diff --git a/ICSharpCode.ILSpyX/AssemblyListManager.cs b/ICSharpCode.ILSpyX/AssemblyListManager.cs
index 8a886df5f..510af433b 100644
--- a/ICSharpCode.ILSpyX/AssemblyListManager.cs
+++ b/ICSharpCode.ILSpyX/AssemblyListManager.cs
@@ -39,7 +39,7 @@ namespace ICSharpCode.ILSpyX
 		public const string DotNet35List = ".NET 3.5";
 		public const string ASPDotNetMVC3List = "ASP.NET (MVC3)";
 
-		private ISettingsProvider settingsProvider;
+		private readonly ISettingsProvider settingsProvider;
 
 		public AssemblyListManager(ISettingsProvider settingsProvider)
 		{
@@ -69,14 +69,13 @@ namespace ICSharpCode.ILSpyX
 		/// </summary>
 		public AssemblyList LoadList(string listName)
 		{
-			this.settingsProvider = this.settingsProvider.Load();
 			AssemblyList list = DoLoadList(listName);
 			if (!AssemblyLists.Contains(list.ListName))
 				AssemblyLists.Add(list.ListName);
 			return list;
 		}
 
-		AssemblyList DoLoadList(string listName)
+		AssemblyList DoLoadList(string? listName)
 		{
 			XElement doc = this.settingsProvider["AssemblyLists"];
 			if (listName != null)
diff --git a/ICSharpCode.ILSpyX/Settings/ILSpySettings.cs b/ICSharpCode.ILSpyX/Settings/ILSpySettings.cs
index 63e94299b..c7dc899f1 100644
--- a/ICSharpCode.ILSpyX/Settings/ILSpySettings.cs
+++ b/ICSharpCode.ILSpyX/Settings/ILSpySettings.cs
@@ -34,16 +34,11 @@ namespace ICSharpCode.ILSpyX.Settings
 		/// </summary>
 		public static ISettingsFilePathProvider? SettingsFilePathProvider { get; set; }
 
-		readonly XElement root;
+		XElement root;
 
-		ILSpySettings()
+		ILSpySettings(XElement? root = null)
 		{
-			this.root = new XElement("ILSpy");
-		}
-
-		ILSpySettings(XElement root)
-		{
-			this.root = root;
+			this.root = root ?? new XElement("ILSpy");
 		}
 
 		public XElement this[XName section] {
@@ -64,13 +59,7 @@ namespace ICSharpCode.ILSpyX.Settings
 			{
 				try
 				{
-					XDocument doc = LoadWithoutCheckingCharacters(GetConfigFile());
-					if (null == doc.Root)
-					{
-						return new ILSpySettings();
-					}
-
-					return new ILSpySettings(doc.Root);
+					return new ILSpySettings(LoadFile(GetConfigFile()).Root);
 				}
 				catch (IOException)
 				{
@@ -83,7 +72,7 @@ namespace ICSharpCode.ILSpyX.Settings
 			}
 		}
 
-		static XDocument LoadWithoutCheckingCharacters(string fileName)
+		static XDocument LoadFile(string fileName)
 		{
 			return XDocument.Load(fileName, LoadOptions.None);
 		}
@@ -91,16 +80,15 @@ namespace ICSharpCode.ILSpyX.Settings
 		/// <summary>
 		/// Saves a setting section.
 		/// </summary>
-		public static void SaveSettings(XElement section)
+		public void SaveSettings(XElement section)
 		{
-			Update(
-				delegate (XElement root) {
-					XElement? existingElement = root.Element(section.Name);
-					if (existingElement != null)
-						existingElement.ReplaceWith(section);
-					else
-						root.Add(section);
-				});
+			Update(rootElement => {
+				XElement? existingElement = rootElement.Element(section.Name);
+				if (existingElement != null)
+					existingElement.ReplaceWith(section);
+				else
+					rootElement.Add(section);
+			});
 		}
 
 		/// <summary>
@@ -108,7 +96,7 @@ namespace ICSharpCode.ILSpyX.Settings
 		/// We always reload the file on updates to ensure we aren't overwriting unrelated changes performed
 		/// by another ILSpy instance.
 		/// </summary>
-		public static void Update(Action<XElement> action)
+		public void Update(Action<XElement> action)
 		{
 			using (new MutexProtector(ConfigFileMutex))
 			{
@@ -116,7 +104,7 @@ namespace ICSharpCode.ILSpyX.Settings
 				XDocument doc;
 				try
 				{
-					doc = LoadWithoutCheckingCharacters(config);
+					doc = LoadFile(config);
 				}
 				catch (IOException)
 				{
@@ -131,6 +119,7 @@ namespace ICSharpCode.ILSpyX.Settings
 				doc.Root!.SetAttributeValue("version", DecompilerVersionInfo.Major + "." + DecompilerVersionInfo.Minor + "." + DecompilerVersionInfo.Build + "." + DecompilerVersionInfo.Revision);
 				action(doc.Root);
 				doc.Save(config, SaveOptions.None);
+				this.root = doc.Root;
 			}
 		}
 
@@ -148,11 +137,6 @@ namespace ICSharpCode.ILSpyX.Settings
 			// return "ILSpy.xml";
 		}
 
-		ISettingsProvider ISettingsProvider.Load()
-		{
-			return Load();
-		}
-
 		const string ConfigFileMutex = "01A91708-49D1-410D-B8EB-4DE2662B3971";
 
 		/// <summary>
diff --git a/ICSharpCode.ILSpyX/Settings/ISettingsProvider.cs b/ICSharpCode.ILSpyX/Settings/ISettingsProvider.cs
index 3f62dba76..664acb5e2 100644
--- a/ICSharpCode.ILSpyX/Settings/ISettingsProvider.cs
+++ b/ICSharpCode.ILSpyX/Settings/ISettingsProvider.cs
@@ -22,8 +22,6 @@ using System.Linq;
 using System.Reflection;
 using System.Xml.Linq;
 
-using static System.Collections.Specialized.BitVector32;
-
 namespace ICSharpCode.ILSpyX.Settings
 {
 	public interface ISettingsProvider
@@ -31,9 +29,8 @@ namespace ICSharpCode.ILSpyX.Settings
 		XElement this[XName section] { get; }
 
 		void Update(Action<XElement> action);
-		ISettingsProvider Load();
 
-		public static ICSharpCode.Decompiler.DecompilerSettings LoadDecompilerSettings(ISettingsProvider settingsProvider)
+		public static Decompiler.DecompilerSettings LoadDecompilerSettings(ISettingsProvider settingsProvider)
 		{
 			XElement e = settingsProvider["DecompilerSettings"];
 			var newSettings = new Decompiler.DecompilerSettings();
@@ -48,7 +45,7 @@ namespace ICSharpCode.ILSpyX.Settings
 			return newSettings;
 		}
 
-		public static void SaveDecompilerSettings(XElement root, ICSharpCode.Decompiler.DecompilerSettings newSettings)
+		public static void SaveDecompilerSettings(XElement root, Decompiler.DecompilerSettings newSettings)
 		{
 			var properties = typeof(Decompiler.DecompilerSettings).GetProperties()
 				.Where(p => p.GetCustomAttribute<BrowsableAttribute>()?.Browsable != false);
diff --git a/ICSharpCode.ILSpyX/Settings/MiscSettings.cs b/ICSharpCode.ILSpyX/Settings/MiscSettings.cs
index d349764d4..c47d5cff2 100644
--- a/ICSharpCode.ILSpyX/Settings/MiscSettings.cs
+++ b/ICSharpCode.ILSpyX/Settings/MiscSettings.cs
@@ -23,12 +23,12 @@ namespace ICSharpCode.ILSpyX.Settings
 {
 	public class MiscSettings : IMiscSettings, ISettingsSection<MiscSettings>
 	{
-		private MiscSettings()
+		public MiscSettings()
 		{
 		}
 
 		public bool AllowMultipleInstances { get; set; }
-		public bool LoadPreviousAssemblies { get; set; }
+		public bool LoadPreviousAssemblies { get; set; } = true;
 
 		public static MiscSettings Load(ISettingsProvider settingsProvider)
 		{
diff --git a/ILSpy.ReadyToRun/ReadyToRunDisassembler.cs b/ILSpy.ReadyToRun/ReadyToRunDisassembler.cs
index 0b7d0ee6c..e9c11ff93 100644
--- a/ILSpy.ReadyToRun/ReadyToRunDisassembler.cs
+++ b/ILSpy.ReadyToRun/ReadyToRunDisassembler.cs
@@ -26,6 +26,7 @@ using Iced.Intel;
 using ICSharpCode.Decompiler;
 using ICSharpCode.Decompiler.IL;
 using ICSharpCode.Decompiler.Metadata;
+using ICSharpCode.ILSpy.Util;
 
 using ILCompiler.Reflection.ReadyToRun;
 using ILCompiler.Reflection.ReadyToRun.Amd64;
diff --git a/ILSpy.ReadyToRun/ReadyToRunOptions.cs b/ILSpy.ReadyToRun/ReadyToRunOptions.cs
index 365d1dd9a..1167497bb 100644
--- a/ILSpy.ReadyToRun/ReadyToRunOptions.cs
+++ b/ILSpy.ReadyToRun/ReadyToRunOptions.cs
@@ -18,6 +18,7 @@
 
 using System.Xml.Linq;
 
