Consolidate all options/settings to use a consistent WFP MVVM pattern.

ICSharpCode.ILSpyX/AssemblyListManager.cs

@@ -59,9 +59,9 @@ namespace ICSharpCode.ILSpyX
 
 		public bool UseDebugSymbols { get; set; }
 
-		public ObservableCollection<string> AssemblyLists { get; } = new ObservableCollection<string>();
+		public ObservableCollection<string> AssemblyLists { get; } = [];
 
-		public FileLoaderRegistry LoaderRegistry { get; } = new FileLoaderRegistry();
+		public FileLoaderRegistry LoaderRegistry { get; } = new();
 
 		/// <summary>
 		/// Loads an assembly list from the ILSpySettings.

ICSharpCode.ILSpyX/Settings/ILSpySettings.cs

@@ -123,11 +123,6 @@ namespace ICSharpCode.ILSpyX.Settings
 			}
 		}
 
-		void ISettingsProvider.Update(Action<XElement> action)
-		{
-			Update(action);
-		}
-
 		static string GetConfigFile()
 		{
 			if (null != SettingsFilePathProvider)
@@ -148,17 +143,16 @@ namespace ICSharpCode.ILSpyX.Settings
 
 			public MutexProtector(string name)
 			{
-				bool createdNew;
-				this.mutex = new Mutex(true, name, out createdNew);
-				if (!createdNew)
+				this.mutex = new Mutex(true, name, out bool createdNew);
+				if (createdNew)
+					return;
+
+				try
+				{
+					mutex.WaitOne();
+				}
+				catch (AbandonedMutexException)
 				{
-					try
-					{
-						mutex.WaitOne();
-					}
-					catch (AbandonedMutexException)
-					{
-					}
 				}
 			}
 

ICSharpCode.ILSpyX/Settings/IMiscSettings.cs

@@ -1,42 +0,0 @@
-// Copyright (c) 2022 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.
-
-using System;
-using System.Xml.Linq;
-
-namespace ICSharpCode.ILSpyX.Settings
-{
-	public interface IMiscSettings
-	{
-		public bool AllowMultipleInstances { get; set; }
-		public bool LoadPreviousAssemblies { get; set; }
-
-		public static void Save(XElement root, IMiscSettings miscSettings)
-		{
-			var section = new XElement("MiscSettings");
-			section.SetAttributeValue(nameof(miscSettings.AllowMultipleInstances), miscSettings.AllowMultipleInstances);
-			section.SetAttributeValue(nameof(miscSettings.LoadPreviousAssemblies), miscSettings.LoadPreviousAssemblies);
-
-			XElement? existingElement = root.Element("MiscSettings");
-			if (existingElement != null)
-				existingElement.ReplaceWith(section);
-			else
-				root.Add(section);
-		}
-	}
-}

ICSharpCode.ILSpyX/Settings/ISettingsFilePathProvider.cs

@@ -16,8 +16,6 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
-using System;
-
 namespace ICSharpCode.ILSpyX.Settings
 {
 	public interface ISettingsFilePathProvider

ICSharpCode.ILSpyX/Settings/ISettingsProvider.cs

@@ -17,9 +17,6 @@
 // DEALINGS IN THE SOFTWARE.
 
 using System;
-using System.ComponentModel;
-using System.Linq;
-using System.Reflection;
 using System.Xml.Linq;
 
 namespace ICSharpCode.ILSpyX.Settings
@@ -30,37 +27,6 @@ namespace ICSharpCode.ILSpyX.Settings
 
 		void Update(Action<XElement> action);
 
-		public static Decompiler.DecompilerSettings LoadDecompilerSettings(ISettingsProvider settingsProvider)
-		{
-			XElement e = settingsProvider["DecompilerSettings"];
-			var newSettings = new Decompiler.DecompilerSettings();
-			var properties = typeof(Decompiler.DecompilerSettings).GetProperties()
-				.Where(p => p.GetCustomAttribute<BrowsableAttribute>()?.Browsable != false);
-			foreach (var p in properties)
-			{
-				var value = (bool?)e.Attribute(p.Name);
-				if (value.HasValue)
-					p.SetValue(newSettings, value.Value);
-			}
-			return newSettings;
-		}
-
-		public static void SaveDecompilerSettings(XElement root, Decompiler.DecompilerSettings newSettings)
-		{
-			var properties = typeof(Decompiler.DecompilerSettings).GetProperties()
-				.Where(p => p.GetCustomAttribute<BrowsableAttribute>()?.Browsable != false);
-
-			XElement section = new XElement("DecompilerSettings");
-			foreach (var p in properties)
-			{
-				section.SetAttributeValue(p.Name, p.GetValue(newSettings));
-			}
-
-			XElement? existingElement = root.Element("DecompilerSettings");
-			if (existingElement != null)
-				existingElement.ReplaceWith(section);
-			else
-				root.Add(section);
-		}
+		void SaveSettings(XElement section);
 	}
 }

ICSharpCode.ILSpyX/Settings/ISettingsSection.cs

@@ -1,32 +0,0 @@
-// Copyright (c) 2022 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.
-
-using System;
-
-namespace ICSharpCode.ILSpyX.Settings
-{
-	public interface ISettingsSection<TSelf>
-	{
-		// This should be abstract, but that needs C# 11.0 (see IParseable<TSelf>)
-		// Keep it to be enabled in the future
-		public static TSelf Load(ISettingsProvider settingsProvider)
-		{
-			throw new NotImplementedException();
-		}
-	}
-}

ILSpy.ReadyToRun/ReadyToRunDisassembler.cs

@@ -51,11 +51,13 @@ namespace ICSharpCode.ILSpy.ReadyToRun
 			ReadyToRunMethod readyToRunMethod = runtimeFunction.Method;
 			WriteCommentLine(readyToRunMethod.SignatureString);
 
-			if (ReadyToRunOptions.GetIsShowGCInfo(null))
+			var options = SettingsService.Instance.GetSettings<ReadyToRunOptions>();
+
+			if (options.IsShowGCInfo)
 			{
 				if (readyToRunMethod.GcInfo != null)
 				{
-					string[] lines = readyToRunMethod.GcInfo.ToString().Split(Environment.NewLine);
+					string[] lines = readyToRunMethod.GcInfo.ToString()?.Split(Environment.NewLine) ?? [];
 					WriteCommentLine("GC info:");
 					foreach (string line in lines)
 					{
@@ -69,12 +71,12 @@ namespace ICSharpCode.ILSpy.ReadyToRun
 			}
 
 			Dictionary<ulong, UnwindCode> unwindInfo = null;
-			if (ReadyToRunOptions.GetIsShowUnwindInfo(null) && bitness == 64)
+			if (options.IsShowUnwindInfo && bitness == 64)
 			{
 				unwindInfo = WriteUnwindInfo();
 			}
 
-			bool isShowDebugInfo = ReadyToRunOptions.GetIsShowDebugInfo(null);
+			bool isShowDebugInfo = options.IsShowDebugInfo;
 			DebugInfoHelper debugInfo = null;
 			if (isShowDebugInfo)
 			{
@@ -98,7 +100,7 @@ namespace ICSharpCode.ILSpy.ReadyToRun
 				decoder.Decode(out instructions.AllocUninitializedElement());
 			}
 
-			string disassemblyFormat = ReadyToRunOptions.GetDisassemblyFormat(null);
+			string disassemblyFormat = options.DisassemblyFormat;
 			Formatter formatter = null;
 			if (disassemblyFormat.Equals(ReadyToRunOptions.intel))
 			{
@@ -145,7 +147,7 @@ namespace ICSharpCode.ILSpy.ReadyToRun
 						}
 					}
 				}
-				if (ReadyToRunOptions.GetIsShowGCInfo(null))
+				if (options.IsShowGCInfo)
 				{
 					DecorateGCInfo(instr, baseInstrIP, readyToRunMethod.GcInfo);
 				}

ILSpy.ReadyToRun/ReadyToRunOptionPage.xaml

@@ -1,7 +1,11 @@
 <UserControl x:Class="ICSharpCode.ILSpy.ReadyToRun.ReadyToRunOptionPage"
 	xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 	xmlns:properties="clr-namespace:ILSpy.ReadyToRun.Properties"
-	xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+	xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+	xmlns:d="http://schemas.microsoft.com/expression/blend/2008" d:DesignHeight="500" d:DesignWidth="500" mc:Ignorable="d"
+	xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+	xmlns:readyToRun="clr-namespace:ICSharpCode.ILSpy.ReadyToRun"
+	d:DataContext="{d:DesignInstance readyToRun:ReadyToRunOptionsViewModel}">
 	<Grid>
 		<Grid.ColumnDefinitions>
 			<ColumnDefinition />
@@ -14,12 +18,12 @@
 			<RowDefinition Height="Auto" />
 		</Grid.RowDefinitions>
 		<TextBlock Margin="3" Text="{x:Static properties:Resources.DisassemblyFormat}" />
-		<ComboBox Grid.Column="1" Margin="3" ItemsSource="{Binding DisassemblyFormats}" SelectedItem="{Binding DisassemblyFormat}" />
-		<TextBlock Grid.Row="1" Margin="3" Text="{x:Static properties:Resources.ShowStackUnwindInfo}"/>
-		<CheckBox Grid.Row="1" Grid.Column="1" Margin="3" IsChecked="{Binding IsShowUnwindInfo}" />
+		<ComboBox Grid.Row="0" Grid.Column="1" Margin="3" ItemsSource="{Binding Options.DisassemblyFormats}" SelectedItem="{Binding Options.DisassemblyFormat}" />
+		<TextBlock Grid.Row="1" Grid.Column="0"  Margin="3" Text="{x:Static properties:Resources.ShowStackUnwindInfo}"/>
+		<CheckBox Grid.Row="1" Grid.Column="1" Margin="3" IsChecked="{Binding Options.IsShowUnwindInfo}" />
 		<TextBlock Grid.Row="2" Margin="3" Text="{x:Static properties:Resources.ShowDebugInfo}"/>
-		<CheckBox Grid.Row="2" Grid.Column="1" Margin="3" IsChecked="{Binding IsShowDebugInfo}" />
+		<CheckBox Grid.Row="2" Grid.Column="1" Margin="3" IsChecked="{Binding Options.IsShowDebugInfo}" />
 		<TextBlock Grid.Row="3" Margin="3" Text="{x:Static properties:Resources.ShowGCInfo}"/>
-		<CheckBox Grid.Row="3" Grid.Column="1" Margin="3" IsChecked="{Binding IsShowGCInfo}" />
+		<CheckBox Grid.Row="3" Grid.Column="1" Margin="3" IsChecked="{Binding Options.IsShowGCInfo}" />
 	</Grid>
 </UserControl>

