Refactor DocumentModel API

ILSpy.BamlDecompiler/BamlResourceEntryNode.cs

@@ -19,6 +19,7 @@ using ICSharpCode.ILSpy;
 using ICSharpCode.ILSpy.TextView;
 using ICSharpCode.ILSpy.TreeNodes;
 using ILSpy.BamlDecompiler.Baml;
+using ICSharpCode.ILSpy.ViewModels;
 
 namespace ILSpy.BamlDecompiler
 {
@@ -28,11 +29,12 @@ namespace ILSpy.BamlDecompiler
 		{
 		}
 		
-		public override bool View(DecompilerTextView textView)
+		public override bool View(TabPageModel tabPage)
 		{
 			IHighlightingDefinition highlighting = null;
 
-			textView.RunWithCancellation(
+			tabPage.SupportsLanguageSwitching = false;
+			tabPage.ShowTextView(textView => textView.RunWithCancellation(
 				token => Task.Factory.StartNew(
 					() => {
 						AvalonEditTextOutput output = new AvalonEditTextOutput();
@@ -45,7 +47,7 @@ namespace ILSpy.BamlDecompiler
 						return output;
 					}, token))
 				.Then(output => textView.ShowNode(output, this, highlighting))
-				.HandleExceptions();
+				.HandleExceptions());
 			return true;
 		}
 		

ILSpy/AboutPage.cs

@@ -32,6 +32,8 @@ using System.Xml.Linq;
 
 using ICSharpCode.AvalonEdit.Rendering;
 using ICSharpCode.Decompiler;
+using ICSharpCode.ILSpy.Docking;
+using ICSharpCode.ILSpy.ViewModels;
 using ICSharpCode.ILSpy.Properties;
 using ICSharpCode.ILSpy.TextView;
 using OSVersionHelper;
@@ -44,7 +46,7 @@ namespace ICSharpCode.ILSpy
 		public override void Execute(object parameter)
 		{
 			MainWindow.Instance.UnselectAll();
-			Display(Docking.DockWorkspace.Instance.GetTextView());
+			DockWorkspace.Instance.ActiveTabPage.ShowTextView(Display);
 		}
 		
 		static readonly Uri UpdateUrl = new Uri("https://ilspy.net/updates.xml");

ILSpy/Commands/DecompileInNewViewCommand.cs

@@ -70,8 +70,8 @@ namespace ICSharpCode.ILSpy.Commands
 				return;
 
 			var title = string.Join(", ", nodes.Select(x => x.ToString()));
-			DockWorkspace.Instance.Documents.Add(new ViewModels.DecompiledDocumentModel(title, title) { Language = MainWindow.Instance.CurrentLanguage, LanguageVersion = MainWindow.Instance.CurrentLanguageVersion });
-			DockWorkspace.Instance.ActiveDocument = DockWorkspace.Instance.Documents.Last();
+			DockWorkspace.Instance.TabPages.Add(new ViewModels.TabPageModel() { Language = MainWindow.Instance.CurrentLanguage, LanguageVersion = MainWindow.Instance.CurrentLanguageVersion });
+			DockWorkspace.Instance.ActiveTabPage = DockWorkspace.Instance.TabPages.Last();
 			MainWindow.Instance.SelectNodes(nodes);
 			MainWindow.Instance.Dispatcher.BeginInvoke(DispatcherPriority.Background, (Action)MainWindow.Instance.RefreshDecompiledView);
 		}

ILSpy/Commands/SaveCodeContextMenuEntry.cs

@@ -24,6 +24,7 @@ using System.Windows;
 using System.Windows.Input;
 using ICSharpCode.ILSpy.Properties;
 using ICSharpCode.ILSpy.TreeNodes;
+using ICSharpCode.ILSpy.ViewModels;
 using ICSharpCode.TreeView;
 using Microsoft.Win32;
 
@@ -55,28 +56,30 @@ namespace ICSharpCode.ILSpy.TextView
 		public static void Execute(IReadOnlyList<SharpTreeNode> selectedNodes)
 		{
 			var currentLanguage = MainWindow.Instance.CurrentLanguage;
-			var textView = Docking.DockWorkspace.Instance.GetTextView();
-			if (selectedNodes.Count == 1 && selectedNodes[0] is ILSpyTreeNode singleSelection) {
-				// if there's only one treenode selected
-				// we will invoke the custom Save logic
-				if (singleSelection.Save(textView))
-					return;
-			} else if (selectedNodes.Count > 1 && selectedNodes.All(n => n is AssemblyTreeNode)) {
-				var selectedPath = SelectSolutionFile();
+			var tabPage = Docking.DockWorkspace.Instance.ActiveTabPage;
+			tabPage.ShowTextView(textView => {
+				if (selectedNodes.Count == 1 && selectedNodes[0] is ILSpyTreeNode singleSelection) {
+					// if there's only one treenode selected
+					// we will invoke the custom Save logic
+					if (singleSelection.Save(tabPage))
+						return;
+				} else if (selectedNodes.Count > 1 && selectedNodes.All(n => n is AssemblyTreeNode)) {
+					var selectedPath = SelectSolutionFile();
 
-				if (!string.IsNullOrEmpty(selectedPath)) {
-					var assemblies = selectedNodes.OfType<AssemblyTreeNode>()
-						.Select(n => n.LoadedAssembly)
-						.Where(a => !a.HasLoadError).ToArray();
-					SolutionWriter.CreateSolution(textView, selectedPath, currentLanguage, assemblies);
+					if (!string.IsNullOrEmpty(selectedPath)) {
+						var assemblies = selectedNodes.OfType<AssemblyTreeNode>()
+							.Select(n => n.LoadedAssembly)
+							.Where(a => !a.HasLoadError).ToArray();
+						SolutionWriter.CreateSolution(textView, selectedPath, currentLanguage, assemblies);
+					}
+					return;
 				}
-				return;
-			}
 
-			// Fallback: if nobody was able to handle the request, use default behavior.
-			// try to save all nodes to disk.
-			var options = new DecompilationOptions() { FullDecompilation = true };
-			textView.SaveToDisk(currentLanguage, selectedNodes.OfType<ILSpyTreeNode>(), options);
+				// Fallback: if nobody was able to handle the request, use default behavior.
+				// try to save all nodes to disk.
+				var options = new DecompilationOptions() { FullDecompilation = true };
+				textView.SaveToDisk(currentLanguage, selectedNodes.OfType<ILSpyTreeNode>(), options);
+			});
 		}
 
 		/// <summary>

ILSpy/DebugSteps.xaml.cs

@@ -123,13 +123,13 @@ namespace ICSharpCode.ILSpy
 		{
 			lastSelectedStep = step;
 			var window = MainWindow.Instance;
-			var state = DockWorkspace.Instance.GetState();
-			DockWorkspace.Instance.GetTextView().DecompileAsync(window.CurrentLanguage, window.SelectedNodes,
+			var state = DockWorkspace.Instance.ActiveTabPage.GetState();
+			DockWorkspace.Instance.ActiveTabPage.ShowTextViewAsync(textView => textView.DecompileAsync(window.CurrentLanguage, window.SelectedNodes,
 				new DecompilationOptions(window.CurrentLanguageVersion) {
 					StepLimit = step,
 					IsDebug = isDebug,
-					TextViewState = state
-				});
+					TextViewState = state as TextView.DecompilerTextViewState
+				}));
 		}
 
 		private void tree_KeyDown(object sender, KeyEventArgs e)