+using ICSharpCode.ILSpy.Util;
 using ICSharpCode.ILSpyX;
 using ICSharpCode.ILSpyX.Settings;
 
@@ -33,10 +34,8 @@ namespace ICSharpCode.ILSpy.ReadyToRun
 
 		public static string GetDisassemblyFormat(ILSpySettings settings)
 		{
-			if (settings == null)
-			{
-				settings = ILSpySettings.Load();
-			}
+			settings ??= SettingsService.Instance.SpySettings;
+
 			XElement e = settings[ns + "ReadyToRunOptions"];
 			XAttribute a = e.Attribute("DisassemblyFormat");
 			if (a == null)
@@ -51,10 +50,8 @@ namespace ICSharpCode.ILSpy.ReadyToRun
 
 		public static bool GetIsShowUnwindInfo(ILSpySettings settings)
 		{
-			if (settings == null)
-			{
-				settings = ILSpySettings.Load();
-			}
+			settings ??= SettingsService.Instance.SpySettings;
+
 			XElement e = settings[ns + "ReadyToRunOptions"];
 			XAttribute a = e.Attribute("IsShowUnwindInfo");
 
@@ -70,10 +67,8 @@ namespace ICSharpCode.ILSpy.ReadyToRun
 
 		public static bool GetIsShowDebugInfo(ILSpySettings settings)
 		{
-			if (settings == null)
-			{
-				settings = ILSpySettings.Load();
-			}
+			settings ??= SettingsService.Instance.SpySettings;
+
 			XElement e = settings[ns + "ReadyToRunOptions"];
 			XAttribute a = e.Attribute("IsShowDebugInfo");
 
@@ -89,10 +84,8 @@ namespace ICSharpCode.ILSpy.ReadyToRun
 
 		public static bool GetIsShowGCInfo(ILSpySettings settings)
 		{
-			if (settings == null)
-			{
-				settings = ILSpySettings.Load();
-			}
+			settings ??= SettingsService.Instance.SpySettings;
+
 			XElement e = settings[ns + "ReadyToRunOptions"];
 			XAttribute a = e.Attribute("IsShowGCInfo");
 
diff --git a/ILSpy/AboutPage.cs b/ILSpy/AboutPage.cs
index 43303bf88..c9e1989f4 100644
--- a/ILSpy/AboutPage.cs
+++ b/ILSpy/AboutPage.cs
@@ -42,7 +42,7 @@ namespace ICSharpCode.ILSpy
 	{
 		public override void Execute(object parameter)
 		{
-			MainWindow.Instance.NavigateTo(
+			MainWindow.Instance.AssemblyTreeModel.NavigateTo(
 				new RequestNavigateEventArgs(new Uri("resource://aboutpage"), null),
 				inNewTabPage: true
 			);
@@ -76,7 +76,7 @@ namespace ICSharpCode.ILSpy
 				CheckBox checkBox = new CheckBox();
 				checkBox.Margin = new Thickness(4);
 				checkBox.Content = Resources.AutomaticallyCheckUpdatesEveryWeek;
-				UpdateSettings settings = new UpdateSettings(ILSpySettings.Load());
+				UpdateSettings settings = new UpdateSettings(SettingsService.Instance.SpySettings);
 				checkBox.SetBinding(CheckBox.IsCheckedProperty, new Binding("AutomaticUpdateCheckEnabled") { Source = settings });
 				return new StackPanel {
 					Margin = new Thickness(0, 4, 0, 0),
diff --git a/ILSpy/App.xaml b/ILSpy/App.xaml
index 0cfda48ce..ce2e14086 100644
--- a/ILSpy/App.xaml
+++ b/ILSpy/App.xaml
@@ -1,15 +1,14 @@
 <Application x:Class="ICSharpCode.ILSpy.App"
-             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
-             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             xmlns:styles="urn:TomsToolbox.Wpf.Styles"
-             xmlns:toms="urn:TomsToolbox"
-             xmlns:themes="clr-namespace:ICSharpCode.ILSpy.Themes"
-             StartupUri="MainWindow.xaml">
+			 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+			 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+			 xmlns:styles="urn:TomsToolbox.Wpf.Styles"
+			 xmlns:toms="urn:TomsToolbox"
+			 xmlns:themes="clr-namespace:ICSharpCode.ILSpy.Themes">
 	<Application.Resources>
 		<Style x:Key="DialogWindow" TargetType="{x:Type Window}">
-			<Setter Property="ShowInTaskbar" Value="False"/>
-			<Setter Property="UseLayoutRounding" Value="True"/>
-			<Setter Property="TextOptions.TextFormattingMode" Value="Display"/>
+			<Setter Property="ShowInTaskbar" Value="False" />
+			<Setter Property="UseLayoutRounding" Value="True" />
+			<Setter Property="TextOptions.TextFormattingMode" Value="Display" />
 			<Setter Property="toms:StyleBindings.Behaviors">
 				<Setter.Value>
 					<toms:BehaviorCollection>
diff --git a/ILSpy/App.xaml.cs b/ILSpy/App.xaml.cs
index c136891a1..886a24f88 100644
--- a/ILSpy/App.xaml.cs
+++ b/ILSpy/App.xaml.cs
@@ -31,6 +31,7 @@ using System.Windows.Navigation;
 using System.Windows.Threading;
 
 using ICSharpCode.ILSpy.AppEnv;
+using ICSharpCode.ILSpy.AssemblyTree;
 using ICSharpCode.ILSpy.Options;
 using ICSharpCode.ILSpyX.Analyzers;
 using ICSharpCode.ILSpyX.Settings;
@@ -44,7 +45,6 @@ using ICSharpCode.ILSpyX.TreeView;
 
 using TomsToolbox.Composition;
 using TomsToolbox.Wpf.Composition;
-using System.ComponentModel.Composition.Hosting;
 
 namespace ICSharpCode.ILSpy
 {
@@ -69,15 +69,7 @@ namespace ICSharpCode.ILSpy
 			ILSpySettings.SettingsFilePathProvider = new ILSpySettingsFilePathProvider();
 
 			var cmdArgs = Environment.GetCommandLineArgs().Skip(1);
-			App.CommandLineArguments = CommandLineArguments.Create(cmdArgs);
-
-			bool forceSingleInstance = (App.CommandLineArguments.SingleInstance ?? true)
-				&& !MiscSettingsPanel.CurrentMiscSettings.AllowMultipleInstances;
-			if (forceSingleInstance)
-			{
-				SingleInstance.Attach();  // will auto-exit for second instance
-				SingleInstance.NewInstanceDetected += SingleInstance_NewInstanceDetected;
-			}
+			CommandLineArguments = CommandLineArguments.Create(cmdArgs);
 
 			SharpTreeNode.SetImagesProvider(new WpfWindowsTreeNodeImagesProvider());
 
@@ -85,7 +77,7 @@ namespace ICSharpCode.ILSpy
 
 			Resources.RegisterDefaultStyles();
 
-			if (!System.Diagnostics.Debugger.IsAttached)
+			if (!Debugger.IsAttached)
 			{
 				AppDomain.CurrentDomain.UnhandledException += ShowErrorBox;
 				Dispatcher.CurrentDispatcher.UnhandledException += Dispatcher_UnhandledException;
@@ -93,6 +85,14 @@ namespace ICSharpCode.ILSpy
 			TaskScheduler.UnobservedTaskException += DotNet40_UnobservedTaskException;
 			InitializeMef().GetAwaiter().GetResult();
 