ILSpy.ReadyToRun/ReadyToRunOptionPage.xaml.cs

@@ -16,114 +16,47 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
-using System.ComponentModel;
 using System.ComponentModel.Composition;
-using System.Windows.Controls;
-using System.Xml.Linq;
 
 using ICSharpCode.ILSpy.Options;
-using ICSharpCode.ILSpyX.Settings;
+using ICSharpCode.ILSpy.Util;
+
+using TomsToolbox.Wpf;
+using TomsToolbox.Wpf.Composition.Mef;
 
 namespace ICSharpCode.ILSpy.ReadyToRun
 {
-	[ExportOptionPage(Order = 40)]
+	[DataTemplate(typeof(ReadyToRunOptionsViewModel))]
 	[PartCreationPolicy(CreationPolicy.NonShared)]
-	partial class ReadyToRunOptionPage : UserControl, IOptionPage
+	partial class ReadyToRunOptionPage
 	{
 		public ReadyToRunOptionPage()
 		{
 			InitializeComponent();
 		}
-
-		public string Title => global::ILSpy.ReadyToRun.Properties.Resources.ReadyToRun;
-
-		public void Load(ILSpySettings spySettings)
-		{
-			Options s = new Options();
-			s.DisassemblyFormat = ReadyToRunOptions.GetDisassemblyFormat(spySettings);
-			s.IsShowUnwindInfo = ReadyToRunOptions.GetIsShowUnwindInfo(spySettings);
-			s.IsShowDebugInfo = ReadyToRunOptions.GetIsShowDebugInfo(spySettings);
-			s.IsShowGCInfo = ReadyToRunOptions.GetIsShowGCInfo(spySettings);
-
-			this.DataContext = s;
-		}
-
-		public void LoadDefaults()
-		{
-			this.DataContext = new Options();
-		}
-
-		public void Save(XElement root)
-		{
-			Options s = (Options)this.DataContext;
-			ReadyToRunOptions.SetDisassemblyOptions(root, s.DisassemblyFormat, s.IsShowUnwindInfo, s.IsShowDebugInfo, s.IsShowGCInfo);
-		}
 	}
 
-	internal class Options : INotifyPropertyChanged
+	[ExportOptionPage(Order = 40)]
+	[PartCreationPolicy(CreationPolicy.NonShared)]
+	class ReadyToRunOptionsViewModel : ObservableObject, IOptionPage
 	{
-		public string[] DisassemblyFormats {
-			get {
-				return ReadyToRunOptions.disassemblyFormats;
-			}
-		}
-
-		private bool isShowUnwindInfo;
-		public bool IsShowUnwindInfo {
-			get {
-				return isShowUnwindInfo;
-			}
-			set {
-				isShowUnwindInfo = value;
-				OnPropertyChanged(nameof(IsShowUnwindInfo));
-			}
-		}
-
-		private bool isShowDebugInfo;
+		private ReadyToRunOptions options;
 
-		public bool IsShowDebugInfo {
-			get {
-				return isShowDebugInfo;
-			}
-			set {
-				isShowDebugInfo = value;
-				OnPropertyChanged(nameof(IsShowDebugInfo));
-			}
+		public ReadyToRunOptions Options {
+			get => options;
+			set => SetProperty(ref options, value);
 		}
 
-		private bool isShowGCInfo;
-
-		public bool IsShowGCInfo {
-			get {
-				return isShowGCInfo;
-			}
-			set {
-				isShowGCInfo = value;
-				OnPropertyChanged(nameof(IsShowGCInfo));
-			}
-		}
-
-		private string disassemblyFormat;
+		public string Title => global::ILSpy.ReadyToRun.Properties.Resources.ReadyToRun;
 
-		public string DisassemblyFormat {
-			get { return disassemblyFormat; }
-			set {
-				if (disassemblyFormat != value)
-				{
-					disassemblyFormat = value;
-					OnPropertyChanged(nameof(DisassemblyFormat));
-				}
-			}
+		public void Load(SettingsSnapshot snapshot)
+		{
+			Options = snapshot.GetSettings<ReadyToRunOptions>();
 		}
 
-		public event PropertyChangedEventHandler PropertyChanged;
-
-		protected virtual void OnPropertyChanged(string propertyName)
+		public void LoadDefaults()
 		{
-			if (PropertyChanged != null)
-			{
-				PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
-			}
+			Options.LoadFromSection(new("empty"));
 		}
 	}
 }

ILSpy.ReadyToRun/ReadyToRunOptions.cs

@@ -19,102 +19,72 @@
 using System.Xml.Linq;
 
 using ICSharpCode.ILSpy.Util;
-using ICSharpCode.ILSpyX;
-using ICSharpCode.ILSpyX.Settings;
+
+using TomsToolbox.Wpf;
 
 namespace ICSharpCode.ILSpy.ReadyToRun
 {
-	internal class ReadyToRunOptions
+	internal partial class ReadyToRunOptions : ObservableObject, ISettingsSection
 	{
 		private static readonly XNamespace ns = "http://www.ilspy.net/ready-to-run";
 
 		internal static string intel = "Intel";
 		internal static string gas = "AT & T";
-		internal static string[] disassemblyFormats = new string[] { intel, gas };
-
-		public static string GetDisassemblyFormat(ILSpySettings settings)
-		{
-			settings ??= SettingsService.Instance.SpySettings;
+		internal static string[] disassemblyFormats = [intel, gas];
 
-			XElement e = settings[ns + "ReadyToRunOptions"];
-			XAttribute a = e.Attribute("DisassemblyFormat");
-			if (a == null)
-			{
-				return ReadyToRunOptions.intel;
-			}
-			else
-			{
-				return (string)a;
+		public string[] DisassemblyFormats {
+			get {
+				return disassemblyFormats;
 			}
 		}
 
-		public static bool GetIsShowUnwindInfo(ILSpySettings settings)
-		{
-			settings ??= SettingsService.Instance.SpySettings;
-
-			XElement e = settings[ns + "ReadyToRunOptions"];
-			XAttribute a = e.Attribute("IsShowUnwindInfo");
-
-			if (a == null)
-			{
-				return false;
-			}
-			else
-			{
-				return (bool)a;
-			}
+		private bool isShowUnwindInfo;
+		public bool IsShowUnwindInfo {
+			get => isShowUnwindInfo;
+			set => SetProperty(ref isShowUnwindInfo, value);
 		}
 
-		public static bool GetIsShowDebugInfo(ILSpySettings settings)
-		{
-			settings ??= SettingsService.Instance.SpySettings;
+		private bool isShowDebugInfo;
+		public bool IsShowDebugInfo {
+			get => isShowDebugInfo;
+			set => SetProperty(ref isShowDebugInfo, value);
+		}
 
-			XElement e = settings[ns + "ReadyToRunOptions"];
-			XAttribute a = e.Attribute("IsShowDebugInfo");
+		private bool isShowGCInfo;
+		public bool IsShowGCInfo {
+			get => isShowGCInfo;
+			set => SetProperty(ref isShowGCInfo, value);
+		}
 
-			if (a == null)
-			{
-				return true;
-			}
-			else
-			{
-				return (bool)a;
-			}
+		private string disassemblyFormat;
+		public string DisassemblyFormat {
+			get => disassemblyFormat;
+			set => SetProperty(ref disassemblyFormat, value);
 		}
 
-		public static bool GetIsShowGCInfo(ILSpySettings settings)
+		public XName SectionName { get; } = ns + "ReadyToRunOptions";
+
+		public void LoadFromSection(XElement e)
 		{
-			settings ??= SettingsService.Instance.SpySettings;
+			XAttribute format = e.Attribute("DisassemblyFormat");
+			DisassemblyFormat = format == null ? intel : (string)format;
 
-			XElement e = settings[ns + "ReadyToRunOptions"];
-			XAttribute a = e.Attribute("IsShowGCInfo");
+			XAttribute unwind = e.Attribute("IsShowUnwindInfo");
+			IsShowUnwindInfo = unwind != null && (bool)unwind;
 
-			if (a == null)
-			{
-				return false;
-			}
-			else
-			{
-				return (bool)a;
-			}
+			XAttribute debug = e.Attribute("IsShowDebugInfo");
+			IsShowDebugInfo = debug == null || (bool)debug;
+
+			XAttribute showGc = e.Attribute("IsShowGCInfo");
+			IsShowGCInfo = showGc != null && (bool)showGc;
 		}
 
-		public static void SetDisassemblyOptions(XElement root, string disassemblyFormat, bool isShowUnwindInfo, bool isShowDebugInfo, bool isShowGCInfo)
+		public void SaveToSection(XElement section)
 		{
-			XElement section = new XElement(ns + "ReadyToRunOptions");
 			section.SetAttributeValue("DisassemblyFormat", disassemblyFormat);
 			section.SetAttributeValue("IsShowUnwindInfo", isShowUnwindInfo);
 			section.SetAttributeValue("IsShowDebugInfo", isShowDebugInfo);
 			section.SetAttributeValue("IsShowGCInfo", isShowGCInfo);
-			XElement existingElement = root.Element(ns + "ReadyToRunOptions");
-			if (existingElement != null)
-			{
-				existingElement.ReplaceWith(section);
-			}
-			else
-			{
-				root.Add(section);
-			}
 		}
 	}
 }

ILSpy/App.xaml.cs

@@ -32,9 +32,7 @@ using System.Windows.Threading;
 
 using ICSharpCode.ILSpy.AppEnv;
 using ICSharpCode.ILSpy.AssemblyTree;
-using ICSharpCode.ILSpy.Options;
 using ICSharpCode.ILSpyX.Analyzers;
-using ICSharpCode.ILSpyX.Settings;
 
 using Medo.Application;
 
@@ -66,11 +64,17 @@ namespace ICSharpCode.ILSpy
 
 		public App()
 		{
-			ILSpySettings.SettingsFilePathProvider = new ILSpySettingsFilePathProvider();
-
 			var cmdArgs = Environment.GetCommandLineArgs().Skip(1);
 			CommandLineArguments = CommandLineArguments.Create(cmdArgs);
 
+			bool forceSingleInstance = (CommandLineArguments.SingleInstance ?? true)
+									   && !SettingsService.Instance.MiscSettings.AllowMultipleInstances;
+			if (forceSingleInstance)
+			{
+				SingleInstance.Attach();  // will auto-exit for second instance
+				SingleInstance.NewInstanceDetected += SingleInstance_NewInstanceDetected;
+			}
+
 			SharpTreeNode.SetImagesProvider(new WpfWindowsTreeNodeImagesProvider());
 
 			InitializeComponent();
@@ -85,14 +89,6 @@ 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.