ILSpy/Docking/ActiveTabPageConverter.cs

@@ -22,11 +22,11 @@ using ICSharpCode.ILSpy.ViewModels;
 
 namespace ICSharpCode.ILSpy.Docking
 {
-	public class ActiveDocumentConverter : IValueConverter
+	public class ActiveTabPageConverter : IValueConverter
 	{
 		public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
 		{
-			if (value is DocumentModel)
+			if (value is TabPageModel)
 				return value;
 
 			return Binding.DoNothing;
@@ -34,7 +34,7 @@ namespace ICSharpCode.ILSpy.Docking
 
 		public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
 		{
-			if (value is DocumentModel)
+			if (value is TabPageModel)
 				return value;
 
 			return Binding.DoNothing;

ILSpy/Docking/CloseAllDocumentsCommand.cs

@@ -12,7 +12,7 @@ namespace ICSharpCode.ILSpy.Docking
 	{
 		public override void Execute(object parameter)
 		{
-			DockWorkspace.Instance.CloseAllDocuments();
+			DockWorkspace.Instance.CloseAllTabs();
 		}
 	}
 

ILSpy/Docking/DockWorkspace.cs

@@ -44,19 +44,19 @@ namespace ICSharpCode.ILSpy.Docking
 
 		private DockWorkspace()
 		{
-			this.Documents.CollectionChanged += Documents_CollectionChanged;
+			this.TabPages.CollectionChanged += Documents_CollectionChanged;
 		}
 
 		private void Documents_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
 		{
-			var collection = (PaneCollection<DocumentModel>)sender;
+			var collection = (PaneCollection<TabPageModel>)sender;
 			bool canClose = collection.Count > 1;
 			foreach (var item in collection) {
 				item.IsCloseable = canClose;
 			}
 		}
 
-		public PaneCollection<DocumentModel> Documents { get; } = new PaneCollection<DocumentModel>();
+		public PaneCollection<TabPageModel> TabPages { get; } = new PaneCollection<TabPageModel>();
 
 		private ToolPaneModel[] toolPanes;
 		public IEnumerable<ToolPaneModel> ToolPanes {
@@ -77,30 +77,26 @@ namespace ICSharpCode.ILSpy.Docking
 
 		public void Remove(PaneModel model)
 		{
-			if (model is DocumentModel document)
-				Documents.Remove(document);
+			if (model is TabPageModel document)
+				TabPages.Remove(document);
 			if (model is ToolPaneModel tool)
 				tool.IsVisible = false;
 		}
 
-		private DocumentModel _activeDocument = null;
-		public DocumentModel ActiveDocument {
+		private TabPageModel _activeTabPage = null;
+		public TabPageModel ActiveTabPage {
 			get {
-				return _activeDocument;
+				return _activeTabPage;
 			}
 			set {
-				if (_activeDocument != value) {
-					_activeDocument = value;
-					if (value is DecompiledDocumentModel ddm) {
-						this.sessionSettings.FilterSettings.Language = ddm.Language;
-						this.sessionSettings.FilterSettings.LanguageVersion = ddm.LanguageVersion;
-						if (ddm.TextView is DecompilerTextView view) {
-							var state = view.GetState();
-							if (state != null)
-								MainWindow.Instance.SelectNodes(state.DecompiledNodes);
-						}
-					}
-					RaisePropertyChanged(nameof(ActiveDocument));
+				if (_activeTabPage != value) {
+					_activeTabPage = value;
+					this.sessionSettings.FilterSettings.Language = value.Language;
+					this.sessionSettings.FilterSettings.LanguageVersion = value.LanguageVersion;
+					var state = value.GetState();
+					if (state != null)
+						MainWindow.Instance.SelectNodes(state.DecompiledNodes);
+					RaisePropertyChanged(nameof(ActiveTabPage));
 				}
 			}
 		}
@@ -158,27 +154,17 @@ namespace ICSharpCode.ILSpy.Docking
 
 		public void ShowText(AvalonEditTextOutput textOutput)
 		{
-			GetTextView().ShowText(textOutput);
-		}
-
-		public DecompilerTextView GetTextView()
-		{
-			return ((DecompiledDocumentModel)ActiveDocument).TextView;
-		}
-
-		public DecompilerTextViewState GetState()
-		{
-			return GetTextView()?.GetState();
+			ActiveTabPage.ShowTextView(textView => textView.ShowText(textOutput));
 		}
 
 		public Task<T> RunWithCancellation<T>(Func<CancellationToken, Task<T>> taskCreation)
 		{
-			return GetTextView().RunWithCancellation(taskCreation);
+			return ActiveTabPage.ShowTextViewAsync(textView => textView.RunWithCancellation(taskCreation));
 		}
 
 		internal void ShowNodes(AvalonEditTextOutput output, TreeNodes.ILSpyTreeNode[] nodes, IHighlightingDefinition highlighting)
 		{
-			GetTextView().ShowNodes(output, nodes, highlighting);
+			ActiveTabPage.ShowTextView(textView => textView.ShowNodes(output, nodes, highlighting));
 		}
 
 		internal void LoadSettings(SessionSettings sessionSettings)
@@ -189,19 +175,17 @@ namespace ICSharpCode.ILSpy.Docking
 
 		private void FilterSettings_PropertyChanged(object sender, PropertyChangedEventArgs e)
 		{
-			if (ActiveDocument is DecompiledDocumentModel ddm) {
-				if (e.PropertyName == "Language" || e.PropertyName == "LanguageVersion") {
-					ddm.Language = sessionSettings.FilterSettings.Language;
-					ddm.LanguageVersion = sessionSettings.FilterSettings.LanguageVersion;
-				}
+			if (e.PropertyName == "Language" || e.PropertyName == "LanguageVersion") {
+				ActiveTabPage.Language = sessionSettings.FilterSettings.Language;
+				ActiveTabPage.LanguageVersion = sessionSettings.FilterSettings.LanguageVersion;
 			}
 		}
 
-		internal void CloseAllDocuments()
+		internal void CloseAllTabs()
 		{
-			foreach (var doc in Documents.ToArray()) {
+			foreach (var doc in TabPages.ToArray()) {
 				if (doc.IsCloseable)
-					Documents.Remove(doc);
+					TabPages.Remove(doc);
 			}
 		}
 
@@ -210,7 +194,7 @@ namespace ICSharpCode.ILSpy.Docking
 			foreach (var pane in ToolPanes) {
 				pane.IsVisible = false;
 			}
-			CloseAllDocuments();
+			CloseAllTabs();
 			sessionSettings.DockLayout.Reset();
 			InitializeLayout(MainWindow.Instance.DockManager);
 			MainWindow.Instance.Dispatcher.BeginInvoke(DispatcherPriority.Background, (Action)MainWindow.Instance.RefreshDecompiledView);