+			bool forceSingleInstance = (CommandLineArguments.SingleInstance ?? true)
+									   && !SettingsService.Instance.MiscSettings.AllowMultipleInstances;
+			if (forceSingleInstance)
+			{
+				SingleInstance.Attach();  // will auto-exit for second instance
+				SingleInstance.NewInstanceDetected += SingleInstance_NewInstanceDetected;
+			}
+
 			// Register the export provider so that it can be accessed from WPF/XAML components.
 			ExportProviderLocator.Register(ExportProvider);
 			// Add data templates registered via MEF.
@@ -103,24 +103,19 @@ namespace ICSharpCode.ILSpy
 											  new RequestNavigateEventHandler(Window_RequestNavigate));
 			ILSpyTraceListener.Install();
 
-			if (App.CommandLineArguments.ArgumentsParser.IsShowingInformation)
+			if (CommandLineArguments.ArgumentsParser.IsShowingInformation)
 			{
-				MessageBox.Show(App.CommandLineArguments.ArgumentsParser.GetHelpText(), "ILSpy Command Line Arguments");
+				MessageBox.Show(CommandLineArguments.ArgumentsParser.GetHelpText(), "ILSpy Command Line Arguments");
 			}
 
-			if (App.CommandLineArguments.ArgumentsParser.RemainingArguments.Any())
+			if (CommandLineArguments.ArgumentsParser.RemainingArguments.Any())
 			{
-				string unknownArguments = string.Join(", ", App.CommandLineArguments.ArgumentsParser.RemainingArguments);
+				string unknownArguments = string.Join(", ", CommandLineArguments.ArgumentsParser.RemainingArguments);
 				MessageBox.Show(unknownArguments, "ILSpy Unknown Command Line Arguments Passed");
 			}
 		}
 
-		private static void SingleInstance_NewInstanceDetected(object sender, NewInstanceEventArgs e)
-		{
-#pragma warning disable CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
-			ICSharpCode.ILSpy.MainWindow.Instance.HandleSingleInstanceCommandLineArguments(e.Args);
-#pragma warning restore CS4014 // Because this call is not awaited, execution of the current method continues before the call is completed
-		}
+		private static void SingleInstance_NewInstanceDetected(object sender, NewInstanceEventArgs e) => ExportProvider.GetExportedValue<AssemblyListPaneModel>().HandleSingleInstanceCommandLineArguments(e.Args).HandleExceptions();
 
 		static Assembly ResolvePluginDependencies(AssemblyLoadContext context, AssemblyName assemblyName)
 		{
@@ -200,6 +195,8 @@ namespace ICSharpCode.ILSpy
 
 		protected override void OnStartup(StartupEventArgs e)
 		{
+			base.OnStartup(e);
+
 			var output = new StringBuilder();
 
 			if (StartupExceptions.FormatExceptions(output))
@@ -207,7 +204,12 @@ namespace ICSharpCode.ILSpy
 				MessageBox.Show(output.ToString(), "Sorry we crashed!");
 				Environment.Exit(1);
 			}
-			base.OnStartup(e);
+
+			MainWindow = new MainWindow();
+			MainWindow.Loaded += (sender, args) => {
+				ExportProvider.GetExportedValue<AssemblyListPaneModel>().Initialize();
+			};
+			MainWindow.Show();
 		}
 
 		void DotNet40_UnobservedTaskException(object sender, UnobservedTaskExceptionEventArgs e)
@@ -268,7 +270,7 @@ namespace ICSharpCode.ILSpy
 
 		void Window_RequestNavigate(object sender, RequestNavigateEventArgs e)
 		{
-			ILSpy.MainWindow.Instance.NavigateTo(e);
+			ExportProvider.GetExportedValue<AssemblyListPaneModel>().NavigateTo(e);
 		}
 	}
 }
\ No newline at end of file
diff --git a/ILSpy/AssemblyTree/AssemblyListPaneModel.cs b/ILSpy/AssemblyTree/AssemblyListPaneModel.cs
index 97199d059..e97b832af 100644
--- a/ILSpy/AssemblyTree/AssemblyListPaneModel.cs
+++ b/ILSpy/AssemblyTree/AssemblyListPaneModel.cs
@@ -53,6 +53,7 @@ using System.Text;
 
 using TomsToolbox.Essentials;
 using TomsToolbox.Wpf;
+using System.Windows.Navigation;
 
 namespace ICSharpCode.ILSpy.AssemblyTree
 {
@@ -151,6 +152,26 @@ namespace ICSharpCode.ILSpy.AssemblyTree
 			}
 		}
 
+		public async Task HandleSingleInstanceCommandLineArguments(string[] args)
+		{
+			var cmdArgs = CommandLineArguments.Create(args);
+
+			await Dispatcher.InvokeAsync(() => {
+
+				if (!HandleCommandLineArguments(cmdArgs))
+					return;
+
+				var window = Application.Current.MainWindow;
+
+				if (!cmdArgs.NoActivate && window is { WindowState: WindowState.Minimized })
+				{
+					window.WindowState = WindowState.Normal;
+				}
+
+				HandleCommandLineArgumentsAfterShowList(cmdArgs);
+			});
+		}
+
 		public async void NavigateOnLaunch(string navigateTo, string[] activeTreeViewPath, ILSpySettings spySettings, List<LoadedAssembly> relevantAssemblies)
 		{
 			var initialSelection = SelectedItem;
@@ -315,22 +336,11 @@ namespace ICSharpCode.ILSpy.AssemblyTree
 
 		public void Initialize()
 		{
-			var loadPreviousAssemblies = Options.MiscSettingsPanel.CurrentMiscSettings.LoadPreviousAssemblies;
-
-			var sessionSettings = SettingsService.Instance.SessionSettings;
-
-			if (loadPreviousAssemblies)
-			{
-				this.AssemblyList = SettingsService.Instance.AssemblyListManager.LoadList(sessionSettings.ActiveAssemblyList);
-			}
-			else
-			{
-				SettingsService.Instance.AssemblyListManager.ClearAll();
-				this.AssemblyList = SettingsService.Instance.AssemblyListManager.CreateList(AssemblyListManager.DefaultListName);
-			}
+			this.AssemblyList = SettingsService.Instance.LoadInitialAssemblyList();
 
 			HandleCommandLineArguments(App.CommandLineArguments);
 
+			var loadPreviousAssemblies = SettingsService.Instance.MiscSettings.LoadPreviousAssemblies;
 			if (AssemblyList.GetAssemblies().Length == 0
 				&& AssemblyList.ListName == AssemblyListManager.DefaultListName
 				&& loadPreviousAssemblies)
@@ -340,6 +350,7 @@ namespace ICSharpCode.ILSpy.AssemblyTree
 
 			ShowAssemblyList(this.AssemblyList);
 
+			var sessionSettings = SettingsService.Instance.SessionSettings;
 			if (sessionSettings.ActiveAutoLoadedAssembly != null
 				&& File.Exists(sessionSettings.ActiveAutoLoadedAssembly))
 			{
@@ -742,7 +753,7 @@ namespace ICSharpCode.ILSpy.AssemblyTree
 			}
 			if (newState?.ViewedUri != null)
 			{
-				MainWindow.Instance.NavigateTo(new(newState.ViewedUri, null), recordHistory: false);
+				MainWindow.Instance.AssemblyTreeModel.NavigateTo(new(newState.ViewedUri, null), recordHistory: false);
 				return;
 			}
 
@@ -768,6 +779,72 @@ namespace ICSharpCode.ILSpy.AssemblyTree
 
 		#endregion
 
+		public void NavigateHistory(bool forward)
+		{
+			TabPageModel tabPage = DockWorkspace.Instance.ActiveTabPage;
+			var state = tabPage.GetState();
+			if (state != null)
+				history.UpdateCurrent(new NavigationState(tabPage, state));
+			var newState = forward ? history.GoForward() : history.GoBack();
+
+			DockWorkspace.Instance.ActiveTabPage = newState.TabPage;
+
+			SelectNodes(newState.TreeNodes, ignoreCompilationRequests: true);
+			DecompileSelectedNodes(newState.ViewState as DecompilerTextViewState, false);
+		}
+
+		internal void NavigateTo(RequestNavigateEventArgs e, bool recordHistory = true, bool inNewTabPage = false)
+		{
+			if (e.Uri.Scheme == "resource")
+			{
+				if (inNewTabPage)
+				{
+					DockWorkspace.Instance.AddTabPage();
+				}
+
+				if (e.Uri.Host == "aboutpage")
+				{
+					RecordHistory();
+					DockWorkspace.Instance.ActiveTabPage.ShowTextView(AboutPage.Display);
+					e.Handled = true;
+					return;
+				}
+				AvalonEditTextOutput output = new AvalonEditTextOutput {
+					Address = e.Uri,
+					Title = e.Uri.AbsolutePath,
+					EnableHyperlinks = true
+				};
+				using (Stream s = typeof(App).Assembly.GetManifestResourceStream(typeof(App), e.Uri.AbsolutePath))
+				{
+					using (StreamReader r = new StreamReader(s))
+					{
+						string line;
+						while ((line = r.ReadLine()) != null)
+						{
+							output.Write(line);
+							output.WriteLine();
+						}
+					}
+				}
+				RecordHistory();
+				DockWorkspace.Instance.ShowText(output);
+				e.Handled = true;
+			}
+
+			void RecordHistory()
+			{
+				if (!recordHistory)
+					return;
+				TabPageModel tabPage = DockWorkspace.Instance.ActiveTabPage;
+				var currentState = tabPage.GetState();
+				if (currentState != null)
+					history.UpdateCurrent(new NavigationState(tabPage, currentState));
+
+				UnselectAll(ignoreCompilationRequests: true);
+
+				history.Record(new NavigationState(tabPage, new ViewState { ViewedUri = e.Uri }));
+			}
+		}
 