ILSpy/AssemblyTree/AssemblyListPaneModel.cs

@@ -77,30 +77,40 @@ namespace ICSharpCode.ILSpy.AssemblyTree
 			ShortcutKey = new KeyGesture(Key.F6);
 
 			MessageBus<NavigateToReferenceEventArgs>.Subscribers += JumpToReference;
-			MessageBus<SessionSettingsChangedEventArgs>.Subscribers += (sender, e) => SessionSettings_PropertyChanged(sender, e);
-			MessageBus<LanguageSettingsChangedEventArgs>.Subscribers += (sender, e) => LanguageSettings_PropertyChanged(sender, e);
+			MessageBus<SettingsChangedEventArgs>.Subscribers += (sender, e) => Settings_PropertyChanged(sender, e);
 
 			var selectionChangeThrottle = new DispatcherThrottle(DispatcherPriority.Background, TreeView_SelectionChanged);
 			SelectedItems.CollectionChanged += (_, _) => selectionChangeThrottle.Tick();
 		}
 
-		private void SessionSettings_PropertyChanged(object sender, PropertyChangedEventArgs e)
+		private void Settings_PropertyChanged(object sender, PropertyChangedEventArgs e)
 		{
-			var sessionSettings = SettingsService.Instance.SessionSettings;
-
-			switch (e.PropertyName)
+			if (sender is SessionSettings sessionSettings)
 			{
-				case nameof(SessionSettings.ActiveAssemblyList):
-					ShowAssemblyList(sessionSettings.ActiveAssemblyList);
-					break;
-				case nameof(SessionSettings.Theme):
-					// update syntax highlighting and force reload (AvalonEdit does not automatically refresh on highlighting change)
-					DecompilerTextView.RegisterHighlighting();
-					DecompileSelectedNodes(DockWorkspace.Instance.ActiveTabPage.GetState() as DecompilerTextViewState);
-					break;
-				case nameof(SessionSettings.CurrentCulture):
-					MessageBox.Show(Properties.Resources.SettingsChangeRestartRequired, "ILSpy");
-					break;
+				switch (e.PropertyName)
+				{
+					case nameof(SessionSettings.ActiveAssemblyList):
+						ShowAssemblyList(sessionSettings.ActiveAssemblyList);
+						break;
+					case nameof(SessionSettings.Theme):
+						// update syntax highlighting and force reload (AvalonEdit does not automatically refresh on highlighting change)
+						DecompilerTextView.RegisterHighlighting();
+						DecompileSelectedNodes(
+							DockWorkspace.Instance.ActiveTabPage.GetState() as DecompilerTextViewState);
+						break;
+					case nameof(SessionSettings.CurrentCulture):
+						MessageBox.Show(Properties.Resources.SettingsChangeRestartRequired, "ILSpy");
+						break;
+				}
+			}
+			else if (sender is LanguageSettings)
+			{
+				switch (e.PropertyName)
+				{
+					case nameof(LanguageSettings.Language) or nameof(LanguageSettings.LanguageVersion):
+						DecompileSelectedNodes(recordHistory: false);
+						break;
+				}
 			}
 		}
 
@@ -136,7 +146,7 @@ namespace ICSharpCode.ILSpy.AssemblyTree
 		/// Called on startup or when passed arguments via WndProc from a second instance.
 		/// In the format case, spySettings is non-null; in the latter it is null.
 		/// </summary>
-		public void HandleCommandLineArgumentsAfterShowList(CommandLineArguments args, ILSpySettings spySettings = null)
+		public void HandleCommandLineArgumentsAfterShowList(CommandLineArguments args, ISettingsProvider spySettings = null)
 		{
 			var sessionSettings = SettingsService.Instance.SessionSettings;
 
@@ -172,7 +182,7 @@ namespace ICSharpCode.ILSpy.AssemblyTree
 			});
 		}
 
-		public async void NavigateOnLaunch(string navigateTo, string[] activeTreeViewPath, ILSpySettings spySettings, List<LoadedAssembly> relevantAssemblies)
+		public async void NavigateOnLaunch(string navigateTo, string[] activeTreeViewPath, ISettingsProvider spySettings, List<LoadedAssembly> relevantAssemblies)
 		{
 			var initialSelection = SelectedItem;
 			if (navigateTo != null)
@@ -458,14 +468,6 @@ namespace ICSharpCode.ILSpy.AssemblyTree
 				AssemblyList.OpenAssembly(asm.Location);
 		}
 
-		void LanguageSettings_PropertyChanged(object sender, PropertyChangedEventArgs e)
-		{
-			if (e.PropertyName is nameof(LanguageSettings.Language) or nameof(LanguageSettings.LanguageVersion))
-			{
-				DecompileSelectedNodes(recordHistory: false);
-			}
-		}
-
 		public AssemblyTreeNode FindAssemblyNode(LoadedAssembly asm)
 		{
 			return assemblyListTreeNode.FindAssemblyNode(asm);

ILSpy/Commands/CheckForUpdatesCommand.cs

@@ -20,7 +20,6 @@
 using System.ComponentModel.Composition;
 
 using ICSharpCode.ILSpy.Properties;
-using ICSharpCode.ILSpyX.Settings;
 
 namespace ICSharpCode.ILSpy
 {

ILSpy/Commands/SetThemeCommand.cs

@@ -6,7 +6,14 @@ namespace ICSharpCode.ILSpy.Commands
 		public override void Execute(object parameter)
 		{
 			if (parameter is string theme)
-				SettingsService.Instance.SessionSettings.Theme = theme;
+			{
+				var snapshot = SettingsService.Instance.CreateSnapshot();
+				var sessionSettings = snapshot.GetSettings<SessionSettings>();
+
+				sessionSettings.Theme = theme;
+
+				snapshot.Save();
+			}
 		}
 	}
 }

ILSpy/DecompilationOptions.cs

@@ -23,6 +23,8 @@ using ICSharpCode.Decompiler;
 using ICSharpCode.ILSpy.Options;
 using ICSharpCode.ILSpyX;
 
+using DecompilerSettings = ICSharpCode.ILSpy.Options.DecompilerSettings;
+
 namespace ICSharpCode.ILSpy
 {
 	/// <summary>
@@ -87,7 +89,9 @@ namespace ICSharpCode.ILSpy
 		{
 			if (!Enum.TryParse(version?.Version, out Decompiler.CSharp.LanguageVersion languageVersion))
 				languageVersion = Decompiler.CSharp.LanguageVersion.Latest;
+
 			var newSettings = this.DecompilerSettings = settings.Clone();
+
 			newSettings.SetLanguageVersion(languageVersion);
 			newSettings.ExpandMemberDefinitions = displaySettings.ExpandMemberDefinitions;
 			newSettings.ExpandUsingDeclarations = displaySettings.ExpandUsingDeclarations;

ILSpy/LanguageSettings.cs

@@ -25,12 +25,14 @@ using System.Xml.Linq;
 
 using ICSharpCode.ILSpyX;
 
+using TomsToolbox.Wpf;
+
 namespace ICSharpCode.ILSpy
 {
 	/// <summary>
 	/// Represents the filters applied to the tree view.
 	/// </summary>
-	public class LanguageSettings : INotifyPropertyChanged
+	public class LanguageSettings : ObservableObject
 	{
 		/// <summary>
 		/// This dictionary is necessary to remember language versions across language changes. For example, 
@@ -172,20 +174,6 @@ namespace ICSharpCode.ILSpy
 			}
 		}
 
-		public event PropertyChangedEventHandler PropertyChanged;
-
-		protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
-		{
-			if (PropertyChanged != null)
-			{
-				var args = new PropertyChangedEventArgs(propertyName);
-
-				PropertyChanged(this, args);
-				MessageBus.Send(this, new LanguageSettingsChangedEventArgs(args));
-			}
-		}
-
-
 		// This class has been initially called FilterSettings, but then has been Hijacked to store language settings as well.
 		// While the filter settings were some sort of local, the language settings are global. This is a bit of a mess.
 		// There has been a lot of workarounds cloning the FilterSettings to pass them down to the tree nodes, without messing up the global language settings.

ILSpy/MainWindow.xaml

@@ -29,8 +29,6 @@
 			<ContentPresenter Content="{Binding Content}" />
 		</DataTemplate>
 
-		<toms:BindingRelay x:Key="WindowBinding" DataContext="{Binding}" />
-
 	</Window.Resources>
 
 	<b:Interaction.Behaviors>
@@ -93,7 +91,7 @@
 								<Setter.Value>
 									<MultiBinding Converter="{x:Static toms:BinaryOperationConverter.Equality}" Mode="OneWay">
 										<Binding />
-										<Binding Source="{StaticResource WindowBinding}" Path="DataContext.SessionSettings.Theme" />
+										<Binding Path="DataContext.SessionSettings.Theme" RelativeSource="{RelativeSource FindAncestor, AncestorType=Window}"/>
 									</MultiBinding>
 								</Setter.Value>
 							</Setter>

ILSpy/MainWindow.xaml.cs

@@ -34,6 +34,7 @@ using ICSharpCode.ILSpy.AssemblyTree;
 using ICSharpCode.ILSpy.Docking;
 using ICSharpCode.ILSpy.Search;
 using ICSharpCode.ILSpy.TextView;
+using ICSharpCode.ILSpy.Themes;
 using ICSharpCode.ILSpy.TreeNodes;
 using ICSharpCode.ILSpy.Updates;
 using ICSharpCode.ILSpyX.FileLoaders;
@@ -70,6 +71,7 @@ namespace ICSharpCode.ILSpy
 			instance = this;
 
 			var sessionSettings = SettingsService.Instance.SessionSettings;
+			ThemeManager.Current.Theme = sessionSettings.Theme;
 
 			// Make sure Images are initialized on the UI thread.
 			this.Icon = Images.ILSpyIcon;
@@ -165,7 +167,7 @@ namespace ICSharpCode.ILSpy
 		#region Update Check
 		string updateAvailableDownloadUrl;
 