ILSpy/Docking/PanePosition.cs

@@ -1,29 +0,0 @@
-// Copyright (c) 2019 AlphaSierraPapa for the SharpDevelop Team
-// 
-// Permission is hereby granted, free of charge, to any person obtaining a copy of this
-// software and associated documentation files (the "Software"), to deal in the Software
-// without restriction, including without limitation the rights to use, copy, modify, merge,
-// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
-// to whom the Software is furnished to do so, subject to the following conditions:
-// 
-// The above copyright notice and this permission notice shall be included in all copies or
-// substantial portions of the Software.
-// 
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
-// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
-// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
-// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
-// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
-// DEALINGS IN THE SOFTWARE.
-
-namespace ICSharpCode.ILSpy
-{
-	public enum PanePosition
-	{
-		Top,
-		Bottom,
-		Left,
-		Right,
-		Document
-	}
-}

ILSpy/Docking/PaneStyleSelector.cs

@@ -25,12 +25,12 @@ namespace ICSharpCode.ILSpy.Docking
 	{
 		public Style ToolPaneStyle { get; set; }
 
-		public Style DocumentStyle { get; set; }
+		public Style TabPageStyle { get; set; }
 
 		public override Style SelectStyle(object item, DependencyObject container)
 		{
-			if (item is DocumentModel)
-				return DocumentStyle;
+			if (item is TabPageModel)
+				return TabPageStyle;
 
 			if (item is ToolPaneModel)
 				return ToolPaneStyle;

ILSpy/ILSpy.csproj

@@ -141,11 +141,11 @@
     <Compile Include="DebugSteps.xaml.cs">
       <DependentUpon>DebugSteps.xaml</DependentUpon>
     </Compile>
-    <Compile Include="Docking\ActiveDocumentConverter.cs" />
+    <Compile Include="Docking\ActiveTabPageConverter.cs" />
     <Compile Include="Docking\CloseAllDocumentsCommand.cs" />
     <Compile Include="ViewModels\AssemblyListPaneModel.cs" />
     <Compile Include="Docking\DockLayoutSettings.cs" />
-    <Compile Include="ViewModels\DocumentModel.cs" />
+    <Compile Include="ViewModels\TabPageModel.cs" />
     <Compile Include="Docking\PaneCollection.cs" />
     <Compile Include="ViewModels\PaneModel.cs" />
     <Compile Include="Docking\PaneStyleSelector.cs" />
@@ -184,7 +184,6 @@
       <Generator>MSBuild:Compile</Generator>
     </Compile>
     <Compile Include="Options\DecompilerSettingsPanel.xaml.cs" />
-    <Compile Include="Docking\PanePosition.cs" />
     <Compile Include="Properties\Resources.Designer.cs">
       <DesignTime>True</DesignTime>
       <AutoGen>True</AutoGen>

ILSpy/MainWindow.xaml

@@ -23,7 +23,7 @@
 >
 	<Window.Resources>
 		<controls:BoolToVisibilityConverter x:Key="BooleanToVisibilityConverter" />
-		<docking:ActiveDocumentConverter x:Key="ActiveDocumentConverter"/>
+		<docking:ActiveTabPageConverter x:Key="ActiveTabPageConverter"/>
 
 		<tv:SharpTreeView x:Key="TreeView"
 				AutomationProperties.Name="Assemblies and Classes"
@@ -55,8 +55,8 @@
 			<ContentControl Content="{StaticResource AnalyzerTreeView}" />
 		</DataTemplate>
 
-		<DataTemplate x:Key="DecompilerTextViewTemplate">
-			<textview:DecompilerTextView DataContext="{Binding}" />
+		<DataTemplate x:Key="DefaultContentTemplate">
+			<ContentPresenter Content="{Binding Content}" />
 		</DataTemplate>
 	</Window.Resources>
 
@@ -132,10 +132,12 @@
 			</CheckBox>
 			<Separator />
 			<ComboBox Name="languageComboBox" DisplayMemberPath="Name" Width="100" MaxDropDownHeight="Auto"
+					  IsEnabled="{Binding ActiveTabPage.SupportsLanguageSwitching, Source={x:Static docking:DockWorkspace.Instance}}"
 			          ItemsSource="{x:Static local:Languages.AllLanguages}" ToolTip="{x:Static properties:Resources.SelectLanguageDropdownTooltip}"
 			          SelectedItem="{Binding SessionSettings.FilterSettings.Language}"/>
 			<ComboBox Name="languageVersionComboBox" DisplayMemberPath="DisplayName" Width="120" MaxDropDownHeight="Auto" ToolTip="{x:Static properties:Resources.SelectVersionDropdownTooltip}"
 			          Visibility="{Binding SelectedItem.HasLanguageVersions, ElementName=languageComboBox, Converter={StaticResource BooleanToVisibilityConverter}}"
+					  IsEnabled="{Binding ActiveTabPage.SupportsLanguageSwitching, Source={x:Static docking:DockWorkspace.Instance}}"
 			          ItemsSource="{Binding SelectedItem.LanguageVersions, ElementName=languageComboBox, UpdateSourceTrigger=PropertyChanged}"
 			          SelectedItem="{Binding SessionSettings.FilterSettings.LanguageVersion, UpdateSourceTrigger=PropertyChanged}"/>
 		</ToolBar>
@@ -162,8 +164,8 @@
 		<avalondock:DockingManager x:Name="DockManager"
 									DataContext="{Binding Workspace}"
 									AnchorablesSource="{Binding ToolPanes}" 
-									DocumentsSource="{Binding Documents}"
-									ActiveContent="{Binding ActiveDocument, Mode=TwoWay, Converter={StaticResource ActiveDocumentConverter}}"
+									DocumentsSource="{Binding TabPages}"
+									ActiveContent="{Binding ActiveTabPage, Mode=TwoWay, Converter={StaticResource ActiveTabPageConverter}}"
 									AllowMixedOrientation="True">
 