 		public void Refresh()
 		{
diff --git a/ILSpy/Commands/CheckForUpdatesCommand.cs b/ILSpy/Commands/CheckForUpdatesCommand.cs
index 58438c604..69e28573c 100644
--- a/ILSpy/Commands/CheckForUpdatesCommand.cs
+++ b/ILSpy/Commands/CheckForUpdatesCommand.cs
@@ -35,7 +35,7 @@ namespace ICSharpCode.ILSpy
 
 		public override async void Execute(object parameter)
 		{
-			await MainWindow.Instance.ShowMessageIfUpdatesAvailableAsync(ILSpySettings.Load(), forceCheck: true);
+			await MainWindow.Instance.ShowMessageIfUpdatesAvailableAsync(SettingsService.Instance.SpySettings, forceCheck: true);
 		}
 	}
 }
diff --git a/ILSpy/Docking/DockWorkspace.cs b/ILSpy/Docking/DockWorkspace.cs
index f0b90967d..9ca68cc26 100644
--- a/ILSpy/Docking/DockWorkspace.cs
+++ b/ILSpy/Docking/DockWorkspace.cs
@@ -59,6 +59,9 @@ namespace ICSharpCode.ILSpy.Docking
 			TabPages = new(tabPages);
 			ToolPanes = new(toolPanes);
 
+			// Make sure there is at least one tab open
+			AddTabPage();
+
 			MessageBus<CurrentAssemblyListChangedEventArgs>.Subscribers += (sender, e) => CurrentAssemblyList_Changed(sender, e);
 		}
 
@@ -146,7 +149,7 @@ namespace ICSharpCode.ILSpy.Docking
 					return;
 				}
 
-				var state = value.GetState();
+				var state = value?.GetState();
 				if (state != null)
 				{
 					if (state.DecompiledNodes != null)
@@ -155,7 +158,7 @@ namespace ICSharpCode.ILSpy.Docking
 					}
 					else
 					{
-						MainWindow.Instance.NavigateTo(new(state.ViewedUri, null));
+						MainWindow.Instance.AssemblyTreeModel.NavigateTo(new(state.ViewedUri, null));
 					}
 				}
 			}
diff --git a/ILSpy/ILSpy.csproj b/ILSpy/ILSpy.csproj
index 36a8e7b44..9b0dd6259 100644
--- a/ILSpy/ILSpy.csproj
+++ b/ILSpy/ILSpy.csproj
@@ -1,5 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <OutputType>WinExe</OutputType>
diff --git a/ILSpy/Languages/Languages.cs b/ILSpy/Languages/Languages.cs
index a58df78da..a41dfa896 100644
--- a/ILSpy/Languages/Languages.cs
+++ b/ILSpy/Languages/Languages.cs
@@ -16,6 +16,8 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
+#nullable enable
+
 using System;
 using System.Collections.ObjectModel;
 using System.Linq;
@@ -53,6 +55,7 @@ namespace ICSharpCode.ILSpy
 		}
 
 		static ILLanguage ilLanguage;
+
 		public static ILLanguage ILLanguage {
 			get {
 				if (ilLanguage == null)
diff --git a/ILSpy/MainWindow.xaml b/ILSpy/MainWindow.xaml
index 8b253493a..4e7df1d72 100644
--- a/ILSpy/MainWindow.xaml
+++ b/ILSpy/MainWindow.xaml
@@ -1,25 +1,24 @@
 <?xml version="1.0" encoding="utf-8"?>
-
 <Window x:Class="ICSharpCode.ILSpy.MainWindow"
-        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
-        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-        xmlns:local="clr-namespace:ICSharpCode.ILSpy"
-        xmlns:avalondock="https://github.com/Dirkster99/AvalonDock"
-        xmlns:controls="clr-namespace:ICSharpCode.ILSpy.Controls"
-        xmlns:docking="clr-namespace:ICSharpCode.ILSpy.Docking"
-        xmlns:properties="clr-namespace:ICSharpCode.ILSpy.Properties"
-        Title="ILSpy"
-        MinWidth="250"
-        MinHeight="200"
-        UseLayoutRounding="True"
-        TextOptions.TextFormattingMode="Display"
-        xmlns:d="http://schemas.microsoft.com/expression/blend/2008" d:DesignHeight="500" d:DesignWidth="500"
-        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d"
-        xmlns:b="http://schemas.microsoft.com/xaml/behaviors"
-        xmlns:themes="clr-namespace:ICSharpCode.ILSpy.Themes"
-        xmlns:toms="urn:TomsToolbox"
-        xmlns:viewModels="clr-namespace:ICSharpCode.ILSpy.ViewModels"
-        d:DataContext="{d:DesignInstance local:MainWindowViewModel}">
+		xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+		xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+		xmlns:local="clr-namespace:ICSharpCode.ILSpy"
+		xmlns:avalondock="https://github.com/Dirkster99/AvalonDock"
+		xmlns:controls="clr-namespace:ICSharpCode.ILSpy.Controls"
+		xmlns:docking="clr-namespace:ICSharpCode.ILSpy.Docking"
+		xmlns:properties="clr-namespace:ICSharpCode.ILSpy.Properties"
+		Title="ILSpy"
+		MinWidth="250"
+		MinHeight="200"
+		UseLayoutRounding="True"
+		TextOptions.TextFormattingMode="Display"
+		xmlns:d="http://schemas.microsoft.com/expression/blend/2008" d:DesignHeight="500" d:DesignWidth="500"
+		xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d"
+		xmlns:b="http://schemas.microsoft.com/xaml/behaviors"
+		xmlns:themes="clr-namespace:ICSharpCode.ILSpy.Themes"
+		xmlns:toms="urn:TomsToolbox"
+		xmlns:viewModels="clr-namespace:ICSharpCode.ILSpy.ViewModels"
+		d:DataContext="{d:DesignInstance local:MainWindowViewModel}">
 	<Window.Resources>
 