-		public async Task ShowMessageIfUpdatesAvailableAsync(ILSpySettings spySettings, bool forceCheck = false)
+		public async Task ShowMessageIfUpdatesAvailableAsync(ISettingsProvider spySettings, bool forceCheck = false)
 		{
 			string downloadUrl;
 			if (forceCheck)
@@ -337,14 +339,18 @@ namespace ICSharpCode.ILSpy
 		protected override void OnClosing(CancelEventArgs e)
 		{
 			base.OnClosing(e);
-			var sessionSettings = SettingsService.Instance.SessionSettings;
+
+			var snapshot = SettingsService.Instance.CreateSnapshot();
+
+			var sessionSettings = snapshot.GetSettings<SessionSettings>();
 
 			sessionSettings.ActiveAssemblyList = AssemblyTreeModel.AssemblyList.ListName;
 			sessionSettings.ActiveTreeViewPath = AssemblyTreeModel.SelectedPath;
 			sessionSettings.ActiveAutoLoadedAssembly = GetAutoLoadedAssemblyNode(AssemblyTreeModel.SelectedItem);
 			sessionSettings.WindowBounds = this.RestoreBounds;
 			sessionSettings.DockLayout.Serialize(new XmlLayoutSerializer(dockManager));
-			sessionSettings.Save();
+
+			snapshot.Save();
 		}
 
 		private static string GetAutoLoadedAssemblyNode(SharpTreeNode node)

ILSpy/Options/DecompilerSettings.cs

@@ -0,0 +1,48 @@
+using System.ComponentModel;
+
+using ICSharpCode.ILSpyX.Settings;
+using System.Linq;
+using System.Reflection;
+using System.Xml.Linq;
+
+#nullable enable
+
+namespace ICSharpCode.ILSpy.Options
+{
+	public class DecompilerSettings : Decompiler.DecompilerSettings, ISettingsSection
+	{
+		static readonly PropertyInfo[] properties = typeof(Decompiler.DecompilerSettings).GetProperties()
+				.Where(p => p.GetCustomAttribute<BrowsableAttribute>()?.Browsable != false)
+				.ToArray();
+
+		public XName SectionName => "DecompilerSettings";
+
+		public void SaveToSection(XElement section)
+		{
+			foreach (var p in properties)
+			{
+				section.SetAttributeValue(p.Name, p.GetValue(this));
+			}
+		}
+
+		public void LoadFromSection(XElement section)
+		{
+			foreach (var p in properties)
+			{
+				var value = (bool?)section.Attribute(p.Name);
+				if (value.HasValue)
+					p.SetValue(this, value.Value);
+			}
+		}
+
+		public new DecompilerSettings Clone()
+		{
+			var section = new XElement("DecompilerSettings");
+			SaveToSection(section);
+			var newSettings = new DecompilerSettings();
+			newSettings.LoadFromSection(section);
+
+			return newSettings;
+		}
+	}
+}

ILSpy/Options/DecompilerSettingsViewModel.cs

@@ -21,12 +21,9 @@ using System.ComponentModel;
 using System.ComponentModel.Composition;
 using System.Linq;
 using System.Reflection;
-using System.Xml.Linq;
 
-using ICSharpCode.Decompiler;
 using ICSharpCode.ILSpy.Properties;
 using ICSharpCode.ILSpy.TreeNodes;
-using ICSharpCode.ILSpyX.Settings;
 
 using TomsToolbox.Wpf;
 
@@ -36,56 +33,46 @@ namespace ICSharpCode.ILSpy.Options
 	[PartCreationPolicy(CreationPolicy.NonShared)]
 	public sealed class DecompilerSettingsViewModel : ObservableObjectBase, IOptionPage
 	{
-		private DecompilerSettingsGroupViewModel[] settings;
+		private static readonly PropertyInfo[] propertyInfos = typeof(Decompiler.DecompilerSettings).GetProperties()
+			.Where(p => p.GetCustomAttribute<BrowsableAttribute>()?.Browsable != false)
+			.ToArray();
 
 		public string Title => Resources.Decompiler;
 
+		private DecompilerSettingsGroupViewModel[] settings;
 		public DecompilerSettingsGroupViewModel[] Settings {
 			get => settings;
 			set => SetProperty(ref settings, value);
 		}
 
-		public void Load(ILSpySettings spySettings)
+		private DecompilerSettings decompilerSettings;
+
+		public void Load(SettingsSnapshot snapshot)
 		{
-			Load(ISettingsProvider.LoadDecompilerSettings(spySettings));
+			decompilerSettings = snapshot.GetSettings<DecompilerSettings>();
+			LoadSettings();
 		}
 
-		private void Load(DecompilerSettings decompilerSettings)
+		private void LoadSettings()
 		{
-			this.Settings = typeof(Decompiler.DecompilerSettings).GetProperties()
-				.Where(p => p.GetCustomAttribute<BrowsableAttribute>()?.Browsable != false)
-				.Select(p => new DecompilerSettingsItemViewModel(p) { IsEnabled = p.GetValue(decompilerSettings) is true })
+			this.Settings = propertyInfos
+				.Select(p => new DecompilerSettingsItemViewModel(p, decompilerSettings))
 				.OrderBy(item => item.Category, NaturalStringComparer.Instance)
 				.GroupBy(p => p.Category)
 				.Select(g => new DecompilerSettingsGroupViewModel(g.Key, g.OrderBy(i => i.Description).ToArray()))
 				.ToArray();
 		}
 
-		public void Save(XElement root)
-		{
-			var newSettings = ToDecompilerSettings();
-			ISettingsProvider.SaveDecompilerSettings(root, newSettings);
-
-			SettingsService.Instance.DecompilerSettings = newSettings;
-			SettingsService.Instance.AssemblyListManager.ApplyWinRTProjections = newSettings.ApplyWindowsRuntimeProjections;
-			SettingsService.Instance.AssemblyListManager.UseDebugSymbols = newSettings.UseDebugSymbols;
-		}
-
 		public void LoadDefaults()
 		{
-			Load(new DecompilerSettings());
-		}
-
-		private DecompilerSettings ToDecompilerSettings()
-		{
-			var newSettings = new DecompilerSettings();
+			var defaults = new Decompiler.DecompilerSettings();
 
-			foreach (var item in Settings.SelectMany(group => group.Settings))
+			foreach (var propertyInfo in propertyInfos)
 			{
-				item.Property.SetValue(newSettings, item.IsEnabled);
+				propertyInfo.SetValue(decompilerSettings, propertyInfo.GetValue(defaults));
 			}
 
-			return newSettings;
+			LoadSettings();
 		}
 	}
 
@@ -147,15 +134,20 @@ namespace ICSharpCode.ILSpy.Options
 		}
 	}
 
-	public sealed class DecompilerSettingsItemViewModel(PropertyInfo property) : ObservableObjectBase
+	public sealed class DecompilerSettingsItemViewModel(PropertyInfo property, DecompilerSettings decompilerSettings) : ObservableObjectBase
 	{
-		private bool isEnabled;
+		private bool isEnabled = property.GetValue(decompilerSettings) is true;
 
 		public PropertyInfo Property { get; } = property;
 
 		public bool IsEnabled {
 			get => isEnabled;
-			set => SetProperty(ref isEnabled, value);
+			set {
+				if (SetProperty(ref isEnabled, value))
+				{
+					property.SetValue(decompilerSettings, value);
+				}
+			}
 		}
 
 		public string Description { get; set; } = GetResourceString(property.GetCustomAttribute<DescriptionAttribute>()?.Description ?? property.Name);

ILSpy/Options/DisplaySettings.cs

@@ -19,9 +19,6 @@
 using System.Windows.Media;
 using System.Xml.Linq;
 
-using ICSharpCode.ILSpy.Themes;
-using ICSharpCode.ILSpyX.Settings;
-
 using TomsToolbox.Wpf;
 
 namespace ICSharpCode.ILSpy.Options
@@ -29,264 +26,176 @@ namespace ICSharpCode.ILSpy.Options
 	/// <summary>
 	/// Description of DisplaySettings.
 	/// </summary>
-	public class DisplaySettings : ObservableObject
+	public class DisplaySettings : ObservableObject, ISettingsSection
 	{
-		public DisplaySettings()
-		{
-			this.theme = ThemeManager.Current.DefaultTheme;
-			this.selectedFont = new FontFamily("Consolas");
-			this.selectedFontSize = 10.0 * 4 / 3;
-			this.sortResults = true;
-			this.indentationUseTabs = true;
-			this.indentationSize = 4;
-			this.indentationTabSize = 4;
-			this.highlightMatchingBraces = true;
-		}
-
-		string theme;
-
-		public string Theme {
-			get => theme;
-			set => SetProperty(ref theme, value);
-		}
-
 		FontFamily selectedFont;
-
 		public FontFamily SelectedFont {
 			get => selectedFont;
 			set => SetProperty(ref selectedFont, value);
 		}
 
 		double selectedFontSize;
-
 		public double SelectedFontSize {
 			get => selectedFontSize;
 			set => SetProperty(ref selectedFontSize, value);
 		}
 
 		bool showLineNumbers;
-
 		public bool ShowLineNumbers {
 			get => showLineNumbers;
 			set => SetProperty(ref showLineNumbers, value);
 		}
 
 		bool showMetadataTokens;
-
 		public bool ShowMetadataTokens {
 			get => showMetadataTokens;
 			set => SetProperty(ref showMetadataTokens, value);
 		}
 
 		bool showMetadataTokensInBase10;
-
 		public bool ShowMetadataTokensInBase10 {
 			get => showMetadataTokensInBase10;
 			set => SetProperty(ref showMetadataTokensInBase10, value);
 		}
 
 		bool enableWordWrap;
-
 		public bool EnableWordWrap {
 			get => enableWordWrap;
 			set => SetProperty(ref enableWordWrap, value);
 		}
 
 		bool sortResults;
-
 		public bool SortResults {
 			get => sortResults;
 			set => SetProperty(ref sortResults, value);
 		}
 
 		bool foldBraces;
-
 		public bool FoldBraces {
 			get => foldBraces;
 			set => SetProperty(ref foldBraces, value);
 		}
 
 		bool expandMemberDefinitions;
-
 		public bool ExpandMemberDefinitions {
 			get => expandMemberDefinitions;
 			set => SetProperty(ref expandMemberDefinitions, value);
 		}
 
 		bool expandUsingDeclarations;
-
 		public bool ExpandUsingDeclarations {
 			get => expandUsingDeclarations;
 			set => SetProperty(ref expandUsingDeclarations, value);
 		}
 
 		bool showDebugInfo;
-
 		public bool ShowDebugInfo {
 			get => showDebugInfo;
 			set => SetProperty(ref showDebugInfo, value);
 		}
 
 		bool indentationUseTabs;
-
 		public bool IndentationUseTabs {
 			get => indentationUseTabs;
 			set => SetProperty(ref indentationUseTabs, value);
 		}
 
 		int indentationTabSize;
-
 		public int IndentationTabSize {
 			get => indentationTabSize;
 			set => SetProperty(ref indentationTabSize, value);
 		}
 
 		int indentationSize;
-
 		public int IndentationSize {
 			get => indentationSize;
 			set => SetProperty(ref indentationSize, value);
 		}
 
 		bool highlightMatchingBraces;
-
 		public bool HighlightMatchingBraces {
 			get => highlightMatchingBraces;
 			set => SetProperty(ref highlightMatchingBraces, value);
 		}
 
 		bool highlightCurrentLine;
-
 		public bool HighlightCurrentLine {
 			get => highlightCurrentLine;
 			set => SetProperty(ref highlightCurrentLine, value);
 		}
 
 		bool hideEmptyMetadataTables;
-
 		public bool HideEmptyMetadataTables {
 			get => hideEmptyMetadataTables;
 			set => SetProperty(ref hideEmptyMetadataTables, value);
 		}
 
 		bool useNestedNamespaceNodes;
-
 		public bool UseNestedNamespaceNodes {
 			get => useNestedNamespaceNodes;
 			set => SetProperty(ref useNestedNamespaceNodes, value);
 		}
 
 		private bool styleWindowTitleBar;
-
 		public bool StyleWindowTitleBar {
 			get => styleWindowTitleBar;
 			set => SetProperty(ref styleWindowTitleBar, value);
 		}
 
 		private bool showRawOffsetsAndBytesBeforeInstruction;
-
 		public bool ShowRawOffsetsAndBytesBeforeInstruction {
 			get => showRawOffsetsAndBytesBeforeInstruction;
 			set => SetProperty(ref showRawOffsetsAndBytesBeforeInstruction, value);
 		}
 