 			<avalondock:DockingManager.DocumentHeaderTemplate>
@@ -184,7 +186,7 @@
 						<docking:TemplateMapping Type="{x:Type viewmodels:SearchPaneModel}" Template="{StaticResource SearchPaneTemplate}" />
 						<docking:TemplateMapping Type="{x:Type viewmodels:DebugStepsPaneModel}" Template="{StaticResource DebugStepsPaneTemplate}" />
 						<docking:TemplateMapping Type="{x:Type viewmodels:AnalyzerPaneModel}" Template="{StaticResource AnalyzerPaneTemplate}" />
-						<docking:TemplateMapping Type="{x:Type viewmodels:DecompiledDocumentModel}" Template="{StaticResource DecompilerTextViewTemplate}" />
+						<docking:TemplateMapping Type="{x:Type viewmodels:TabPageModel}" Template="{StaticResource DefaultContentTemplate}" />
 					</docking:PaneTemplateSelector.Mappings>
 				</docking:PaneTemplateSelector>
 			</avalondock:DockingManager.LayoutItemTemplateSelector>
@@ -203,7 +205,7 @@
 							<Setter Property="CanClose" Value="{Binding Model.IsCloseable}" />
 						</Style>
 					</docking:PaneStyleSelector.ToolPaneStyle>
-					<docking:PaneStyleSelector.DocumentStyle>
+					<docking:PaneStyleSelector.TabPageStyle>
 						<Style TargetType="{x:Type avalondock:LayoutItem}">
 							<Setter Property="Title" Value="{Binding Model.Title}"/>
 							<Setter Property="Visibility" Value="{Binding Model.IsVisible, Mode=TwoWay, Converter={StaticResource BooleanToVisibilityConverter}, ConverterParameter={x:Static Visibility.Hidden}}"/>
@@ -213,7 +215,7 @@
 							<Setter Property="CloseCommand" Value="{Binding Model.CloseCommand}" />
 							<Setter Property="CanClose" Value="{Binding Model.IsCloseable, Mode=TwoWay}" />
 						</Style>
-					</docking:PaneStyleSelector.DocumentStyle>
+					</docking:PaneStyleSelector.TabPageStyle>
 				</docking:PaneStyleSelector>
 			</avalondock:DockingManager.LayoutItemContainerStyleSelector>
 		</avalondock:DockingManager>

ILSpy/MainWindow.xaml.cs

@@ -392,7 +392,7 @@ namespace ICSharpCode.ILSpy
 						// only if not showing the about page, perform the update check:
 						await ShowMessageIfUpdatesAvailableAsync(spySettings);
 					} else {
-						AboutPage.Display(DockWorkspace.Instance.GetTextView());
+						DockWorkspace.Instance.ActiveTabPage.ShowTextView(AboutPage.Display);
 					}
 				}
 			}
@@ -453,11 +453,11 @@ namespace ICSharpCode.ILSpy
 
 		void MainWindow_Loaded(object sender, RoutedEventArgs e)
 		{
-			DockWorkspace.Instance.Documents.Add(new DecompiledDocumentModel() {
+			DockWorkspace.Instance.TabPages.Add(new TabPageModel() {
 				Language = CurrentLanguage,
 				LanguageVersion = CurrentLanguageVersion
 			});
-			DockWorkspace.Instance.ActiveDocument = DockWorkspace.Instance.Documents.First();
+			DockWorkspace.Instance.ActiveTabPage = DockWorkspace.Instance.TabPages.First();
 
 			ILSpySettings spySettings = this.spySettingsForMainWindow_Loaded;
 			this.spySettingsForMainWindow_Loaded = null;
@@ -930,7 +930,7 @@ namespace ICSharpCode.ILSpy
 		Task decompilationTask;
 		bool ignoreDecompilationRequests;
 
-		void DecompileSelectedNodes(DecompilerTextViewState state = null, bool recordHistory = true)
+		void DecompileSelectedNodes(DecompilerTextViewState newState = null, bool recordHistory = true)
 		{
 			if (ignoreDecompilationRequests)
 				return;
@@ -939,18 +939,20 @@ namespace ICSharpCode.ILSpy
 				return;
 
 			if (recordHistory) {
-				var dtState = DockWorkspace.Instance.GetState();
-				if (dtState != null)
-					history.UpdateCurrent(new NavigationState(dtState));
+				var currentState = DockWorkspace.Instance.ActiveTabPage.GetState();
+				if (currentState != null)
+					history.UpdateCurrent(new NavigationState(currentState));
 				history.Record(new NavigationState(treeView.SelectedItems.OfType<SharpTreeNode>()));
 			}
 
+			DockWorkspace.Instance.ActiveTabPage.SupportsLanguageSwitching = true;
+
 			if (treeView.SelectedItems.Count == 1) {
 				ILSpyTreeNode node = treeView.SelectedItem as ILSpyTreeNode;
-				if (node != null && node.View(DockWorkspace.Instance.GetTextView()))
+				if (node != null && node.View(DockWorkspace.Instance.ActiveTabPage))
 					return;
 			}
-			decompilationTask = DockWorkspace.Instance.GetTextView().DecompileAsync(this.CurrentLanguage, this.SelectedNodes, new DecompilationOptions() { TextViewState = state });
+			decompilationTask = DockWorkspace.Instance.ActiveTabPage.ShowTextViewAsync(textView => textView.DecompileAsync(this.CurrentLanguage, this.SelectedNodes, new DecompilationOptions() { TextViewState = newState }));
 		}
 
 		void SaveCommandCanExecute(object sender, CanExecuteRoutedEventArgs e)
@@ -1017,9 +1019,9 @@ namespace ICSharpCode.ILSpy
 
 		void NavigateHistory(bool forward)
 		{
-			var dtState = DockWorkspace.Instance.GetState();
-			if (dtState != null)
-				history.UpdateCurrent(new NavigationState(dtState));
+			var state = DockWorkspace.Instance.ActiveTabPage.GetState();
+			if (state != null)
+				history.UpdateCurrent(new NavigationState(state));
 			var newState = forward ? history.GoForward() : history.GoBack();
 
 			ignoreDecompilationRequests = true;
@@ -1030,7 +1032,7 @@ namespace ICSharpCode.ILSpy
 			if (newState.TreeNodes.Any())
 				treeView.FocusNode(newState.TreeNodes.First());
 			ignoreDecompilationRequests = false;
-			DecompileSelectedNodes(newState.ViewState, false);
+			DecompileSelectedNodes(newState.ViewState as DecompilerTextViewState, false);
 		}
 
 		#endregion

ILSpy/Metadata/CoffHeaderTreeNode.cs

@@ -25,6 +25,7 @@ using ICSharpCode.Decompiler;
 using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.ILSpy.TextView;
 using ICSharpCode.ILSpy.TreeNodes;
+using ICSharpCode.ILSpy.ViewModels;
 
 namespace ICSharpCode.ILSpy.Metadata
 {
@@ -41,8 +42,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			var dataGrid = new DataGrid {
 				Columns = {
 					new DataGridTextColumn { IsReadOnly = true, Header = "Member", Binding = new Binding("Member") },
@@ -71,7 +73,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			dataGrid.ItemsSource = entries;
 
-			textView.ShowContent(new[] { this }, dataGrid);
+			tabPage.Content = dataGrid;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/AssemblyRefTableTreeNode.cs

@@ -41,8 +41,11 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.Title = Text.ToString();
+			tabPage.SupportsLanguageSwitching = false;
+
 			ListView view = Helpers.CreateListView("AssemblyRefView");
 
 			var metadata = module.Metadata;
@@ -55,7 +58,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/AssemblyTableTreeNode.cs

@@ -48,8 +48,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("AssemblyView");
 
 			var metadata = module.Metadata;
@@ -60,7 +61,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/ConstantTableTreeNode.cs

@@ -26,6 +26,7 @@ using ICSharpCode.Decompiler.IL;
 using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.ILSpy.TextView;
 using ICSharpCode.ILSpy.TreeNodes;
+using ICSharpCode.ILSpy.ViewModels;
 
 namespace ICSharpCode.ILSpy.Metadata
 {
@@ -42,20 +43,21 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("ConstantsView");
 			var metadata = module.Metadata;
 
 			var list = new List<ConstantEntry>();
 