 		<DataTemplate DataType="{x:Type viewModels:TabPageModel}">
@@ -77,11 +76,11 @@
 			<!-- contents of file menu are added using MEF -->
 			<MenuItem Header="{x:Static properties:Resources._View}" Tag="_View">
 				<MenuItem Header="{x:Static properties:Resources.Show_publiconlyTypesMembers}" IsCheckable="True"
-				          IsChecked="{Binding SessionSettings.LanguageSettings.ApiVisPublicOnly}" />
+						  IsChecked="{Binding SessionSettings.LanguageSettings.ApiVisPublicOnly}" />
 				<MenuItem Header="{x:Static properties:Resources.Show_internalTypesMembers}" IsCheckable="True"
-				          IsChecked="{Binding SessionSettings.LanguageSettings.ApiVisPublicAndInternal}" />
+						  IsChecked="{Binding SessionSettings.LanguageSettings.ApiVisPublicAndInternal}" />
 				<MenuItem Header="{x:Static properties:Resources.Show_allTypesAndMembers}" IsCheckable="True"
-				          IsChecked="{Binding SessionSettings.LanguageSettings.ApiVisAll}" />
+						  IsChecked="{Binding SessionSettings.LanguageSettings.ApiVisAll}" />
 				<Separator />
 				<MenuItem Header="{x:Static properties:Resources.Theme}" ItemsSource="{x:Static themes:ThemeManager.AllThemes}">
 					<MenuItem.ItemContainerStyle>
@@ -103,11 +102,11 @@
 				</MenuItem>
 				<MenuItem Header="{x:Static properties:Resources.UILanguage}">
 					<MenuItem Header="{x:Static properties:Resources.UILanguage_System}" IsCheckable="True"
-					          IsChecked="{Binding SessionSettings.CurrentCulture, Converter={controls:CultureSelectionConverter}, ConverterParameter={x:Null}}" />
+							  IsChecked="{Binding SessionSettings.CurrentCulture, Converter={controls:CultureSelectionConverter}, ConverterParameter={x:Null}}" />
 					<MenuItem Header="English" IsCheckable="True"
-					          IsChecked="{Binding SessionSettings.CurrentCulture, Converter={controls:CultureSelectionConverter}, ConverterParameter=en-US}" />
+							  IsChecked="{Binding SessionSettings.CurrentCulture, Converter={controls:CultureSelectionConverter}, ConverterParameter=en-US}" />
 					<MenuItem Header="中文" IsCheckable="True"
-					          IsChecked="{Binding SessionSettings.CurrentCulture, Converter={controls:CultureSelectionConverter}, ConverterParameter=zh-Hans}" />
+							  IsChecked="{Binding SessionSettings.CurrentCulture, Converter={controls:CultureSelectionConverter}, ConverterParameter=zh-Hans}" />
 				</MenuItem>
 			</MenuItem>
 			<MenuItem Header="{x:Static properties:Resources._Window}" Tag="_Window" />
@@ -143,42 +142,42 @@
 			<!-- 'Open' toolbar category is inserted here -->
 			<Separator />
 			<ComboBox Name="assemblyListComboBox" Width="100" MaxDropDownHeight="Auto"
-			          ItemsSource="{Binding AssemblyListManager.AssemblyLists}"
-			          ToolTip="{x:Static properties:Resources.SelectAssemblyListDropdownTooltip}"
-			          SelectedItem="{Binding SessionSettings.ActiveAssemblyList}" />
+					  ItemsSource="{Binding AssemblyListManager.AssemblyLists}"
+					  ToolTip="{x:Static properties:Resources.SelectAssemblyListDropdownTooltip}"
+					  SelectedItem="{Binding SessionSettings.ActiveAssemblyList}" />
 			<Button Command="{x:Static local:ILSpyCommands.ManageAssemblyListsCommand}"
-			        ToolTip="{x:Static properties:Resources.ManageAssemblyLists}">
+					ToolTip="{x:Static properties:Resources.ManageAssemblyLists}">
 				<Image Width="16" Height="16" Source="{controls:XamlResource Images/AssemblyList}"
-				       Style="{StaticResource DarkModeAwareImageStyle}" />
+					   Style="{StaticResource DarkModeAwareImageStyle}" />
 			</Button>
 			<Separator />
 			<CheckBox IsChecked="{Binding SessionSettings.LanguageSettings.ApiVisPublicOnly}"
-			          ToolTip="{x:Static properties:Resources.ShowPublicOnlyTypesMembers}">
+					  ToolTip="{x:Static properties:Resources.ShowPublicOnlyTypesMembers}">
 				<Image Width="16" Height="16" Source="{controls:XamlResource Images/ShowPublicOnly}"
-				       Style="{StaticResource DarkModeAwareImageStyle}" />
+					   Style="{StaticResource DarkModeAwareImageStyle}" />
 			</CheckBox>
 			<CheckBox IsChecked="{Binding SessionSettings.LanguageSettings.ApiVisPublicAndInternal}"
-			          ToolTip="{x:Static properties:Resources.ShowInternalTypesMembers}">
+					  ToolTip="{x:Static properties:Resources.ShowInternalTypesMembers}">
 				<Image Width="16" Height="16" Source="{controls:XamlResource Images/ShowPrivateInternal}"
-				       Style="{StaticResource DarkModeAwareImageStyle}" />
+					   Style="{StaticResource DarkModeAwareImageStyle}" />
 			</CheckBox>
 			<CheckBox IsChecked="{Binding SessionSettings.LanguageSettings.ApiVisAll}"
-			          ToolTip="{x:Static properties:Resources.ShowAllTypesAndMembers}">
+					  ToolTip="{x:Static properties:Resources.ShowAllTypesAndMembers}">
 				<Image Width="16" Height="16" Source="{controls:XamlResource Images/ShowAll}"
-				       Style="{StaticResource DarkModeAwareImageStyle}" />
+					   Style="{StaticResource DarkModeAwareImageStyle}" />
 			</CheckBox>
 			<Separator />
 			<ComboBox Name="languageComboBox" DisplayMemberPath="Name" Width="100" MaxDropDownHeight="Auto"
-			          IsEnabled="{Binding Workspace.ActiveTabPage.SupportsLanguageSwitching}"
-			          ItemsSource="{x:Static local:Languages.AllLanguages}"
-			          ToolTip="{x:Static properties:Resources.SelectLanguageDropdownTooltip}"
-			          SelectedItem="{Binding SessionSettings.LanguageSettings.Language}" />
+					  IsEnabled="{Binding Workspace.ActiveTabPage.SupportsLanguageSwitching}"
+					  ItemsSource="{x:Static local:Languages.AllLanguages}"
+					  ToolTip="{x:Static properties:Resources.SelectLanguageDropdownTooltip}"
+					  SelectedItem="{Binding SessionSettings.LanguageSettings.Language}" />
 			<ComboBox Name="languageVersionComboBox" DisplayMemberPath="DisplayName" Width="120" MaxDropDownHeight="Auto"
-			          ToolTip="{x:Static properties:Resources.SelectVersionDropdownTooltip}"
-			          Visibility="{Binding SelectedItem.HasLanguageVersions, ElementName=languageComboBox, Converter={toms:BooleanToVisibilityConverter}}"
-			          IsEnabled="{Binding Workspace.ActiveTabPage.SupportsLanguageSwitching}"
-			          ItemsSource="{Binding SelectedItem.LanguageVersions, ElementName=languageComboBox, UpdateSourceTrigger=PropertyChanged}"
-			          SelectedItem="{Binding SessionSettings.LanguageSettings.LanguageVersion, UpdateSourceTrigger=PropertyChanged}" />
+					  ToolTip="{x:Static properties:Resources.SelectVersionDropdownTooltip}"
+					  Visibility="{Binding SelectedItem.HasLanguageVersions, ElementName=languageComboBox, Converter={toms:BooleanToVisibilityConverter}}"
+					  IsEnabled="{Binding Workspace.ActiveTabPage.SupportsLanguageSwitching}"
+					  ItemsSource="{Binding SelectedItem.LanguageVersions, ElementName=languageComboBox, UpdateSourceTrigger=PropertyChanged}"
+					  SelectedItem="{Binding SessionSettings.LanguageSettings.LanguageVersion, UpdateSourceTrigger=PropertyChanged}" />
 		</ToolBar>
 		<!-- Update panel -->
 		<Border DockPanel.Dock="Top" BorderBrush="Black" BorderThickness="1" Name="updatePanel" Visibility="Collapsed">
@@ -186,9 +185,9 @@
 				<Button DockPanel.Dock="Right" Click="UpdatePanelCloseButtonClick" MinWidth="0">X</Button>
 				<StackPanel Orientation="Horizontal">
 					<TextBlock Name="updatePanelMessage" Margin="4,0" VerticalAlignment="Center"
-					           Text="{x:Static properties:Resources.ILSpyVersionAvailable}" />
+							   Text="{x:Static properties:Resources.ILSpyVersionAvailable}" />
 					<Button Name="downloadOrCheckUpdateButton" Click="downloadOrCheckUpdateButtonClick"
-					        Content="{x:Static properties:Resources.Download}" />
+							Content="{x:Static properties:Resources.Download}" />
 				</StackPanel>
 			</DockPanel>
 		</Border>
@@ -196,19 +195,19 @@
 		<StatusBar x:Name="statusBar" DockPanel.Dock="Bottom" Height="26" Visibility="Collapsed">
 			<StatusBarItem DockPanel.Dock="Right">
 				<TextBlock VerticalAlignment="Center"
-				           HorizontalAlignment="Right"
-				           x:Name="statusLabel"
-				           ToolTip="{x:Static properties:Resources.Status}"
-				           Text="{x:Static properties:Resources.StandBy}" />
+						   HorizontalAlignment="Right"
+						   x:Name="statusLabel"
+						   ToolTip="{x:Static properties:Resources.Status}"
+						   Text="{x:Static properties:Resources.StandBy}" />
 			</StatusBarItem>
 		</StatusBar>
 