-		public void CopyValues(DisplaySettings s)
-		{
-			this.Theme = s.Theme;
-			this.SelectedFont = s.selectedFont;
-			this.SelectedFontSize = s.selectedFontSize;
-			this.ShowLineNumbers = s.showLineNumbers;
-			this.ShowMetadataTokens = s.showMetadataTokens;
-			this.ShowMetadataTokensInBase10 = s.showMetadataTokensInBase10;
-			this.ShowDebugInfo = s.showDebugInfo;
-			this.EnableWordWrap = s.enableWordWrap;
-			this.SortResults = s.sortResults;
-			this.FoldBraces = s.foldBraces;
-			this.ExpandMemberDefinitions = s.expandMemberDefinitions;
-			this.ExpandUsingDeclarations = s.expandUsingDeclarations;
-			this.IndentationUseTabs = s.indentationUseTabs;
-			this.IndentationTabSize = s.indentationTabSize;
-			this.IndentationSize = s.indentationSize;
-			this.HighlightMatchingBraces = s.highlightMatchingBraces;
-			this.HighlightCurrentLine = s.highlightCurrentLine;
-			this.HideEmptyMetadataTables = s.hideEmptyMetadataTables;
-			this.UseNestedNamespaceNodes = s.useNestedNamespaceNodes;
-			this.ShowRawOffsetsAndBytesBeforeInstruction = s.showRawOffsetsAndBytesBeforeInstruction;
-			this.StyleWindowTitleBar = s.styleWindowTitleBar;
-		}
+		public XName SectionName => "DisplaySettings";
 
-		public static DisplaySettings Load(ILSpySettings settings, SessionSettings sessionSettings = null)
+		public void LoadFromSection(XElement section)
 		{
-			XElement e = settings["DisplaySettings"];
-			var s = new DisplaySettings {
-				SelectedFont = new FontFamily((string)e.Attribute("Font") ?? "Consolas"),
-				SelectedFontSize = (double?)e.Attribute("FontSize") ?? 10.0 * 4 / 3,
-				ShowLineNumbers = (bool?)e.Attribute("ShowLineNumbers") ?? false,
-				ShowMetadataTokens = (bool?)e.Attribute("ShowMetadataTokens") ?? false,
-				ShowMetadataTokensInBase10 = (bool?)e.Attribute("ShowMetadataTokensInBase10") ?? false,
-				ShowDebugInfo = (bool?)e.Attribute("ShowDebugInfo") ?? false,
-				EnableWordWrap = (bool?)e.Attribute("EnableWordWrap") ?? false,
-				SortResults = (bool?)e.Attribute("SortResults") ?? true,
-				FoldBraces = (bool?)e.Attribute("FoldBraces") ?? false,
-				ExpandMemberDefinitions = (bool?)e.Attribute("ExpandMemberDefinitions") ?? false,
-				ExpandUsingDeclarations = (bool?)e.Attribute("ExpandUsingDeclarations") ?? false,
-				IndentationUseTabs = (bool?)e.Attribute("IndentationUseTabs") ?? true,
-				IndentationSize = (int?)e.Attribute("IndentationSize") ?? 4,
-				IndentationTabSize = (int?)e.Attribute("IndentationTabSize") ?? 4,
-				HighlightMatchingBraces = (bool?)e.Attribute("HighlightMatchingBraces") ?? true,
-				HighlightCurrentLine = (bool?)e.Attribute("HighlightCurrentLine") ?? false,
-				HideEmptyMetadataTables = (bool?)e.Attribute("HideEmptyMetadataTables") ?? true,
-				UseNestedNamespaceNodes = (bool?)e.Attribute("UseNestedNamespaceNodes") ?? false,
-				ShowRawOffsetsAndBytesBeforeInstruction = (bool?)e.Attribute("ShowRawOffsetsAndBytesBeforeInstruction") ?? false,
-				StyleWindowTitleBar = (bool?)e.Attribute("StyleWindowTitleBar") ?? false,
-				Theme = (sessionSettings ?? SettingsService.Instance.SessionSettings).Theme
-			};
-
-			return s;
-		}
-
-		public void Save(XElement root)
+			SelectedFont = new FontFamily((string)section.Attribute("Font") ?? "Consolas");
+			SelectedFontSize = (double?)section.Attribute("FontSize") ?? 10.0 * 4 / 3;
+			ShowLineNumbers = (bool?)section.Attribute("ShowLineNumbers") ?? false;
+			ShowMetadataTokens = (bool?)section.Attribute("ShowMetadataTokens") ?? false;
+			ShowMetadataTokensInBase10 = (bool?)section.Attribute("ShowMetadataTokensInBase10") ?? false;
+			ShowDebugInfo = (bool?)section.Attribute("ShowDebugInfo") ?? false;
+			EnableWordWrap = (bool?)section.Attribute("EnableWordWrap") ?? false;
+			SortResults = (bool?)section.Attribute("SortResults") ?? true;
+			FoldBraces = (bool?)section.Attribute("FoldBraces") ?? false;
+			ExpandMemberDefinitions = (bool?)section.Attribute("ExpandMemberDefinitions") ?? false;
+			ExpandUsingDeclarations = (bool?)section.Attribute("ExpandUsingDeclarations") ?? false;
+			IndentationUseTabs = (bool?)section.Attribute("IndentationUseTabs") ?? true;
+			IndentationSize = (int?)section.Attribute("IndentationSize") ?? 4;
+			IndentationTabSize = (int?)section.Attribute("IndentationTabSize") ?? 4;
+			HighlightMatchingBraces = (bool?)section.Attribute("HighlightMatchingBraces") ?? true;
+			HighlightCurrentLine = (bool?)section.Attribute("HighlightCurrentLine") ?? false;
+			HideEmptyMetadataTables = (bool?)section.Attribute("HideEmptyMetadataTables") ?? true;
+			UseNestedNamespaceNodes = (bool?)section.Attribute("UseNestedNamespaceNodes") ?? false;
+			ShowRawOffsetsAndBytesBeforeInstruction = (bool?)section.Attribute("ShowRawOffsetsAndBytesBeforeInstruction") ?? false;
+			StyleWindowTitleBar = (bool?)section.Attribute("StyleWindowTitleBar") ?? false;
+		}
+
+		public void SaveToSection(XElement section)
 		{
-			var s = this;
-
-			var section = new XElement("DisplaySettings");
-			section.SetAttributeValue("Font", s.SelectedFont.Source);
-			section.SetAttributeValue("FontSize", s.SelectedFontSize);
-			section.SetAttributeValue("ShowLineNumbers", s.ShowLineNumbers);
-			section.SetAttributeValue("ShowMetadataTokens", s.ShowMetadataTokens);
-			section.SetAttributeValue("ShowMetadataTokensInBase10", s.ShowMetadataTokensInBase10);
-			section.SetAttributeValue("ShowDebugInfo", s.ShowDebugInfo);
-			section.SetAttributeValue("EnableWordWrap", s.EnableWordWrap);
-			section.SetAttributeValue("SortResults", s.SortResults);
-			section.SetAttributeValue("FoldBraces", s.FoldBraces);
-			section.SetAttributeValue("ExpandMemberDefinitions", s.ExpandMemberDefinitions);
-			section.SetAttributeValue("ExpandUsingDeclarations", s.ExpandUsingDeclarations);
-			section.SetAttributeValue("IndentationUseTabs", s.IndentationUseTabs);
-			section.SetAttributeValue("IndentationSize", s.IndentationSize);
-			section.SetAttributeValue("IndentationTabSize", s.IndentationTabSize);
-			section.SetAttributeValue("HighlightMatchingBraces", s.HighlightMatchingBraces);
-			section.SetAttributeValue("HighlightCurrentLine", s.HighlightCurrentLine);
-			section.SetAttributeValue("HideEmptyMetadataTables", s.HideEmptyMetadataTables);
-			section.SetAttributeValue("UseNestedNamespaceNodes", s.UseNestedNamespaceNodes);
-			section.SetAttributeValue("ShowRawOffsetsAndBytesBeforeInstruction", s.ShowRawOffsetsAndBytesBeforeInstruction);
-			section.SetAttributeValue("StyleWindowTitleBar", s.StyleWindowTitleBar);
-
-			SettingsService.Instance.SessionSettings.Theme = s.Theme;
-			var sessionSettings = SettingsService.Instance.SessionSettings.ToXml();
-
-			SettingsService.Instance.DisplaySettings.CopyValues(s);
-
-			Update(section);
-			Update(sessionSettings);
-
-			void Update(XElement element)
-			{
-				var existingElement = root.Element(element.Name);
-				if (existingElement != null)
-					existingElement.ReplaceWith(element);
-				else
-					root.Add(element);
-			}
+			section.SetAttributeValue("Font", SelectedFont.Source);
+			section.SetAttributeValue("FontSize", SelectedFontSize);
+			section.SetAttributeValue("ShowLineNumbers", ShowLineNumbers);
+			section.SetAttributeValue("ShowMetadataTokens", ShowMetadataTokens);
+			section.SetAttributeValue("ShowMetadataTokensInBase10", ShowMetadataTokensInBase10);
+			section.SetAttributeValue("ShowDebugInfo", ShowDebugInfo);
+			section.SetAttributeValue("EnableWordWrap", EnableWordWrap);
+			section.SetAttributeValue("SortResults", SortResults);
+			section.SetAttributeValue("FoldBraces", FoldBraces);
+			section.SetAttributeValue("ExpandMemberDefinitions", ExpandMemberDefinitions);
+			section.SetAttributeValue("ExpandUsingDeclarations", ExpandUsingDeclarations);
+			section.SetAttributeValue("IndentationUseTabs", IndentationUseTabs);
+			section.SetAttributeValue("IndentationSize", IndentationSize);
+			section.SetAttributeValue("IndentationTabSize", IndentationTabSize);
+			section.SetAttributeValue("HighlightMatchingBraces", HighlightMatchingBraces);
+			section.SetAttributeValue("HighlightCurrentLine", HighlightCurrentLine);
+			section.SetAttributeValue("HideEmptyMetadataTables", HideEmptyMetadataTables);
+			section.SetAttributeValue("UseNestedNamespaceNodes", UseNestedNamespaceNodes);
+			section.SetAttributeValue("ShowRawOffsetsAndBytesBeforeInstruction", ShowRawOffsetsAndBytesBeforeInstruction);
+			section.SetAttributeValue("StyleWindowTitleBar", StyleWindowTitleBar);
 		}
 	}
 }