-			for (int row = 1; row <= module.Metadata.GetTableRowCount(TableIndex.Constant); row++) {
+			for (int row = 1; row <= metadata.GetTableRowCount(TableIndex.Constant); row++) {
 				list.Add(new ConstantEntry(module, MetadataTokens.ConstantHandle(row)));
 			}
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/CustomAttributeTableTreeNode.cs

@@ -46,8 +46,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("CustomAttributesView");
 			var metadata = module.Metadata;
 
@@ -59,7 +60,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/DeclSecurityTableTreeNode.cs

@@ -46,8 +46,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("DeclSecurityAttrsView");
 			var metadata = module.Metadata;
 
@@ -59,7 +60,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/EventTableTreeNode.cs

@@ -47,8 +47,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("EventDefsView");
 			var metadata = module.Metadata;
 
@@ -59,7 +60,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/ExportedTypeTableTreeNode.cs

@@ -48,8 +48,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("ExportedTypesView");
 
 			var metadata = module.Metadata;
@@ -62,7 +63,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/FieldLayoutTableTreeNode.cs

@@ -47,8 +47,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("FieldLayoutsView");
 			var metadata = module.Metadata;
 
@@ -62,7 +63,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/FieldTableTreeNode.cs

@@ -47,8 +47,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("FieldDefsView");
 			var metadata = module.Metadata;
 
@@ -59,7 +60,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/FileTableTreeNode.cs

@@ -46,8 +46,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("FilesView");
 			var metadata = module.Metadata;
 
@@ -59,7 +60,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/GenericParamConstraintTableTreeNode.cs

@@ -50,8 +50,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("GenericParamConstraintsView");
 			var metadata = module.Metadata;
 			
@@ -62,7 +63,7 @@ namespace ICSharpCode.ILSpy.Metadata
 			}
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/GenericParamTableTreeNode.cs

@@ -50,8 +50,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("GenericParamsView");
 			var metadata = module.Metadata;
 			
@@ -62,7 +63,7 @@ namespace ICSharpCode.ILSpy.Metadata
 			}
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/ManifestResourceTableTreeNode.cs

@@ -46,8 +46,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("ManifestResourcesView");
 			var metadata = module.Metadata;
 
@@ -59,7 +60,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/MemberRefTableTreeNode.cs

@@ -47,8 +47,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("MemberRefsView");
 			var metadata = module.Metadata;
 
@@ -59,7 +60,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/MethodImplTableTreeNode.cs

@@ -48,8 +48,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("MethodImplView");
 			var metadata = module.Metadata;
 
@@ -61,7 +62,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/MethodSemanticsTableTreeNode.cs

@@ -48,8 +48,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("MethodSemanticsView");
 			var metadata = module.Metadata;
 
@@ -60,7 +61,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/MethodSpecTableTreeNode.cs

@@ -50,8 +50,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("MethodSpecsView");
 			var metadata = module.Metadata;
 			
@@ -62,7 +63,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 			
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/MethodTableTreeNode.cs

@@ -47,8 +47,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("MethodDefsView");
 			var metadata = module.Metadata;
 
@@ -59,7 +60,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/ModuleRefTableTreeNode.cs

@@ -48,8 +48,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("ModuleRefsView");
 			var metadata = module.Metadata;
 			
@@ -60,7 +61,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 			
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/ModuleTableTreeNode.cs

@@ -48,8 +48,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("ModulesView");
 			var metadata = module.Metadata;
 			
@@ -59,7 +60,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 			
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/ParamTableTreeNode.cs

@@ -50,8 +50,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("ParamsView");
 			var metadata = module.Metadata;
 			
@@ -63,7 +64,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 			
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/PropertyTableTreeNode.cs

@@ -47,8 +47,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("PropertyDefsView");
 			var metadata = module.Metadata;
 
@@ -59,7 +60,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/StandAloneSigTableTreeNode.cs

@@ -46,8 +46,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("StandAloneSigsView");
 			var metadata = module.Metadata;
 
@@ -59,7 +60,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/TypeDefTableTreeNode.cs

@@ -51,8 +51,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("TypeDefsView");
 			var metadata = module.Metadata;
 
@@ -63,7 +64,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/TypeRefTableTreeNode.cs

@@ -49,8 +49,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("TypeRefsView");
 
 			var metadata = module.Metadata;
@@ -62,7 +63,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 			
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/CorTables/TypeSpecTableTreeNode.cs

@@ -50,8 +50,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			ListView view = Helpers.CreateListView("TypeSpecsView");
 			var metadata = module.Metadata;
 			
@@ -62,7 +63,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = list;
 			
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/DataDirectoriesTreeNode.cs

@@ -39,8 +39,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			var dataGrid = new DataGrid {
 				Columns = {
 					new DataGridTextColumn { IsReadOnly = true, Header = "Name", Binding = new Binding("Name") },
@@ -76,7 +77,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			dataGrid.ItemsSource = entries;
 
-			textView.ShowContent(new[] { this }, dataGrid);
+			tabPage.Content = dataGrid;
 			return true;
 		}
 

ILSpy/Metadata/DosHeaderTreeNode.cs

@@ -21,8 +21,8 @@ using System.Windows.Controls;
 using System.Windows.Data;
 using ICSharpCode.Decompiler;
 using ICSharpCode.Decompiler.Metadata;
-using ICSharpCode.ILSpy.TextView;
 using ICSharpCode.ILSpy.TreeNodes;
+using ICSharpCode.ILSpy.ViewModels;
 
 namespace ICSharpCode.ILSpy.Metadata
 {
@@ -39,8 +39,9 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(TabPageModel tabPage)
 		{
+			tabPage.SupportsLanguageSwitching = false;
 			var view = Helpers.CreateListView("EntryView");
 			var reader = module.Reader.GetEntireImage().GetReader(0, 64);
 
@@ -80,7 +81,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			view.ItemsSource = entries;
 
-			textView.ShowContent(new[] { this }, view);
+			tabPage.Content = view;
 			return true;
 		}
 

ILSpy/Metadata/MetadataTreeNode.cs

@@ -28,6 +28,7 @@ using System.Windows.Data;
 using ICSharpCode.Decompiler;
 using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.ILSpy.TreeNodes;
+using ICSharpCode.ILSpy.ViewModels;
 
 namespace ICSharpCode.ILSpy.Metadata
 {
@@ -47,6 +48,12 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Library;
 
+		public override bool View(TabPageModel tabPage)
+		{
+			tabPage.SupportsLanguageSwitching = false;
+			return false;
+		}
+
 		public override void Decompile(Language language, ITextOutput output, DecompilationOptions options)
 		{
 			language.WriteCommentLine(output, "Metadata");

ILSpy/Metadata/OptionalHeaderTreeNode.cs

@@ -41,7 +41,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 		public override object Icon => Images.Literal;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(ViewModels.TabPageModel tabPage)
 		{
 			var dataGrid = new DataGrid {
 				Columns = {
@@ -95,7 +95,7 @@ namespace ICSharpCode.ILSpy.Metadata
 
 			dataGrid.ItemsSource = entries;
 