 		<avalondock:DockingManager x:Name="dockManager"
-		                           DataContext="{Binding Workspace}"
-		                           AnchorablesSource="{Binding ToolPanes}"
-		                           DocumentsSource="{Binding TabPages}"
-		                           ActiveContent="{Binding ActiveTabPage, Mode=TwoWay, Converter={docking:TabPageGuardConverter}}"
-		                           AllowMixedOrientation="True">
+								   DataContext="{Binding Workspace}"
+								   AnchorablesSource="{Binding ToolPanes}"
+								   DocumentsSource="{Binding TabPages}"
+								   ActiveContent="{Binding ActiveTabPage, Mode=TwoWay, Converter={docking:TabPageGuardConverter}}"
+								   AllowMixedOrientation="True">
 
 			<avalondock:DockingManager.DocumentHeaderTemplate>
 				<DataTemplate DataType="{x:Type viewModels:PaneModel}">
diff --git a/ILSpy/MainWindow.xaml.cs b/ILSpy/MainWindow.xaml.cs
index 7b1e2b1d6..396bcdd32 100644
--- a/ILSpy/MainWindow.xaml.cs
+++ b/ILSpy/MainWindow.xaml.cs
@@ -21,25 +21,21 @@ using System.ComponentModel;
 using System.Diagnostics;
 using System.Drawing;
 using System.Globalization;
-using System.IO;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Input;
 using System.Windows.Media;
-using System.Windows.Navigation;
 
 using AvalonDock.Layout.Serialization;
 
-using ICSharpCode.ILSpy.AppEnv;
 using ICSharpCode.ILSpy.AssemblyTree;
 using ICSharpCode.ILSpy.Docking;
 using ICSharpCode.ILSpy.Search;
 using ICSharpCode.ILSpy.TextView;
 using ICSharpCode.ILSpy.TreeNodes;
 using ICSharpCode.ILSpy.Updates;
-using ICSharpCode.ILSpy.ViewModels;
 using ICSharpCode.ILSpyX.FileLoaders;
 using ICSharpCode.ILSpyX.Settings;
 using ICSharpCode.ILSpyX.TreeView;
@@ -89,6 +85,7 @@ namespace ICSharpCode.ILSpy
 			{
 				Thread.CurrentThread.CurrentUICulture = new CultureInfo(sessionSettings.CurrentCulture);
 			}
+
 			InitializeComponent();
 
 			DockWorkspace.Instance.InitializeLayout(dockManager);
@@ -96,8 +93,6 @@ namespace ICSharpCode.ILSpy
 			MenuService.Instance.Init(mainMenu, toolBar, InputBindings);
 
 			InitFileLoaders();
-
-			this.Loaded += MainWindow_Loaded;
 		}
 
 		void SetWindowBounds(Rect bounds)
@@ -132,19 +127,12 @@ namespace ICSharpCode.ILSpy
 			var sessionSettings = SettingsService.Instance.SessionSettings;
 
 			// Validate and Set Window Bounds
-			Rect bounds = Rect.Transform(sessionSettings.WindowBounds, source?.CompositionTarget?.TransformToDevice ?? Matrix.Identity);
-			var boundsRect = new Rectangle((int)bounds.Left, (int)bounds.Top, (int)bounds.Width, (int)bounds.Height);
-			bool boundsOK = false;
-			foreach (var screen in Screen.AllScreens)
-			{
-				var intersection = Rectangle.Intersect(boundsRect, screen.WorkingArea);
-				if (intersection.Width > 10 && intersection.Height > 10)
-					boundsOK = true;
-			}
-			if (boundsOK)
-				SetWindowBounds(sessionSettings.WindowBounds);
-			else
-				SetWindowBounds(SessionSettings.DefaultWindowBounds);
+			var windowBounds = Rect.Transform(sessionSettings.WindowBounds, source?.CompositionTarget?.TransformToDevice ?? Matrix.Identity);
+			var boundsRect = new Rectangle((int)windowBounds.Left, (int)windowBounds.Top, (int)windowBounds.Width, (int)windowBounds.Height);
+
+			bool areBoundsValid = Screen.AllScreens.Any(screen => Rectangle.Intersect(boundsRect, screen.WorkingArea) is { Width: > 10, Height: > 10 });
+
+			SetWindowBounds(areBoundsValid ? sessionSettings.WindowBounds : SessionSettings.DefaultWindowBounds);
 
 			this.WindowState = sessionSettings.WindowState;
 		}
@@ -174,28 +162,6 @@ namespace ICSharpCode.ILSpy
 			}
 		}
 
-		internal async Task HandleSingleInstanceCommandLineArguments(string[] args)
-		{
-			var cmdArgs = CommandLineArguments.Create(args);
-
-			await Dispatcher.InvokeAsync(() => {
-				if (AssemblyTreeModel.HandleCommandLineArguments(cmdArgs))
-				{
-					if (!cmdArgs.NoActivate && WindowState == WindowState.Minimized)
-						WindowState = WindowState.Normal;
-
-					AssemblyTreeModel.HandleCommandLineArgumentsAfterShowList(cmdArgs);
-				}
-			});
-		}
-
-		void MainWindow_Loaded(object sender, RoutedEventArgs e)
-		{
-			DockWorkspace.Instance.AddTabPage();
-
-			AssemblyTreeModel.Initialize();
-		}
-
 		#region Update Check
 		string updateAvailableDownloadUrl;
 
@@ -229,7 +195,7 @@ namespace ICSharpCode.ILSpy
 			else
 			{
 				updatePanel.Visibility = Visibility.Collapsed;
-				string downloadUrl = await NotifyOfUpdatesStrategy.CheckForUpdatesAsync(ILSpySettings.Load());
+				string downloadUrl = await NotifyOfUpdatesStrategy.CheckForUpdatesAsync(SettingsService.Instance.SpySettings);
 				AdjustUpdateUIAfterCheck(downloadUrl, true);
 			}
 		}
@@ -340,7 +306,7 @@ namespace ICSharpCode.ILSpy
 			if (history.CanNavigateBack)
 			{
 				e.Handled = true;
-				NavigateHistory(false);
+				AssemblyTreeModel.NavigateHistory(false);
 			}
 		}
 
@@ -355,77 +321,11 @@ namespace ICSharpCode.ILSpy
 			if (history.CanNavigateForward)
 			{
 				e.Handled = true;
-				NavigateHistory(true);
+				AssemblyTreeModel.NavigateHistory(true);
 			}
 		}
-
-		void NavigateHistory(bool forward)
-		{
-			TabPageModel tabPage = DockWorkspace.Instance.ActiveTabPage;
-			var state = tabPage.GetState();
-			if (state != null)
-				history.UpdateCurrent(new NavigationState(tabPage, state));
-			var newState = forward ? history.GoForward() : history.GoBack();
-
-			DockWorkspace.Instance.ActiveTabPage = newState.TabPage;
-
-			AssemblyTreeModel.SelectNodes(newState.TreeNodes, ignoreCompilationRequests: true);
-			AssemblyTreeModel.DecompileSelectedNodes(newState.ViewState as DecompilerTextViewState, false);
-		}
 		#endregion
 
-		internal void NavigateTo(RequestNavigateEventArgs e, bool recordHistory = true, bool inNewTabPage = false)
-		{
-			if (e.Uri.Scheme == "resource")
-			{
-				if (inNewTabPage)
-				{
-					DockWorkspace.Instance.AddTabPage();
-				}
-
-				if (e.Uri.Host == "aboutpage")
-				{
-					RecordHistory();
-					DockWorkspace.Instance.ActiveTabPage.ShowTextView(AboutPage.Display);
-					e.Handled = true;
-					return;
-				}
-				AvalonEditTextOutput output = new AvalonEditTextOutput {
-					Address = e.Uri,
-					Title = e.Uri.AbsolutePath,
-					EnableHyperlinks = true
-				};
-				using (Stream s = typeof(App).Assembly.GetManifestResourceStream(typeof(App), e.Uri.AbsolutePath))
-				{
-					using (StreamReader r = new StreamReader(s))
-					{
-						string line;
-						while ((line = r.ReadLine()) != null)
-						{
-							output.Write(line);
-							output.WriteLine();
-						}
-					}
-				}
-				RecordHistory();
-				DockWorkspace.Instance.ShowText(output);
-				e.Handled = true;
-			}
-
-			void RecordHistory()
-			{
-				if (!recordHistory)
-					return;
-				TabPageModel tabPage = DockWorkspace.Instance.ActiveTabPage;
-				var currentState = tabPage.GetState();
-				if (currentState != null)
-					history.UpdateCurrent(new NavigationState(tabPage, currentState));
-
-				AssemblyTreeModel.UnselectAll(ignoreCompilationRequests: true);
-				history.Record(new NavigationState(tabPage, new ViewState { ViewedUri = e.Uri }));
-			}
-		}
-
 		protected override void OnStateChanged(EventArgs e)
 		{
 			base.OnStateChanged(e);
@@ -447,21 +347,18 @@ namespace ICSharpCode.ILSpy
 			sessionSettings.Save();
 		}
 
