Fix #2205: AboutPage should always be opened in a new tab.

ILSpy/AboutPage.cs

@@ -44,7 +44,10 @@ namespace ICSharpCode.ILSpy
 	{
 		public override void Execute(object parameter)
 		{
-			MainWindow.Instance.NavigateTo(new RequestNavigateEventArgs(new Uri("resource://aboutpage"), null));
+			MainWindow.Instance.NavigateTo(
+				new RequestNavigateEventArgs(new Uri("resource://aboutpage"), null),
+				inNewTabPage: true
+			);
 		}
 
 		static readonly Uri UpdateUrl = new Uri("https://ilspy.net/updates.xml");
@@ -54,7 +57,10 @@ namespace ICSharpCode.ILSpy
 
 		public static void Display(DecompilerTextView textView)
 		{
-			AvalonEditTextOutput output = new AvalonEditTextOutput() { Title = Resources.About, EnableHyperlinks = true };
+			AvalonEditTextOutput output = new AvalonEditTextOutput() {
+				Title = Resources.About,
+				EnableHyperlinks = true
+			};
 			output.WriteLine(Resources.ILSpyVersion + RevisionClass.FullVersion);
 			if (WindowsVersionHelper.HasPackageIdentity)
 			{

ILSpy/Docking/DockWorkspace.cs

@@ -26,6 +26,7 @@ using System.Reflection;
 using System.Runtime.CompilerServices;
 using System.Threading;
 using System.Threading.Tasks;
+using System.Windows.Navigation;
 using System.Windows.Threading;
 
 using ICSharpCode.AvalonEdit.Highlighting;
@@ -96,7 +97,13 @@ namespace ICSharpCode.ILSpy.Docking
 					this.sessionSettings.FilterSettings.LanguageVersion = value.LanguageVersion;
 					var state = value.GetState();
 					if (state != null)
+					{
+						if (state.DecompiledNodes != null)
 							MainWindow.Instance.SelectNodes(state.DecompiledNodes);
+						else
+							MainWindow.Instance.NavigateTo(new RequestNavigateEventArgs(state.ViewedUri, null));
+					}
+
 					RaisePropertyChanged(nameof(ActiveTabPage));
 				}
 			}

ILSpy/MainWindow.xaml.cs

@@ -1286,10 +1286,20 @@ namespace ICSharpCode.ILSpy
 		}
 		#endregion
 
-		internal void NavigateTo(RequestNavigateEventArgs e, bool recordHistory = true)
+		internal void NavigateTo(RequestNavigateEventArgs e, bool recordHistory = true, bool inNewTabPage = false)
 		{
 			if (e.Uri.Scheme == "resource")
 			{
+				if (inNewTabPage)
+				{
+					DockWorkspace.Instance.TabPages.Add(
+						new TabPageModel() {
+							Language = CurrentLanguage,
+							LanguageVersion = CurrentLanguageVersion
+						});
+					DockWorkspace.Instance.ActiveTabPage = DockWorkspace.Instance.TabPages.Last();
+				}
+
 				if (e.Uri.Host == "aboutpage")
 				{
 					RecordHistory();

ILSpy/TextView/DecompilerTextView.cs

@@ -75,6 +75,7 @@ namespace ICSharpCode.ILSpy.TextView
 		FoldingManager foldingManager;
 		ILSpyTreeNode[] decompiledNodes;
 		Uri currentAddress;
+		string currentTitle;
 
 		DefinitionLookup definitionLookup;
 		TextSegmentCollection<ReferenceSegment> references;
@@ -163,6 +164,16 @@ namespace ICSharpCode.ILSpy.TextView
 			textEditor.TextArea.TextView.LineTransformers.Add(textMarkerService);
 
 			ContextMenuProvider.Add(this);
+
+			this.DataContextChanged += DecompilerTextView_DataContextChanged;
+		}
+
+		private void DecompilerTextView_DataContextChanged(object sender, DependencyPropertyChangedEventArgs e)
+		{
+			if (this.DataContext is PaneModel model)
+			{
+				model.Title = currentTitle ?? ILSpy.Properties.Resources.NewTab;
+			}
 		}
 
 		void RemoveEditCommand(RoutedUICommand command)
@@ -664,8 +675,12 @@ namespace ICSharpCode.ILSpy.TextView
 				this.nextDecompilationRun.TaskCompletionSource.TrySetCanceled();
 				this.nextDecompilationRun = null;
 			}
-			if (nodes != null && string.IsNullOrEmpty(textOutput.Title))
+			if (nodes != null && (string.IsNullOrEmpty(textOutput.Title) 
+				|| textOutput.Title == Properties.Resources.NewTab))
+			{
 				textOutput.Title = string.Join(", ", nodes.Select(n => n.Text));
+			}
+
 			ShowOutput(textOutput, highlighting);
 			decompiledNodes = nodes;
 		}
@@ -746,6 +761,7 @@ namespace ICSharpCode.ILSpy.TextView
 				model.Title = textOutput.Title;
 			}
 			currentAddress = textOutput.Address;
+			currentTitle = textOutput.Title;
 		}
 		#endregion