-			textView.ShowContent(new[] { this }, dataGrid);
+			tabPage.Content = dataGrid;
 			return true;
 		}
 

ILSpy/NavigationState.cs

@@ -28,9 +28,9 @@ namespace ICSharpCode.ILSpy
 		private readonly HashSet<SharpTreeNode> treeNodes;
 
 		public IEnumerable<SharpTreeNode> TreeNodes { get { return treeNodes; } }
-		public DecompilerTextViewState ViewState { get; private set; }
+		public ViewState ViewState { get; private set; }
 
-		public NavigationState(DecompilerTextViewState viewState)
+		public NavigationState(ViewState viewState)
 		{
 			this.treeNodes = new HashSet<SharpTreeNode>(viewState.DecompiledNodes);
 			ViewState = viewState;

ILSpy/TextView/DecompilerTextView.cs

@@ -559,9 +559,6 @@ namespace ICSharpCode.ILSpy.TextView
 		/// </summary>
 		public void ShowNodes(AvalonEditTextOutput textOutput, ILSpyTreeNode[] nodes, IHighlightingDefinition highlighting = null)
 		{
-			textEditor.Visibility = Visibility.Visible;
-			dynamicContent.Visibility = Visibility.Hidden;
-			dynamicContent.Content = null;
 			// Cancel the decompilation task:
 			if (currentCancellationTokenSource != null) {
 				currentCancellationTokenSource.Cancel();
@@ -583,10 +580,6 @@ namespace ICSharpCode.ILSpy.TextView
 		/// </summary>
 		void ShowOutput(AvalonEditTextOutput textOutput, IHighlightingDefinition highlighting = null, DecompilerTextViewState state = null)
 		{
-			textEditor.Visibility = Visibility.Visible;
-			dynamicContent.Visibility = Visibility.Hidden;
-			dynamicContent.Content = null;
-
 			Debug.WriteLine("Showing {0} characters of output", textOutput.TextLength);
 			Stopwatch w = Stopwatch.StartNew();
 
@@ -645,14 +638,6 @@ namespace ICSharpCode.ILSpy.TextView
 				model.Title = textOutput.Title;
 			}
 		}
-		
-		public void ShowContent(ILSpyTreeNode[] nodes, object content)
-		{
-			textEditor.Visibility = Visibility.Collapsed;
-			dynamicContent.Visibility = Visibility.Visible;
-			dynamicContent.Content = content;
-			decompiledNodes = nodes;
-		}
 		#endregion
 		
 		#region Decompile (for display)
@@ -1060,23 +1045,19 @@ namespace ICSharpCode.ILSpy.TextView
 			}
 		}
 		#endregion
+	}
 
-		private void self_DataContextChanged(object sender, DependencyPropertyChangedEventArgs e)
-		{
-			if (e.OldValue is DecompiledDocumentModel oldModel)
-				oldModel.TextView = null;
-			if (e.NewValue is DecompiledDocumentModel newModel)
-				newModel.TextView = this;
-		}
+	public class ViewState
+	{
+		public ILSpyTreeNode[] DecompiledNodes;
 	}
 	
-	public class DecompilerTextViewState
+	public class DecompilerTextViewState : ViewState
 	{
 		private List<Tuple<int, int>> ExpandedFoldings;
 		private int FoldingsChecksum;
 		public double VerticalOffset;
 		public double HorizontalOffset;
-		public ILSpyTreeNode[] DecompiledNodes;
 
 		public void SaveFoldingsState(IEnumerable<FoldingSection> foldings)
 		{

ILSpy/TextView/DecompilerTextView.xaml

@@ -2,8 +2,7 @@
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 			 xmlns:properties="clr-namespace:ICSharpCode.ILSpy.Properties"
-             xmlns:ae="clr-namespace:ICSharpCode.AvalonEdit;assembly=ICSharpCode.AvalonEdit"
-			 DataContextChanged="self_DataContextChanged">
+             xmlns:ae="clr-namespace:ICSharpCode.AvalonEdit;assembly=ICSharpCode.AvalonEdit">
 	<UserControl.Resources>
 		<BooleanToVisibilityConverter x:Key="boolToVisibility" />
 	</UserControl.Resources>
@@ -18,7 +17,6 @@
 						<Style TargetType="{x:Type Button}" />
 					</ae:TextEditor.Resources>
 				</ae:TextEditor>
-				<ContentControl Name="dynamicContent" />
 				<Border Name="waitAdorner" Background="#C0FFFFFF" Visibility="Collapsed">
 					<StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
 						<TextBlock FontSize="14pt" Text="{x:Static properties:Resources.Decompiling}"/>

ILSpy/TreeNodes/AssemblyTreeNode.cs

@@ -32,6 +32,7 @@ using Microsoft.Win32;
 using ICSharpCode.Decompiler.TypeSystem;
 using TypeDefinitionHandle = System.Reflection.Metadata.TypeDefinitionHandle;
 using ICSharpCode.ILSpy.Properties;
+using ICSharpCode.ILSpy.ViewModels;
 
 namespace ICSharpCode.ILSpy.TreeNodes
 {
@@ -276,7 +277,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			language.DecompileAssembly(LoadedAssembly, output, options);
 		}
 
-		public override bool Save(DecompilerTextView textView)
+		public override bool Save(TabPageModel tabPage)
 		{
 			Language language = this.Language;
 			if (string.IsNullOrEmpty(language.ProjectFileExtension))
@@ -301,7 +302,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 						}
 					}
 				}
-				textView.SaveToDisk(language, new[] { this }, options, dlg.FileName);
+				tabPage.ShowTextView(textView => textView.SaveToDisk(language, new[] { this }, options, dlg.FileName));
 			}
 			return true;
 		}

ILSpy/TreeNodes/ILSpyTreeNode.cs

@@ -64,7 +64,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 		/// This method is called on the main thread when only a single item is selected.
 		/// If it returns false, normal decompilation is used to view the item.
 		/// </summary>
-		public virtual bool View(TextView.DecompilerTextView textView)
+		public virtual bool View(ViewModels.TabPageModel tabPage)
 		{
 			return false;
 		}
@@ -74,7 +74,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 		/// This method is called on the main thread when only a single item is selected.
 		/// If it returns false, normal decompilation is used to save the item.
 		/// </summary>
-		public virtual bool Save(TextView.DecompilerTextView textView)
+		public virtual bool Save(ViewModels.TabPageModel tabPage)
 		{
 			return false;
 		}

ILSpy/TreeNodes/ResourceNodes/CursorResourceEntryNode.cs

@@ -24,6 +24,7 @@ using System.Windows.Media.Imaging;
 using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.ILSpy.Properties;
 using ICSharpCode.ILSpy.TextView;
+using ICSharpCode.ILSpy.ViewModels;
 
 namespace ICSharpCode.ILSpy.TreeNodes
 {
@@ -61,7 +62,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 
 		public override object Icon => Images.ResourceImage;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(TabPageModel tabPage)
 		{
 			try {
 				AvalonEditTextOutput output = new AvalonEditTextOutput();
@@ -90,7 +91,8 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				output.AddButton(Images.Save, Resources.Save, delegate {
 					Save(null);
 				});
-				textView.ShowNode(output, this);
+				tabPage.ShowTextView(textView => textView.ShowNode(output, this));
+				tabPage.SupportsLanguageSwitching = false;
 				return true;
 			}
 			catch (Exception) {