-		private string GetAutoLoadedAssemblyNode(SharpTreeNode node)
+		private static string GetAutoLoadedAssemblyNode(SharpTreeNode node)
 		{
-			if (node == null)
-				return null;
-			while (!(node is AssemblyTreeNode) && node.Parent != null)
-			{
-				node = node.Parent;
-			}
-			//this should be an assembly node
-			var assyNode = node as AssemblyTreeNode;
-			var loadedAssy = assyNode.LoadedAssembly;
-			if (!(loadedAssy.IsLoaded && loadedAssy.IsAutoLoaded))
-				return null;
+			var assemblyTreeNode = node?
+				.AncestorsAndSelf()
+				.OfType<AssemblyTreeNode>()
+				.FirstOrDefault();
+
+			var loadedAssembly = assemblyTreeNode?.LoadedAssembly;
 
-			return loadedAssy.FileName;
+			return loadedAssembly is not { IsLoaded: true, IsAutoLoaded: true }
+				? null
+				: loadedAssembly.FileName;
 		}
 	}
 }
diff --git a/ILSpy/Options/MiscSettingsPanel.xaml b/ILSpy/Options/MiscSettingsPanel.xaml
index 502f65fcc..09a9c5485 100644
--- a/ILSpy/Options/MiscSettingsPanel.xaml
+++ b/ILSpy/Options/MiscSettingsPanel.xaml
@@ -11,7 +11,7 @@
 			<StackPanel Margin="10">
 				<CheckBox IsChecked="{Binding AllowMultipleInstances}" Content="{x:Static properties:Resources.AllowMultipleInstances}" />
 				<CheckBox IsChecked="{Binding LoadPreviousAssemblies}" Content="{x:Static properties:Resources.LoadAssembliesThatWereLoadedInTheLastInstance}"/>
-				<Button Command="{Binding AddRemoveShellIntegrationCommand}" IsEnabled="{Binding EnableShellIntegrationCommand}" Content="{Binding AddRemoveShellIntegrationText}" Margin="3" />
+				<Button Command="{Binding AddRemoveShellIntegrationCommand}" Content="{Binding AddRemoveShellIntegrationText}" Margin="3" />
 			</StackPanel>
 		</GroupBox>
 	</StackPanel>
diff --git a/ILSpy/Options/MiscSettingsPanel.xaml.cs b/ILSpy/Options/MiscSettingsPanel.xaml.cs
index ac98981dd..8fc6ea04f 100644
--- a/ILSpy/Options/MiscSettingsPanel.xaml.cs
+++ b/ILSpy/Options/MiscSettingsPanel.xaml.cs
@@ -38,35 +38,25 @@ namespace ICSharpCode.ILSpy.Options
 
 		public void Load(ILSpySettings settings)
 		{
-			this.DataContext = LoadMiscSettings(settings);
-		}
-
-		static MiscSettingsViewModel currentMiscSettings;
-
-		public static MiscSettingsViewModel CurrentMiscSettings {
-			get {
-				return currentMiscSettings ?? (currentMiscSettings = LoadMiscSettings(ILSpySettings.Load()));
-			}
-		}
-
-		public static MiscSettingsViewModel LoadMiscSettings(ILSpySettings settings)
-		{
-			var s = MiscSettings.Load(settings);
-			return new MiscSettingsViewModel(s);
+			this.DataContext = new MiscSettingsViewModel(SettingsService.Instance.MiscSettings);
 		}
 
 		public void Save(XElement root)
 		{
-			var s = (MiscSettingsViewModel)this.DataContext;
-			IMiscSettings.Save(root, s);
+			if (DataContext is not IMiscSettings miscSettings)
+				return;
+
+			IMiscSettings.Save(root, miscSettings);
 
-			currentMiscSettings = null; // invalidate cached settings
+			SettingsService.Instance.MiscSettings = new() {
+				AllowMultipleInstances = miscSettings.AllowMultipleInstances,
+				LoadPreviousAssemblies = miscSettings.LoadPreviousAssemblies
+			};
 		}
 
 		public void LoadDefaults()
 		{
-			currentMiscSettings = new MiscSettingsViewModel(MiscSettings.Load(ILSpySettings.Load()));
-			this.DataContext = currentMiscSettings;
+			this.DataContext = new MiscSettingsViewModel(new());
 		}
 	}
 }
diff --git a/ILSpy/Options/MiscSettingsViewModel.cs b/ILSpy/Options/MiscSettingsViewModel.cs
index de505c349..aee87315e 100644
--- a/ILSpy/Options/MiscSettingsViewModel.cs
+++ b/ILSpy/Options/MiscSettingsViewModel.cs
@@ -24,14 +24,15 @@ using System.Windows;
 using System.Windows.Input;
 
 using ICSharpCode.ILSpy.AppEnv;
-using ICSharpCode.ILSpy.Commands;
 using ICSharpCode.ILSpyX.Settings;
 
 using Microsoft.Win32;
 
+using TomsToolbox.Wpf;
+
 namespace ICSharpCode.ILSpy.Options
 {
-	public class MiscSettingsViewModel : IMiscSettings, INotifyPropertyChanged
+	public class MiscSettingsViewModel : ObservableObject, IMiscSettings
 	{
 		bool allowMultipleInstances;
 		bool loadPreviousAssemblies = true;
@@ -40,65 +41,53 @@ namespace ICSharpCode.ILSpy.Options
 		{
 			AllowMultipleInstances = s.AllowMultipleInstances;
 			LoadPreviousAssemblies = s.LoadPreviousAssemblies;
-
-			if (EnableShellIntegrationCommand)
-			{
-				AddRemoveShellIntegrationCommand = new DelegateCommand<object>(AddRemoveShellIntegration);
-			}
 		}
 
 		/// <summary>
 		/// Allow multiple instances.
 		/// </summary>
 		public bool AllowMultipleInstances {
-			get { return allowMultipleInstances; }
-			set {
-				if (allowMultipleInstances != value)
-				{
-					allowMultipleInstances = value;
-					OnPropertyChanged();
-				}
-			}
+			get => allowMultipleInstances;
+			set => SetProperty(ref allowMultipleInstances, value);
 		}
 
 		/// <summary>
 		/// Load assemblies that were loaded in the previous instance
 		/// </summary>
 		public bool LoadPreviousAssemblies {
-			get { return loadPreviousAssemblies; }
-			set {
-				if (loadPreviousAssemblies != value)
-				{
-					loadPreviousAssemblies = value;
-					OnPropertyChanged();
-				}
-			}
+			get => loadPreviousAssemblies;
+			set => SetProperty(ref loadPreviousAssemblies, value);
 		}
 
-		public ICommand AddRemoveShellIntegrationCommand { get; }
-		public bool EnableShellIntegrationCommand => AppEnvironment.IsWindows;
+		public ICommand AddRemoveShellIntegrationCommand => new DelegateCommand(() => AppEnvironment.IsWindows, AddRemoveShellIntegration);
 
 		const string rootPath = @"Software\Classes\{0}\shell";
 		const string fullPath = @"Software\Classes\{0}\shell\Open with ILSpy\command";
 