ILSpy/Options/DisplaySettingsPanel.xaml

@@ -3,7 +3,6 @@
 			 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 			 xmlns:properties="clr-namespace:ICSharpCode.ILSpy.Properties"
 			 xmlns:local="clr-namespace:ICSharpCode.ILSpy.Options"
-			 xmlns:system="clr-namespace:System;assembly=mscorlib"
 			 xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d"
 			 xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
 			 xmlns:themes="clr-namespace:ICSharpCode.ILSpy.Themes"
@@ -12,7 +11,7 @@
 		<StackPanel Orientation="Vertical">
 			<DockPanel>
 				<Label DockPanel.Dock="Left" Content="{x:Static properties:Resources.DisplaySettingsPanel_Theme}" />
-				<ComboBox ItemsSource="{x:Static themes:ThemeManager.AllThemes}" SelectedItem="{Binding Settings.Theme}" VerticalContentAlignment="Center" Margin="0,0,8,0" />
+				<ComboBox ItemsSource="{x:Static themes:ThemeManager.AllThemes}" SelectedItem="{Binding SessionSettings.Theme}" VerticalContentAlignment="Center" Margin="0,0,8,0" />
 			</DockPanel>
 			<GroupBox Header="{x:Static properties:Resources.Font}">
 				<Grid>

ILSpy/Options/DisplaySettingsViewModel.cs

@@ -8,6 +8,7 @@ using System.Threading.Tasks;
 using System.Windows;
 
 using TomsToolbox.Wpf;
+using ICSharpCode.ILSpy.Themes;
 
 namespace ICSharpCode.ILSpy.Options
 {
@@ -17,6 +18,7 @@ namespace ICSharpCode.ILSpy.Options
 	{
 		private DisplaySettings settings = new();
 		private FontFamily[] fontFamilies;
+		private SessionSettings sessionSettings;
 
 		public DisplaySettingsViewModel()
 		{
@@ -40,6 +42,11 @@ namespace ICSharpCode.ILSpy.Options
 			set => SetProperty(ref settings, value);
 		}
 
+		public SessionSettings SessionSettings {
+			get => sessionSettings;
+			set => SetProperty(ref sessionSettings, value);
+		}
+
 		public FontFamily[] FontFamilies {
 			get => fontFamilies;
 			set => SetProperty(ref fontFamilies, value);
@@ -47,9 +54,10 @@ namespace ICSharpCode.ILSpy.Options
 
 		public int[] FontSizes { get; } = Enumerable.Range(6, 24 - 6 + 1).ToArray();
 
-		public void Load(ILSpySettings spySettings)
+		public void Load(SettingsSnapshot snapshot)
 		{
-			Settings = DisplaySettings.Load(spySettings);
+			Settings = snapshot.GetSettings<DisplaySettings>();
+			SessionSettings = snapshot.GetSettings<SessionSettings>();
 		}
 
 		static bool IsSymbolFont(FontFamily fontFamily)
@@ -77,14 +85,10 @@ namespace ICSharpCode.ILSpy.Options
 				.ToArray();
 		}
 
-		public void Save(XElement root)
-		{
-			Settings.Save(root);
-		}
-
 		public void LoadDefaults()
 		{
-			Settings = new();
+			Settings.LoadFromSection(new XElement("empty"));
+			SessionSettings.Theme = ThemeManager.Current.DefaultTheme;
 		}
 	}
 }

ILSpy/Options/MiscSettings.cs

@@ -19,25 +19,38 @@
 using System;
 using System.Xml.Linq;
 
+using TomsToolbox.Wpf;
+
 namespace ICSharpCode.ILSpyX.Settings
 {
-	public class MiscSettings : IMiscSettings, ISettingsSection<MiscSettings>
+	public class MiscSettings : ObservableObject, ISettingsSection
 	{
-		public MiscSettings()
-		{
+		private bool allowMultipleInstances;
+		private bool loadPreviousAssemblies = true;
+
+		public bool AllowMultipleInstances {
+			get => allowMultipleInstances;
+			set => SetProperty(ref allowMultipleInstances, value);
+		}
+
+		public bool LoadPreviousAssemblies {
+			get => loadPreviousAssemblies;
+			set => SetProperty(ref loadPreviousAssemblies, value);
 		}
 
-		public bool AllowMultipleInstances { get; set; }
-		public bool LoadPreviousAssemblies { get; set; } = true;
+		public XName SectionName => "MiscSettings";
 
-		public static MiscSettings Load(ISettingsProvider settingsProvider)
+		public void LoadFromSection(XElement e)
 		{
-			XElement e = settingsProvider["MiscSettings"];
-			var s = new MiscSettings();
-			s.AllowMultipleInstances = (bool?)e.Attribute(nameof(s.AllowMultipleInstances)) ?? false;
-			s.LoadPreviousAssemblies = (bool?)e.Attribute(nameof(s.LoadPreviousAssemblies)) ?? true;
+			AllowMultipleInstances = (bool?)e.Attribute(nameof(AllowMultipleInstances)) ?? false;
+			LoadPreviousAssemblies = (bool?)e.Attribute(nameof(LoadPreviousAssemblies)) ?? true;
+		}
 
-			return s;
+		public void SaveToSection(XElement section)
+		{
+			section.SetAttributeValue(nameof(AllowMultipleInstances), AllowMultipleInstances);
+			section.SetAttributeValue(nameof(LoadPreviousAssemblies), LoadPreviousAssemblies);
 		}
 	}
 }
+

ILSpy/Options/MiscSettingsPanel.xaml

@@ -2,16 +2,17 @@
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
-             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" mc:Ignorable="d" 
 			 xmlns:properties="clr-namespace:ICSharpCode.ILSpy.Properties"
-			 mc:Ignorable="d" 
+			 xmlns:options="clr-namespace:ICSharpCode.ILSpy.Options"
+			 d:DataContext="{d:DesignInstance options:MiscSettingsViewModel}"
              d:DesignHeight="300" d:DesignWidth="300">
 	<StackPanel Orientation="Vertical">
 		<GroupBox Header="{x:Static properties:Resources.Misc}">
 			<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}" Content="{Binding AddRemoveShellIntegrationText}" Margin="3" />
+				<CheckBox IsChecked="{Binding Settings.AllowMultipleInstances}" Content="{x:Static properties:Resources.AllowMultipleInstances}" />
+				<CheckBox IsChecked="{Binding Settings.LoadPreviousAssemblies}" Content="{x:Static properties:Resources.LoadAssembliesThatWereLoadedInTheLastInstance}"/>
+				<Button Command="{Binding AddRemoveShellIntegrationCommand}" Content="{Binding AddRemoveShellIntegrationText, FallbackValue=temp}" Margin="3" />
 			</StackPanel>
 		</GroupBox>
 	</StackPanel>

ILSpy/Options/MiscSettingsPanel.xaml.cs

@@ -20,45 +20,20 @@ using System.ComponentModel.Composition;
 using System.Windows.Controls;
 using System.Xml.Linq;
 
-using ICSharpCode.ILSpyX.Settings;
+using TomsToolbox.Wpf.Composition.Mef;
 
 namespace ICSharpCode.ILSpy.Options
 {
 	/// <summary>
 	/// Interaction logic for MiscSettingsPanel.xaml
 	/// </summary>
-	[ExportOptionPage(Order = 30)]
+	[DataTemplate(typeof(MiscSettingsViewModel))]
 	[PartCreationPolicy(CreationPolicy.NonShared)]
-	public partial class MiscSettingsPanel : UserControl, IOptionPage
+	public partial class MiscSettingsPanel
 	{
 		public MiscSettingsPanel()
 		{
 			InitializeComponent();
 		}
-
-		public string Title => Properties.Resources.Misc;
-
-		public void Load(ILSpySettings spySettings)
-		{
-			this.DataContext = new MiscSettingsViewModel(SettingsService.Instance.MiscSettings);
-		}
-
-		public void Save(XElement root)
-		{
-			if (DataContext is not IMiscSettings miscSettings)
-				return;
-
-			IMiscSettings.Save(root, miscSettings);
-
-			SettingsService.Instance.MiscSettings = new() {
-				AllowMultipleInstances = miscSettings.AllowMultipleInstances,
-				LoadPreviousAssemblies = miscSettings.LoadPreviousAssemblies
-			};
-		}
-
-		public void LoadDefaults()
-		{
-			this.DataContext = new MiscSettingsViewModel(new());
-		}
 	}
 }