ILSpy/TreeNodes/ResourceNodes/IconResourceEntryNode.cs

@@ -24,6 +24,7 @@ using System.Windows.Media.Imaging;
 using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.ILSpy.Properties;
 using ICSharpCode.ILSpy.TextView;
+using ICSharpCode.ILSpy.ViewModels;
 
 namespace ICSharpCode.ILSpy.TreeNodes
 {
@@ -60,7 +61,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 
 		public override object Icon => Images.ResourceImage;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(TabPageModel tabPage)
 		{
 			try {
 				AvalonEditTextOutput output = new AvalonEditTextOutput();
@@ -74,7 +75,8 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				output.AddButton(Images.Save, Resources.Save, delegate {
 					Save(null);
 				});
-				textView.ShowNode(output, this);
+				tabPage.ShowTextView(textView => textView.ShowNode(output, this));
+				tabPage.SupportsLanguageSwitching = false;
 				return true;
 			} catch (Exception) {
 				return false;

ILSpy/TreeNodes/ResourceNodes/ImageResourceEntryNode.cs

@@ -24,6 +24,7 @@ using System.Windows.Media.Imaging;
 using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.ILSpy.Properties;
 using ICSharpCode.ILSpy.TextView;
+using ICSharpCode.ILSpy.ViewModels;
 
 namespace ICSharpCode.ILSpy.TreeNodes
 {
@@ -67,7 +68,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 
 		public override object Icon => Images.ResourceImage;
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(TabPageModel tabPage)
 		{
 			try {
 				AvalonEditTextOutput output = new AvalonEditTextOutput();
@@ -81,7 +82,8 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				output.AddButton(Images.Save, Resources.Save, delegate {
 					Save(null);
 				});
-				textView.ShowNode(output, this);
+				tabPage.ShowTextView(textView => textView.ShowNode(output, this));
+				tabPage.SupportsLanguageSwitching = false;
 				return true;
 			}
 			catch (Exception) {

ILSpy/TreeNodes/ResourceNodes/ResourceEntryNode.cs

@@ -68,7 +68,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			language.WriteCommentLine(output, string.Format("{0} = {1}", key, data));
 		}
 
-		public override bool Save(DecompilerTextView textView)
+		public override bool Save(ViewModels.TabPageModel tabPage)
 		{
 			SaveFileDialog dlg = new SaveFileDialog();
 			dlg.FileName = Path.GetFileName(DecompilerTextView.CleanUpName(key));

ILSpy/TreeNodes/ResourceNodes/ResourceTreeNode.cs

@@ -26,6 +26,7 @@ using ICSharpCode.Decompiler;
 using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.ILSpy.Properties;
 using ICSharpCode.ILSpy.TextView;
+using ICSharpCode.ILSpy.ViewModels;
 using Microsoft.Win32;
 
 namespace ICSharpCode.ILSpy.TreeNodes
@@ -65,12 +66,12 @@ namespace ICSharpCode.ILSpy.TreeNodes
 
 			ISmartTextOutput smartOutput = output as ISmartTextOutput;
 			if (smartOutput != null) {
-				smartOutput.AddButton(Images.Save, Resources.Save, delegate { Save(Docking.DockWorkspace.Instance.GetTextView()); });
+				smartOutput.AddButton(Images.Save, Resources.Save, delegate { Save(Docking.DockWorkspace.Instance.ActiveTabPage); });
 				output.WriteLine();
 			}
 		}
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(TabPageModel tabPage)
 		{
 			Stream s = Resource.TryOpenStream();
 			if (s != null && s.Length < DecompilerTextView.DefaultOutputLengthLimit) {
@@ -85,14 +86,15 @@ namespace ICSharpCode.ILSpy.TreeNodes
 						ext = ".xml";
 					else
 						ext = Path.GetExtension(DecompilerTextView.CleanUpName(Resource.Name));
-					textView.ShowNode(output, this, HighlightingManager.Instance.GetDefinitionByExtension(ext));
+					tabPage.ShowTextView(textView => textView.ShowNode(output, this, HighlightingManager.Instance.GetDefinitionByExtension(ext)));
+					tabPage.SupportsLanguageSwitching = false;
 					return true;
 				}
 			}
 			return false;
 		}
 
-		public override bool Save(DecompilerTextView textView)
+		public override bool Save(TabPageModel tabPage)
 		{
 			Stream s = Resource.TryOpenStream();
 			if (s == null)

ILSpy/TreeNodes/ResourceNodes/ResourcesFileTreeNode.cs

@@ -29,6 +29,7 @@ using ICSharpCode.ILSpy.Controls;
 using ICSharpCode.ILSpy.TextView;
 using Microsoft.Win32;
 using ICSharpCode.ILSpy.Properties;
+using ICSharpCode.ILSpy.ViewModels;
 
 namespace ICSharpCode.ILSpy.TreeNodes
 {
@@ -105,7 +106,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			}
 		}
 
-		public override bool Save(DecompilerTextView textView)
+		public override bool Save(TabPageModel tabPage)
 		{
 			Stream s = Resource.TryOpenStream();
 			if (s == null) return false;
@@ -144,12 +145,13 @@ namespace ICSharpCode.ILSpy.TreeNodes
 		{
 			EnsureLazyChildren();
 			base.Decompile(language, output, options);
+			var textView = (DecompilerTextView)Docking.DockWorkspace.Instance.ActiveTabPage.Content;
 			if (stringTableEntries.Count != 0) {
 				ISmartTextOutput smartOutput = output as ISmartTextOutput;
 				if (null != smartOutput) {
 					smartOutput.AddUIElement(
 						delegate {
-							return new ResourceStringTable(stringTableEntries, Docking.DockWorkspace.Instance.GetTextView());
+							return new ResourceStringTable(stringTableEntries, textView);
 						}
 					);
 				}
@@ -161,7 +163,7 @@ namespace ICSharpCode.ILSpy.TreeNodes
 				if (null != smartOutput) {
 					smartOutput.AddUIElement(
 						delegate {
-							return new ResourceObjectTable(otherEntries, Docking.DockWorkspace.Instance.GetTextView());
+							return new ResourceObjectTable(otherEntries, textView);
 						}
 					);
 				}

ILSpy/TreeNodes/ResourceNodes/XamlResourceNode.cs

@@ -25,6 +25,7 @@ using ICSharpCode.AvalonEdit.Highlighting;
 using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.ILSpy.TextView;
 using ICSharpCode.ILSpy.TreeNodes;
+using ICSharpCode.ILSpy.ViewModels;
 
 namespace ICSharpCode.ILSpy.Xaml
 {
@@ -53,12 +54,12 @@ namespace ICSharpCode.ILSpy.Xaml
 		{
 		}
 		
