertyChanged -= filterSettings_PropertyChanged;
+			filterSettings = dock.ActiveTabPage.FilterSettings;
+			filterSettings.PropertyChanged += filterSettings_PropertyChanged;
 
-					var windowMenuItem = mainMenu.Items.OfType<MenuItem>().First(m => (string)m.Tag == nameof(Properties.Resources._Window));
-					foreach (MenuItem menuItem in windowMenuItem.Items.OfType<MenuItem>())
-					{
-						if (menuItem.IsCheckable && menuItem.Tag is TabPageModel)
-						{
-							menuItem.IsChecked = menuItem.Tag == dock.ActiveTabPage;
-						}
-					}
-					break;
+			var windowMenuItem = mainMenu.Items.OfType<MenuItem>().First(m => (string)m.Tag == nameof(Properties.Resources._Window));
+			foreach (MenuItem menuItem in windowMenuItem.Items.OfType<MenuItem>())
+			{
+				if (menuItem.IsCheckable && menuItem.Tag is TabPageModel)
+				{
+					menuItem.IsChecked = menuItem.Tag == dock.ActiveTabPage;
+				}
 			}
 		}
 
@@ -359,7 +354,7 @@ namespace ICSharpCode.ILSpy
 		#endregion
 
 		#region Tool Pane extensibility
-		
+
 		private void InitToolPanes()
 		{
 			var toolPanes = App.ExportProvider.GetExportedValues<ToolPaneModel>("ToolPane");
@@ -632,8 +627,6 @@ namespace ICSharpCode.ILSpy
 			get { return assemblyList; }
 		}
 
-		public event NotifyCollectionChangedEventHandler CurrentAssemblyListChanged;
-
 		List<LoadedAssembly> commandLineLoadedAssemblies = new List<LoadedAssembly>();
 
 		internal async Task HandleSingleInstanceCommandLineArguments(string[] args)
@@ -1038,7 +1031,8 @@ namespace ICSharpCode.ILSpy
 					nd => nd.AncestorsAndSelf().OfType<AssemblyTreeNode>().Any(
 						a => oldAssemblies.Contains(a.LoadedAssembly))));
 			}
-			CurrentAssemblyListChanged?.Invoke(this, e);
+
+			MessageBus.Send(this, new CurrentAssemblyListChangedEventArgs(e));
 		}
 
 		void LoadInitialAssemblies()
@@ -1528,8 +1522,6 @@ namespace ICSharpCode.ILSpy
 		public Language CurrentLanguage => DockWorkspace.Instance.ActiveTabPage.FilterSettings.Language;
 		public LanguageVersion CurrentLanguageVersion => DockWorkspace.Instance.ActiveTabPage.FilterSettings.LanguageVersion;
 
-		public bool SupportsLanguageSwitching => DockWorkspace.Instance.ActiveTabPage.SupportsLanguageSwitching;
-
 		public event SelectionChangedEventHandler SelectionChanged;
 
 		public IEnumerable<ILSpyTreeNode> SelectedNodes {

ILSpy/Search/SearchPane.cs

@@ -35,6 +35,7 @@ using System.Windows.Threading;
 
 using ICSharpCode.ILSpy.AppEnv;
 using ICSharpCode.ILSpy.Docking;
+using ICSharpCode.ILSpy.Util;
 using ICSharpCode.ILSpy.ViewModels;
 using ICSharpCode.ILSpyX;
 using ICSharpCode.ILSpyX.Extensions;
@@ -82,7 +83,7 @@ namespace ICSharpCode.ILSpy.Search
 			searchModeComboBox.Items.Add(new { Image = Images.Namespace, Name = "Namespace" });
 
 			ContextMenuProvider.Add(listBox);
-			MainWindow.Instance.CurrentAssemblyListChanged += MainWindow_Instance_CurrentAssemblyListChanged;
+			MessageBus<CurrentAssemblyListChangedEventArgs>.Subscribers += (sender, e) => MainWindow_Instance_CurrentAssemblyListChanged(sender, e);
 			filterSettings = MainWindow.Instance.SessionSettings.FilterSettings;
 			CompositionTarget.Rendering += UpdateResults;
 