ILSpy/Options/MiscSettingsViewModel.cs

@@ -16,12 +16,12 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
-using System.ComponentModel;
+using System.ComponentModel.Composition;
 using System.IO;
 using System.Reflection;
-using System.Runtime.CompilerServices;
 using System.Windows;
 using System.Windows.Input;
+using System.Xml.Linq;
 
 using ICSharpCode.ILSpy.AppEnv;
 using ICSharpCode.ILSpyX.Settings;
@@ -32,31 +32,14 @@ using TomsToolbox.Wpf;
 
 namespace ICSharpCode.ILSpy.Options
 {
-	public class MiscSettingsViewModel : ObservableObject, IMiscSettings
+	[ExportOptionPage(Order = 30)]
+	[PartCreationPolicy(CreationPolicy.NonShared)]
+	public class MiscSettingsViewModel : ObservableObject, IOptionPage
 	{
-		bool allowMultipleInstances;
-		bool loadPreviousAssemblies = true;
-
-		public MiscSettingsViewModel(MiscSettings s)
-		{
-			AllowMultipleInstances = s.AllowMultipleInstances;
-			LoadPreviousAssemblies = s.LoadPreviousAssemblies;
-		}
-
-		/// <summary>
-		/// Allow multiple instances.
-		/// </summary>
-		public bool AllowMultipleInstances {
-			get => allowMultipleInstances;
-			set => SetProperty(ref allowMultipleInstances, value);
-		}
-
-		/// <summary>
-		/// Load assemblies that were loaded in the previous instance
-		/// </summary>
-		public bool LoadPreviousAssemblies {
-			get => loadPreviousAssemblies;
-			set => SetProperty(ref loadPreviousAssemblies, value);
+		private MiscSettings settings;
+		public MiscSettings Settings {
+			get => settings;
+			set => SetProperty(ref settings, value);
 		}
 
 		public ICommand AddRemoveShellIntegrationCommand => new DelegateCommand(() => AppEnvironment.IsWindows, AddRemoveShellIntegration);
@@ -105,5 +88,17 @@ namespace ICSharpCode.ILSpy.Options
 				return RegistryEntriesExist() ? Properties.Resources.RemoveShellIntegration : Properties.Resources.AddShellIntegration;
 			}
 		}
+
+		public string Title => Properties.Resources.Misc;
+
+		public void Load(SettingsSnapshot settings)
+		{
+			Settings = settings.GetSettings<MiscSettings>();
+		}
+
+		public void LoadDefaults()
+		{
+			Settings.LoadFromSection(new XElement("dummy"));
+		}
 	}
 }

ILSpy/Options/OptionsDialog.xaml.cs

@@ -45,8 +45,9 @@ namespace ICSharpCode.ILSpy.Options
 	public interface IOptionPage
 	{
 		string Title { get; }
-		void Load(ILSpySettings spySettings);
-		void Save(XElement root);
+
+		void Load(SettingsSnapshot settings);
+
 		void LoadDefaults();
 	}
 

ILSpy/Options/OptionsDialogViewModel.cs

@@ -20,6 +20,8 @@ namespace ICSharpCode.ILSpy.Options
 	{
 		private IOptionPage? selectedPage;
 
+		private SettingsSnapshot snapshot;
+
 		private readonly IOptionPage[] optionPages = App.ExportProvider.GetExports<IOptionPage, IOptionsMetadata>("OptionPages")
 			.OrderBy(page => page.Metadata?.Order)
 			.Select(item => item.Value)
@@ -28,11 +30,11 @@ namespace ICSharpCode.ILSpy.Options
 
 		public OptionsDialogViewModel()
 		{
-			var settings = SettingsService.Instance.SpySettings;
+			this.snapshot = SettingsService.Instance.CreateSnapshot();
 
 			foreach (var optionPage in optionPages)
 			{
-				optionPage.Load(settings);
+				optionPage.Load(this.snapshot);
 			}
 
 			OptionPages = optionPages.Select(page => new OptionsItemViewModel(page)).ToArray();
@@ -60,12 +62,7 @@ namespace ICSharpCode.ILSpy.Options
 
 		private void Commit()
 		{
-			SettingsService.Instance.SpySettings.Update(root => {
-				foreach (var optionPage in optionPages)
-				{
-					optionPage.Save(root);
-				}
-			});
+			snapshot.Save();
 		}
 	}
 }

ILSpy/Search/SearchPane.xaml.cs

@@ -20,6 +20,7 @@ using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
+using System.ComponentModel;
 using System.ComponentModel.Composition;
 using System.Diagnostics;
 using System.Text.RegularExpressions;
@@ -66,7 +67,7 @@ namespace ICSharpCode.ILSpy.Search
 
 			ContextMenuProvider.Add(listBox);
 			MessageBus<CurrentAssemblyListChangedEventArgs>.Subscribers += (sender, e) => CurrentAssemblyList_Changed();
-			MessageBus<LanguageSettingsChangedEventArgs>.Subscribers += (sender, e) => LanguageSettings_PropertyChanged();
+			MessageBus<SettingsChangedEventArgs>.Subscribers += (sender, e) => Settings_PropertyChanged(sender, e);
 
 			CompositionTarget.Rendering += UpdateResults;
 		}
@@ -84,8 +85,11 @@ namespace ICSharpCode.ILSpy.Search
 			}
 		}
 
-		void LanguageSettings_PropertyChanged()
+		void Settings_PropertyChanged(object sender, PropertyChangedEventArgs e)
 		{
+			if (sender is not LanguageSettings)
+				return;
+
 			UpdateFilter();
 		}
 

ILSpy/SessionSettings.cs

@@ -17,6 +17,7 @@
 // DEALINGS IN THE SOFTWARE.
 
 using System;
+using System.Collections.Generic;
 using System.ComponentModel;
 using System.Globalization;
 using System.Linq;
@@ -29,7 +30,6 @@ using System.Xml.Linq;
 using ICSharpCode.ILSpy.Docking;
 using ICSharpCode.ILSpy.Themes;
 using ICSharpCode.ILSpyX.Search;
-using ICSharpCode.ILSpyX.Settings;
 
 namespace ICSharpCode.ILSpy
 {
@@ -37,58 +37,37 @@ namespace ICSharpCode.ILSpy
 	/// Per-session setting:
 	/// Loaded at startup; saved at exit.
 	/// </summary>
-	public sealed class SessionSettings : INotifyPropertyChanged
+	public sealed class SessionSettings : ISettingsSection
 	{
-		public SessionSettings(ILSpySettings spySettings)
-		{
-			XElement doc = spySettings["SessionSettings"];
-
-			XElement filterSettings = doc.Element("FilterSettings");
-			if (filterSettings == null)
-				filterSettings = new XElement("FilterSettings");
-
-			this.LanguageSettings = new LanguageSettings(filterSettings);
-
-			this.ActiveAssemblyList = (string)doc.Element("ActiveAssemblyList");
-
-			XElement activeTreeViewPath = doc.Element("ActiveTreeViewPath");
-			if (activeTreeViewPath != null)
-			{
-				this.ActiveTreeViewPath = activeTreeViewPath.Elements().Select(e => Unescape((string)e)).ToArray();
-			}
-			this.ActiveAutoLoadedAssembly = (string)doc.Element("ActiveAutoLoadedAssembly");
-
-			this.WindowState = FromString((string)doc.Element("WindowState"), WindowState.Normal);
-			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);
-			var culture = (string)doc.Element(nameof(CurrentCulture));
-			this.CurrentCulture = string.IsNullOrEmpty(culture) ? null : culture;
+		public XName SectionName => "SessionSettings";
 
-			this.DockLayout = new DockLayoutSettings(doc.Element("DockLayout"));
-		}
-
-		public event PropertyChangedEventHandler PropertyChanged;
-
-		void OnPropertyChanged([CallerMemberName] string propertyName = null)
+		public void LoadFromSection(XElement section)
 		{
-			var args = new PropertyChangedEventArgs(propertyName);
-
-			PropertyChanged?.Invoke(this, args);
-
-			MessageBus.Send(this, new SessionSettingsChangedEventArgs(args));
+			XElement filterSettings = section.Element("FilterSettings") ?? new XElement("FilterSettings");
+
+			LanguageSettings = new(filterSettings);
+			LanguageSettings.PropertyChanged += (sender, e) => PropertyChanged?.Invoke(sender, e);
+
+			ActiveAssemblyList = (string)section.Element("ActiveAssemblyList");
+			ActiveTreeViewPath = section.Element("ActiveTreeViewPath")?.Elements().Select(e => Unescape((string)e)).ToArray();
+			ActiveAutoLoadedAssembly = (string)section.Element("ActiveAutoLoadedAssembly");
+			WindowState = FromString((string)section.Element("WindowState"), WindowState.Normal);
+			WindowBounds = FromString((string)section.Element("WindowBounds"), DefaultWindowBounds);
+			SelectedSearchMode = FromString((string)section.Element("SelectedSearchMode"), SearchMode.TypeAndMember);
+			Theme = FromString((string)section.Element(nameof(Theme)), ThemeManager.Current.DefaultTheme);
+			var culture = (string)section.Element(nameof(CurrentCulture));
+			CurrentCulture = string.IsNullOrEmpty(culture) ? null : culture;
+			DockLayout = new(section.Element("DockLayout"));
 		}
 
-		public LanguageSettings LanguageSettings { get; }
+		public LanguageSettings LanguageSettings { get; set; }
 
 		public SearchMode SelectedSearchMode { get; set; }
 
+		private string theme;
 		public string Theme {
-			get => ThemeManager.Current.Theme;
-			set {
-				ThemeManager.Current.Theme = value;
-				OnPropertyChanged();
-			}
+			get => theme;
+			set => SetProperty(ref theme, value);
 		}
 
 		public string[] ActiveTreeViewPath;
@@ -120,56 +99,49 @@ namespace ICSharpCode.ILSpy
 
 		public WindowState WindowState;
 		public Rect WindowBounds;
-		internal static Rect DefaultWindowBounds = new Rect(10, 10, 750, 550);
+		internal static Rect DefaultWindowBounds = new(10, 10, 750, 550);
 
-		public DockLayoutSettings DockLayout { get; }
+		public DockLayoutSettings DockLayout { get; set; }
 
-		public XElement ToXml()
+		public void SaveToSection(XElement section)
 		{
-			XElement doc = new XElement("SessionSettings");
-			doc.Add(this.LanguageSettings.SaveAsXml());
+			section.RemoveAll();
+
+			section.Add(this.LanguageSettings.SaveAsXml());
 			if (this.ActiveAssemblyList != null)
 			{
-				doc.Add(new XElement("ActiveAssemblyList", this.ActiveAssemblyList));
+				section.Add(new XElement("ActiveAssemblyList", this.ActiveAssemblyList));
 			}
 			if (this.ActiveTreeViewPath != null)
 			{
-				doc.Add(new XElement("ActiveTreeViewPath", ActiveTreeViewPath.Select(p => new XElement("Node", Escape(p)))));
+				section.Add(new XElement("ActiveTreeViewPath", ActiveTreeViewPath.Select(p => new XElement("Node", Escape(p)))));
 			}
 			if (this.ActiveAutoLoadedAssembly != null)
 			{
-				doc.Add(new XElement("ActiveAutoLoadedAssembly", this.ActiveAutoLoadedAssembly));
+				section.Add(new XElement("ActiveAutoLoadedAssembly", this.ActiveAutoLoadedAssembly));
 			}
-			doc.Add(new XElement("WindowState", ToString(this.WindowState)));
-			doc.Add(new XElement("WindowBounds", ToString(this.WindowBounds)));
-			doc.Add(new XElement("SelectedSearchMode", ToString(this.SelectedSearchMode)));
-			doc.Add(new XElement(nameof(Theme), ToString(this.Theme)));
+			section.Add(new XElement("WindowState", ToString(this.WindowState)));
+			section.Add(new XElement("WindowBounds", ToString(this.WindowBounds)));
+			section.Add(new XElement("SelectedSearchMode", ToString(this.SelectedSearchMode)));
+			section.Add(new XElement(nameof(Theme), ToString(this.Theme)));
 			if (this.CurrentCulture != null)
 			{
-				doc.Add(new XElement(nameof(CurrentCulture), this.CurrentCulture));
+				section.Add(new XElement(nameof(CurrentCulture), this.CurrentCulture));
 			}
-
 			var dockLayoutElement = new XElement("DockLayout");
 			if (DockLayout.Valid)
 			{
 				dockLayoutElement.Add(DockLayout.SaveAsXml());
 			}
-			doc.Add(dockLayoutElement);
-			return doc;
+			section.Add(dockLayoutElement);
 		}
 
