Properly restore all open panes.

ILSpy/Docking/DockLayoutSettings.cs

@@ -51,9 +51,17 @@ namespace ICSharpCode.ILSpy.Docking
 		{
 			if (!Valid)
 				rawSettings = "<LayoutRoot />";
+			try {
+				Deserialize(rawSettings);
+			} catch (Exception) {
+				Deserialize("<LayoutRoot />");
+			}
 
-			using (StringReader reader = new StringReader(rawSettings)) {
-				serializer.Deserialize(reader);
+			void Deserialize(string settings)
+			{
+				using (StringReader reader = new StringReader(settings)) {
+					serializer.Deserialize(reader);
+				}
 			}
 		}
 

ILSpy/Docking/DockWorkspace.cs

@@ -25,6 +25,8 @@ using System.Threading.Tasks;
 using ICSharpCode.AvalonEdit.Highlighting;
 using ICSharpCode.ILSpy.TextView;
 using ICSharpCode.ILSpy.ViewModels;
+using Xceed.Wpf.AvalonDock.Layout;
+using Xceed.Wpf.AvalonDock.Layout.Serialization;
 
 namespace ICSharpCode.ILSpy.Docking
 {
@@ -67,6 +69,39 @@ namespace ICSharpCode.ILSpy.Docking
 			}
 		}
 
+		internal void LayoutSerializationCallback(object sender, LayoutSerializationCallbackEventArgs e)
+		{
+			switch (e.Model) {
+				case LayoutAnchorable la:
+					switch (la.ContentId) {
+						case AssemblyListPaneModel.PaneContentId:
+							e.Content = AssemblyListPaneModel.Instance;
+							break;
+						case SearchPaneModel.PaneContentId:
+							e.Content = SearchPaneModel.Instance;
+							break;
+						case AnalyzerPaneModel.PaneContentId:
+							e.Content = AnalyzerPaneModel.Instance;
+							break;
+#if DEBUG
+						case DebugStepsPaneModel.PaneContentId:
+							e.Content = DebugStepsPaneModel.Instance;
+							break;
+#endif
+						default:
+							e.Cancel = true;
+							break;
+					}
+					if (!e.Cancel) {
+						ToolPanes.Add((ToolPaneModel)e.Content);
+					}
+					break;
+				default:
+					e.Cancel = true;
+					break;
+			}
+		}
+
 		protected void RaisePropertyChanged([CallerMemberName] string propertyName = null)
 		{
 			PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));

ILSpy/Docking/PaneTemplateSelector.cs

@@ -36,6 +36,10 @@ namespace ICSharpCode.ILSpy.Docking
 
 		public override DataTemplate SelectTemplate(object item, DependencyObject container)
 		{
+			if (item == null) {
+				return base.SelectTemplate(item, container);
+			}
+
 			return Mappings.FirstOrDefault(m => m.Type == item.GetType())?.Template
 				?? base.SelectTemplate(item, container);
 		}

ILSpy/MainWindow.xaml.cs

@@ -126,7 +126,13 @@ namespace ICSharpCode.ILSpy
 
 			InitializeComponent();
 
-			sessionSettings.DockLayout.Deserialize(new XmlLayoutSerializer(DockManager));
+			XmlLayoutSerializer serializer = new XmlLayoutSerializer(DockManager);
+			serializer.LayoutSerializationCallback += DockWorkspace.Instance.LayoutSerializationCallback;
+			try {
+				sessionSettings.DockLayout.Deserialize(serializer);
+			} finally {
+				serializer.LayoutSerializationCallback -= DockWorkspace.Instance.LayoutSerializationCallback;
+			}
 
 			sessionSettings.FilterSettings.PropertyChanged += filterSettings_PropertyChanged;
 
@@ -462,8 +468,11 @@ namespace ICSharpCode.ILSpy
 
 		void MainWindow_Loaded(object sender, RoutedEventArgs e)
 		{
-			DockWorkspace.Instance.ToolPanes.Add(AssemblyListPaneModel.Instance);
-			DockWorkspace.Instance.Documents.Add(new DecompiledDocumentModel() { IsCloseable = false, Language = CurrentLanguage, LanguageVersion = CurrentLanguageVersion });
+			DockWorkspace.Instance.Documents.Add(new DecompiledDocumentModel() {
+				IsCloseable = false,
+				Language = CurrentLanguage,
+				LanguageVersion = CurrentLanguageVersion
+			});
 			DockWorkspace.Instance.ActiveDocument = DockWorkspace.Instance.Documents.First();
 
 			ILSpySettings spySettings = this.spySettingsForMainWindow_Loaded;