-		public override bool View(DecompilerTextView textView)
+		public override bool View(TabPageModel tabPage)
 		{
 			AvalonEditTextOutput output = new AvalonEditTextOutput();
 			IHighlightingDefinition highlighting = null;
 
-			textView.RunWithCancellation(
+			tabPage.ShowTextView(textView => textView.RunWithCancellation(
 				token => Task.Factory.StartNew(
 					() => {
 						try {
@@ -75,7 +76,8 @@ namespace ICSharpCode.ILSpy.Xaml
 						}
 						return output;
 					}, token)
-			).Then(t => textView.ShowNode(t, this, highlighting)).HandleExceptions();
+			).Then(t => textView.ShowNode(t, this, highlighting)).HandleExceptions());
+			tabPage.SupportsLanguageSwitching = false;
 			return true;
 		}
 	}

ILSpy/TreeNodes/ResourceNodes/XmlResourceNode.cs

@@ -25,6 +25,7 @@ using ICSharpCode.AvalonEdit.Highlighting;
 using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.ILSpy.TextView;
 using ICSharpCode.ILSpy.TreeNodes;
+using ICSharpCode.ILSpy.ViewModels;
 
 namespace ICSharpCode.ILSpy.Xaml
 {
@@ -79,12 +80,12 @@ namespace ICSharpCode.ILSpy.Xaml
 			}
 		}
 
-		public override bool View(DecompilerTextView textView)
+		public override bool View(TabPageModel tabPage)
 		{
 			AvalonEditTextOutput output = new AvalonEditTextOutput();
 			IHighlightingDefinition highlighting = null;
 
-			textView.RunWithCancellation(
+			tabPage.ShowTextView(textView => textView.RunWithCancellation(
 				token => Task.Factory.StartNew(
 					() => {
 						try {
@@ -102,7 +103,9 @@ namespace ICSharpCode.ILSpy.Xaml
 						}
 						return output;
 					}, token)
-			).Then(t => textView.ShowNode(t, this, highlighting)).HandleExceptions();
+			).Then(t => textView.ShowNode(t, this, highlighting))
+			.HandleExceptions());
+			tabPage.SupportsLanguageSwitching = false;
 			return true;
 		}
 	}

ILSpy/ViewModels/AnalyzerPaneModel.cs

@@ -24,8 +24,6 @@ namespace ICSharpCode.ILSpy.ViewModels
 
 		public static AnalyzerPaneModel Instance { get; } = new AnalyzerPaneModel();
 
-		public override PanePosition DefaultPosition => PanePosition.Bottom;
-
 		private AnalyzerPaneModel()
 		{
 			ContentId = PaneContentId;

ILSpy/ViewModels/AssemblyListPaneModel.cs

@@ -26,8 +26,6 @@ namespace ICSharpCode.ILSpy.ViewModels
 
 		public static AssemblyListPaneModel Instance { get; } = new AssemblyListPaneModel();
 
-		public override PanePosition DefaultPosition => PanePosition.Left;
-
 		private AssemblyListPaneModel()
 		{
 			Title = Resources.Assemblies;

ILSpy/ViewModels/DebugStepsPaneModel.cs

@@ -24,8 +24,6 @@ namespace ICSharpCode.ILSpy.ViewModels
 
 		public static DebugStepsPaneModel Instance { get; } = new DebugStepsPaneModel();
 
-		public override PanePosition DefaultPosition => PanePosition.Top;
-
 		private DebugStepsPaneModel()
 		{
 			ContentId = PaneContentId;

ILSpy/ViewModels/PaneModel.cs

@@ -59,8 +59,6 @@ namespace ICSharpCode.ILSpy.ViewModels
 			this.closeCommand = new CloseCommandImpl(this);
 		}
 
-		public abstract PanePosition DefaultPosition { get; }
-
 		public event PropertyChangedEventHandler PropertyChanged;
 
 		protected void RaisePropertyChanged(string propertyName)

ILSpy/ViewModels/SearchPaneModel.cs

@@ -24,8 +24,6 @@ namespace ICSharpCode.ILSpy.ViewModels
 
 		public static SearchPaneModel Instance { get; } = new SearchPaneModel();
 
-		public override PanePosition DefaultPosition => PanePosition.Top;
-
 		private SearchPaneModel()
 		{
 			ContentId = PaneContentId;

ILSpy/ViewModels/TabPageModel.cs

@@ -16,45 +16,15 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
-using ICSharpCode.ILSpy.Properties;
+using System;
+using System.Threading.Tasks;
+using System.Windows;
 using ICSharpCode.ILSpy.TextView;
 
 namespace ICSharpCode.ILSpy.ViewModels
 {
-	public abstract class DocumentModel : PaneModel
+	public class TabPageModel : PaneModel
 	{
-		public override PanePosition DefaultPosition => PanePosition.Document;
-
-		protected DocumentModel(string contentId, string title)
-		{
-			this.ContentId = contentId;
-			this.Title = title;
-		}
-	}
-
-	public class DecompiledDocumentModel : DocumentModel
-	{
-		public DecompiledDocumentModel()
-			: base("//Decompiled", Resources.View)
-		{
-		}
-
-		public DecompiledDocumentModel(string id, string title)
-			: base("//Decompiled/" + id, title)
-		{
-		}
-
-		private DecompilerTextView textView;
-		public DecompilerTextView TextView {
-			get => textView;
-			set {
-				if (textView != value) {
-					textView = value;
-					RaisePropertyChanged(nameof(TextView));
-				}
-			}
-		}
-
 		private Language language;
 		public Language Language {
 			get => language;
@@ -76,5 +46,56 @@ namespace ICSharpCode.ILSpy.ViewModels
 				}
 			}
 		}
+
+		private bool supportsLanguageSwitching = true;
+		public bool SupportsLanguageSwitching {
+			get => supportsLanguageSwitching;
+			set {
+				if (supportsLanguageSwitching != value) {
+					supportsLanguageSwitching = value;
+					RaisePropertyChanged(nameof(SupportsLanguageSwitching));
+				}
+			}
+		}
+
+		private object content;
+		public object Content {
+			get => content;
+			set {
+				if (content != value) {
+					content = value;
+					RaisePropertyChanged(nameof(Content));
+				}
+			}
+		}
+
+		public ViewState GetState()
+		{
+			return null;
+		}
+	}
+
+	public static class TabPageModelExtensions
+	{
+		public static Task<T> ShowTextViewAsync<T>(this TabPageModel tabPage, Func<DecompilerTextView, Task<T>> action)
+		{
+			var textView = new DecompilerTextView();
+			tabPage.Content = textView;
+			return action(textView);
+		}
+
+		public static Task ShowTextViewAsync(this TabPageModel tabPage, Func<DecompilerTextView, Task> action)
+		{
+			var textView = new DecompilerTextView();
+			tabPage.Content = textView;
+			return action(textView);
+		}
+
+		public static void ShowTextView(this TabPageModel tabPage, Action<DecompilerTextView> action)
+		{
+			var textView = new DecompilerTextView();
+			tabPage.Content = textView;
+			action(textView);
+		}
 	}
 }