ILSpy/Util/MessageBus.cs

@@ -0,0 +1,55 @@
+using System;
+using System.Collections.Specialized;
+
+using TomsToolbox.Essentials;
+
+namespace ICSharpCode.ILSpy.Util
+{
+	public static class MessageBus
+	{
+		public static void Send<T>(object sender, T e)
+			where T : EventArgs
+		{
+			MessageBus<T>.Send(sender, e);
+		}
+	}
+
+	/// <summary>
+	/// Simple, minimalistic message bus.
+	/// </summary>
+	/// <typeparam name="T">The type of the message event arguments</typeparam>
+	public static class MessageBus<T>
+		where T : EventArgs
+	{
+		private static readonly WeakEventSource<T> Subscriptions = new();
+
+		public static event EventHandler<T> Subscribers {
+			add => Subscriptions.Subscribe(value);
+			remove => Subscriptions.Unsubscribe(value);
+		}
+
+		public static void Send(object sender, T e)
+		{
+			Subscriptions.Raise(sender, e);
+		}
+	}
+
+	public abstract class WrappedEventArgs<T> : EventArgs
+	{
+		private readonly T inner;
+
+		protected WrappedEventArgs(T inner)
+		{
+			this.inner = inner;
+		}
+
+		public static implicit operator T(WrappedEventArgs<T> outer)
+		{
+			return outer.inner;
+		}
+	}
+
+	public class CurrentAssemblyListChangedEventArgs(NotifyCollectionChangedEventArgs e) : WrappedEventArgs<NotifyCollectionChangedEventArgs>(e);
+
+	public class DockWorkspaceActiveTabPageChangedEventArgs : EventArgs;
+}

ILSpy/Views/DebugSteps.xaml.cs

@@ -8,6 +8,7 @@ using System.Windows.Input;
 using ICSharpCode.Decompiler.IL;
 using ICSharpCode.Decompiler.IL.Transforms;
 using ICSharpCode.ILSpy.Docking;
+using ICSharpCode.ILSpy.Util;
 using ICSharpCode.ILSpy.ViewModels;
 
 using TomsToolbox.Wpf.Composition.Mef;
@@ -35,7 +36,7 @@ namespace ICSharpCode.ILSpy
 			InitializeComponent();
 
 #if DEBUG
-			DockWorkspace.Instance.PropertyChanged += DockWorkspace_PropertyChanged;
+			MessageBus<DockWorkspaceActiveTabPageChangedEventArgs>.Subscribers += DockWorkspace_ActiveTabPageChanged;
 			filterSettings = DockWorkspace.Instance.ActiveTabPage.FilterSettings;
 			filterSettings.PropertyChanged += FilterSettings_PropertyChanged;
 			MainWindow.Instance.SelectionChanged += SelectionChanged;
@@ -50,16 +51,11 @@ namespace ICSharpCode.ILSpy
 #endif
 		}
 
-		private void DockWorkspace_PropertyChanged(object sender, PropertyChangedEventArgs e)
+		private void DockWorkspace_ActiveTabPageChanged(object sender, EventArgs e)
 		{
-			switch (e.PropertyName)
-			{
-				case nameof(DockWorkspace.Instance.ActiveTabPage):
-					filterSettings.PropertyChanged -= FilterSettings_PropertyChanged;
-					filterSettings = DockWorkspace.Instance.ActiveTabPage.FilterSettings;
-					filterSettings.PropertyChanged += FilterSettings_PropertyChanged;
-					break;
-			}
+			filterSettings.PropertyChanged -= FilterSettings_PropertyChanged;
+			filterSettings = DockWorkspace.Instance.ActiveTabPage.FilterSettings;
+			filterSettings.PropertyChanged += FilterSettings_PropertyChanged;
 		}
 
 		private void WritingOptions_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)