-		private void AddRemoveShellIntegration(object obj)
+		private void AddRemoveShellIntegration()
 		{
-			string commandLine = CommandLineTools.ArgumentArrayToCommandLine(Path.ChangeExtension(Assembly.GetEntryAssembly().Location, ".exe")) + " \"%L\"";
+			string commandLine = CommandLineTools.ArgumentArrayToCommandLine(Path.ChangeExtension(Assembly.GetEntryAssembly()?.Location, ".exe")) + " \"%L\"";
 			if (RegistryEntriesExist())
 			{
 				if (MessageBox.Show(string.Format(Properties.Resources.RemoveShellIntegrationMessage, commandLine), "ILSpy", MessageBoxButton.YesNo, MessageBoxImage.Question) == MessageBoxResult.Yes)
 				{
-					Registry.CurrentUser.CreateSubKey(string.Format(rootPath, "dllfile")).DeleteSubKeyTree("Open with ILSpy");
-					Registry.CurrentUser.CreateSubKey(string.Format(rootPath, "exefile")).DeleteSubKeyTree("Open with ILSpy");
+					Registry.CurrentUser
+						.CreateSubKey(string.Format(rootPath, "dllfile"))?
+						.DeleteSubKeyTree("Open with ILSpy");
+					Registry.CurrentUser
+						.CreateSubKey(string.Format(rootPath, "exefile"))?
+						.DeleteSubKeyTree("Open with ILSpy");
 				}
 			}
 			else
 			{
 				if (MessageBox.Show(string.Format(Properties.Resources.AddShellIntegrationMessage, commandLine), "ILSpy", MessageBoxButton.YesNo, MessageBoxImage.Question) == MessageBoxResult.Yes)
 				{
-					Registry.CurrentUser.CreateSubKey(string.Format(fullPath, "dllfile"))?
+					Registry.CurrentUser
+						.CreateSubKey(string.Format(fullPath, "dllfile"))?
 						.SetValue("", commandLine);
-					Registry.CurrentUser.CreateSubKey(string.Format(fullPath, "exefile"))?
+					Registry.CurrentUser
+						.CreateSubKey(string.Format(fullPath, "exefile"))?
 						.SetValue("", commandLine);
 				}
 			}
@@ -116,21 +105,5 @@ namespace ICSharpCode.ILSpy.Options
 				return RegistryEntriesExist() ? Properties.Resources.RemoveShellIntegration : Properties.Resources.AddShellIntegration;
 			}
 		}
-
-		#region INotifyPropertyChanged Implementation
-
-		public event PropertyChangedEventHandler PropertyChanged;
-
-		protected virtual void OnPropertyChanged(PropertyChangedEventArgs e)
-		{
-			PropertyChanged?.Invoke(this, e);
-		}
-
-		protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
-		{
-			OnPropertyChanged(new PropertyChangedEventArgs(propertyName));
-		}
-
-		#endregion
 	}
 }
diff --git a/ILSpy/Options/OptionsDialog.xaml.cs b/ILSpy/Options/OptionsDialog.xaml.cs
index 191f41ef7..022219374 100644
--- a/ILSpy/Options/OptionsDialog.xaml.cs
+++ b/ILSpy/Options/OptionsDialog.xaml.cs
@@ -20,9 +20,6 @@ using System;
 using System.ComponentModel.Composition;
 using System.Linq;
 using System.Windows;
-using System.Windows.Controls;
-using System.Windows.Documents;
-using System.Windows.Media;
 using System.Xml.Linq;
 
 using ICSharpCode.ILSpy.Properties;
@@ -41,6 +38,7 @@ namespace ICSharpCode.ILSpy.Options
 		}
 
 		public string Header { get; }
+
 		public UIElement Content { get; }
 	}
 
@@ -56,7 +54,7 @@ namespace ICSharpCode.ILSpy.Options
 			InitializeComponent();
 			var ep = App.ExportProvider;
 			this.optionPages = ep.GetExports<UIElement, IOptionsMetadata>("OptionPages").ToArray();
-			ILSpySettings settings = ILSpySettings.Load();
+			ILSpySettings settings = SettingsService.Instance.SpySettings;
 			foreach (var optionPage in optionPages.OrderBy(p => p.Metadata.Order))
 			{
 				var tabItem = new TabItemViewModel(Util.ResourceHelper.GetString(optionPage.Metadata.Title), optionPage.Value);
@@ -71,8 +69,8 @@ namespace ICSharpCode.ILSpy.Options
 
 		void OKButton_Click(object sender, RoutedEventArgs e)
 		{
-			ILSpySettings.Update(
-				delegate (XElement root) {
+			SettingsService.Instance.SpySettings.Update(
+				root => {
 					foreach (var optionPage in optionPages)
 					{
 						IOptionPage page = optionPage.Value as IOptionPage;
@@ -126,8 +124,9 @@ namespace ICSharpCode.ILSpy.Options
 	{
 		public override void Execute(object parameter)
 		{
-			OptionsDialog dlg = new OptionsDialog();
-			dlg.Owner = MainWindow.Instance;
+			OptionsDialog dlg = new() {
+				Owner = MainWindow.Instance
+			};
 			if (dlg.ShowDialog() == true)
 			{
 				new RefreshCommand().Execute(parameter);
diff --git a/ILSpy/SessionSettings.cs b/ILSpy/SessionSettings.cs
index 414d644cb..7749e516b 100644
--- a/ILSpy/SessionSettings.cs
+++ b/ILSpy/SessionSettings.cs
@@ -62,8 +62,8 @@ namespace ICSharpCode.ILSpy
 			this.WindowBounds = FromString((string)doc.Element("WindowBounds"), DefaultWindowBounds);
 			this.SelectedSearchMode = FromString((string)doc.Element("SelectedSearchMode"), SearchMode.TypeAndMember);
 			this.Theme = FromString((string)doc.Element(nameof(Theme)), ThemeManager.Current.DefaultTheme);
-			string currentCulture = (string)doc.Element(nameof(CurrentCulture));
-			this.CurrentCulture = string.IsNullOrEmpty(currentCulture) ? null : currentCulture;
+			var culture = (string)doc.Element(nameof(CurrentCulture));
+			this.CurrentCulture = string.IsNullOrEmpty(culture) ? null : culture;
 
 			this.DockLayout = new DockLayoutSettings(doc.Element("DockLayout"));
 		}
@@ -161,7 +161,7 @@ namespace ICSharpCode.ILSpy
 		public void Save()
 		{
 			var doc = ToXml();
-			ILSpySettings.SaveSettings(doc);
+			SettingsService.Instance.SpySettings.SaveSettings(doc);
 		}
 
 		static Regex regex = new Regex("\\\\x(?<num>[0-9A-f]{4})");
diff --git a/ILSpy/Updates/UpdateSettings.cs b/ILSpy/Updates/UpdateSettings.cs
index 777f23eee..653f078a9 100644
--- a/ILSpy/Updates/UpdateSettings.cs
+++ b/ILSpy/Updates/UpdateSettings.cs
@@ -75,7 +75,7 @@ namespace ICSharpCode.ILSpy.Updates
 			updateSettings.Add(new XElement("AutomaticUpdateCheckEnabled", automaticUpdateCheckEnabled));
 			if (lastSuccessfulUpdateCheck != null)
 				updateSettings.Add(new XElement("LastSuccessfulUpdateCheck", lastSuccessfulUpdateCheck));
-			ILSpySettings.SaveSettings(updateSettings);
+			SettingsService.Instance.SpySettings.SaveSettings(updateSettings);
 		}
 
 		public event PropertyChangedEventHandler PropertyChanged;
diff --git a/ILSpy/Util/SettingsService.cs b/ILSpy/Util/SettingsService.cs
index e843c85e3..8e8d2e8a6 100644
--- a/ILSpy/Util/SettingsService.cs
+++ b/ILSpy/Util/SettingsService.cs
@@ -18,6 +18,7 @@ namespace ICSharpCode.ILSpy.Util
 			SessionSettings = new(SpySettings);
 			DecompilerSettings = DecompilerSettingsPanel.LoadDecompilerSettings(SpySettings);
 			DisplaySettings = DisplaySettingsPanel.LoadDisplaySettings(SpySettings, SessionSettings);
+			MiscSettings = MiscSettings.Load(SpySettings);
 			AssemblyListManager = new(SpySettings) {
 				ApplyWinRTProjections = DecompilerSettings.ApplyWindowsRuntimeProjections,
 				UseDebugSymbols = DecompilerSettings.UseDebugSymbols
@@ -32,11 +33,28 @@ namespace ICSharpCode.ILSpy.Util
 
 		public DisplaySettings DisplaySettings { get; }
 
+		public MiscSettings MiscSettings { get; set; }
+
 		public AssemblyListManager AssemblyListManager { get; }
 
 		public DecompilationOptions CreateDecompilationOptions(TabPageModel tabPage)
 		{
 			return new(SessionSettings.LanguageSettings.LanguageVersion, DecompilerSettings, DisplaySettings) { Progress = tabPage.Content as IProgress<DecompilationProgress> };
 		}
+
+		public AssemblyList LoadInitialAssemblyList()
+		{
+			var loadPreviousAssemblies = MiscSettings.LoadPreviousAssemblies;
+
+			if (loadPreviousAssemblies)
+			{
+				return AssemblyListManager.LoadList(SessionSettings.ActiveAssemblyList);
+			}
+			else
+			{
+				AssemblyListManager.ClearAll();
+				return AssemblyListManager.CreateList(AssemblyListManager.DefaultListName);
+			}
+		}
 	}
 }