-		public void Save()
-		{
-			var doc = ToXml();
-			SettingsService.Instance.SpySettings.SaveSettings(doc);
-		}
-
-		static Regex regex = new Regex("\\\\x(?<num>[0-9A-f]{4})");
+		static Regex regex = new("\\\\x(?<num>[0-9A-f]{4})");
 		private string activeAssemblyList;
 
 		static string Escape(string p)
 		{
-			StringBuilder sb = new StringBuilder();
+			StringBuilder sb = new();
 			foreach (char ch in p)
 			{
 				if (char.IsLetterOrDigit(ch))
@@ -205,5 +177,21 @@ namespace ICSharpCode.ILSpy
 			TypeConverter c = TypeDescriptor.GetConverter(typeof(T));
 			return c.ConvertToInvariantString(obj);
 		}
+
+		public event PropertyChangedEventHandler PropertyChanged;
+
+		private void OnPropertyChanged([CallerMemberName] string propertyName = null)
+		{
+			PropertyChanged?.Invoke(this, new(propertyName));
+		}
+
+		private bool SetProperty<T>(ref T field, T value, [CallerMemberName] string propertyName = null)
+		{
+			if (EqualityComparer<T>.Default.Equals(field, value))
+				return false;
+			field = value;
+			OnPropertyChanged(propertyName);
+			return true;
+		}
 	}
 }

ILSpy/Themes/ThemeManager.cs

@@ -20,6 +20,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Linq;
 using System.Windows;
 using System.Windows.Controls;
@@ -42,6 +43,7 @@ namespace ICSharpCode.ILSpy.Themes
 		private ThemeManager()
 		{
 			Application.Current.Resources.MergedDictionaries.Add(_themeDictionaryContainer);
+			MessageBus<SettingsChangedEventArgs>.Subscribers += (sender, e) => Settings_Changed(sender, e);
 		}
 
 		public string DefaultTheme => "Light";
@@ -199,5 +201,13 @@ namespace ICSharpCode.ILSpy.Themes
 			var b = (byte)((b1 + m) * 255f);
 			return (r, g, b);
 		}
+
+		private void Settings_Changed(object? sender, PropertyChangedEventArgs e)
+		{
+			if (sender is not SessionSettings settings || e.PropertyName != nameof(SessionSettings.Theme))
+				return;
+
+			Theme = settings.Theme;
+		}
 	}
 }

ILSpy/TreeNodes/ILSpyTreeNode.cs

@@ -40,9 +40,9 @@ namespace ICSharpCode.ILSpy.TreeNodes
 	{
 		bool childrenNeedFiltering;
 
-		public ILSpyTreeNode()
+		protected ILSpyTreeNode()
 		{
-			MessageBus<LanguageSettingsChangedEventArgs>.Subscribers += LanguageSettings_Changed;
+			MessageBus<SettingsChangedEventArgs>.Subscribers += (sender, e) => Settings_Changed(sender, e);
 		}
 
 		LanguageSettings LanguageSettings => SettingsService.Instance.SessionSettings.LanguageSettings;
@@ -127,8 +127,13 @@ namespace ICSharpCode.ILSpy.TreeNodes
 			}
 		}
 
-		protected virtual void LanguageSettings_Changed(object sender, EventArgs e)
+		protected virtual void Settings_Changed(object sender, PropertyChangedEventArgs e)
 		{
+			if (sender is not ILSpy.LanguageSettings)
+				return;
+			if (e.PropertyName is not (nameof(LanguageSettings.Language) or nameof(LanguageSettings.LanguageVersion)))
+				return;
+
 			RaisePropertyChanged(nameof(Text));
 			if (IsVisible)
 			{

ILSpy/Updates/NotifyOfUpdatesStrategy.cs

@@ -61,7 +61,7 @@ namespace ICSharpCode.ILSpy.Updates
 		/// Returns the download URL if an update is available.
 		/// Returns null if no update is available, or if no check was performed.
 		/// </summary>
-		public static async Task<string> CheckForUpdatesIfEnabledAsync(ILSpySettings spySettings)
+		public static async Task<string> CheckForUpdatesIfEnabledAsync(ISettingsProvider spySettings)
 		{
 			UpdateSettings s = new UpdateSettings(spySettings);
 
@@ -87,7 +87,7 @@ namespace ICSharpCode.ILSpy.Updates
 			}
 		}
 
-		public static Task<string> CheckForUpdatesAsync(ILSpySettings spySettings)
+		public static Task<string> CheckForUpdatesAsync(ISettingsProvider spySettings)
 		{
 			UpdateSettings s = new UpdateSettings(spySettings);
 			return CheckForUpdateInternal(s);

ILSpy/Updates/UpdateSettings.cs

@@ -26,7 +26,7 @@ namespace ICSharpCode.ILSpy.Updates
 {
 	sealed class UpdateSettings : INotifyPropertyChanged
 	{
-		public UpdateSettings(ILSpySettings spySettings)
+		public UpdateSettings(ISettingsProvider spySettings)
 		{
 			XElement s = spySettings["UpdateSettings"];
 			this.automaticUpdateCheckEnabled = (bool?)s.Element("AutomaticUpdateCheckEnabled") ?? true;

ILSpy/Util/MessageBus.cs

@@ -52,9 +52,7 @@ namespace ICSharpCode.ILSpy.Util
 
 	public class CurrentAssemblyListChangedEventArgs(NotifyCollectionChangedEventArgs e) : WrappedEventArgs<NotifyCollectionChangedEventArgs>(e);
 
-	public class LanguageSettingsChangedEventArgs(PropertyChangedEventArgs e) : WrappedEventArgs<PropertyChangedEventArgs>(e);
-
-	public class SessionSettingsChangedEventArgs(PropertyChangedEventArgs e) : WrappedEventArgs<PropertyChangedEventArgs>(e);
+	public class SettingsChangedEventArgs(PropertyChangedEventArgs e) : WrappedEventArgs<PropertyChangedEventArgs>(e);
 
 	public class NavigateToReferenceEventArgs(object reference, bool inNewTabPage = false) : EventArgs
 	{

ILSpy/Util/SettingsService.cs

@@ -1,4 +1,7 @@
 using System;
+using System.Collections.Concurrent;
+using System.ComponentModel;
+using System.Xml.Linq;
 
 using ICSharpCode.Decompiler;
 using ICSharpCode.ILSpy.Options;
@@ -6,36 +9,102 @@ using ICSharpCode.ILSpy.ViewModels;
 using ICSharpCode.ILSpyX;
 using ICSharpCode.ILSpyX.Settings;
 
+using DecompilerSettings = ICSharpCode.ILSpy.Options.DecompilerSettings;
+
+#nullable enable
+
 namespace ICSharpCode.ILSpy.Util
 {
-	public class SettingsService
+	public interface ISettingsSection : INotifyPropertyChanged
 	{
-		public static readonly SettingsService Instance = new();
+		XName SectionName { get; }
+
+		void LoadFromSection(XElement section);
+
+		void SaveToSection(XElement section);
+	}
+
+	public abstract class SettingsServiceBase
+	{
+		protected readonly ConcurrentDictionary<Type, ISettingsSection> sections = new();
+
+		public ISettingsProvider SpySettings;
+
+		protected SettingsServiceBase(ISettingsProvider spySettings)
+		{
+			SpySettings = spySettings;
+		}
+
+		public T GetSettings<T>() where T : ISettingsSection, new()
+		{
+			return (T)sections.GetOrAdd(typeof(T), _ => {
+				T section = new T();
+
+				var sectionElement = SpySettings[section.SectionName];
+
+				section.LoadFromSection(sectionElement);
+				section.PropertyChanged += Section_PropertyChanged;
 
-		private SettingsService()
+				return section;
+			});
+		}
+
+		protected virtual void Section_PropertyChanged(object? sender, PropertyChangedEventArgs e)
+		{
+		}
+	}
+
+	public class SettingsSnapshot : SettingsServiceBase
+	{
+		private readonly SettingsService parent;
+
+		public SettingsSnapshot(SettingsService parent) : base(parent.SpySettings)
 		{
-			SpySettings = ILSpySettings.Load();
-			SessionSettings = new(SpySettings);
-			DecompilerSettings = ISettingsProvider.LoadDecompilerSettings(SpySettings);
-			DisplaySettings = DisplaySettings.Load(SpySettings, SessionSettings);
-			MiscSettings = MiscSettings.Load(SpySettings);
-			AssemblyListManager = new(SpySettings) {
-				ApplyWinRTProjections = DecompilerSettings.ApplyWindowsRuntimeProjections,
-				UseDebugSymbols = DecompilerSettings.UseDebugSymbols
-			};
+			this.parent = parent;
 		}
 
-		public ILSpySettings SpySettings { get; }
+		public void Save()
+		{
+			SpySettings.Update(root => {
+				foreach (var section in sections.Values)
+				{
+					var element = SpySettings[section.SectionName];
+
+					section.SaveToSection(element);
 
-		public SessionSettings SessionSettings { get; }
+					var existingElement = root.Element(section.SectionName);
+					if (existingElement != null)
+						existingElement.ReplaceWith(element);
+					else
+						root.Add(element);
+				}
+			});
 
-		public DecompilerSettings DecompilerSettings { get; set; }
+			parent.Reload();
+		}
+	}
 
-		public DisplaySettings DisplaySettings { get; }
+	public class SettingsService : SettingsServiceBase
+	{
+		public static readonly SettingsService Instance = new();
 
-		public MiscSettings MiscSettings { get; set; }
+		private SettingsService() : base(LoadSettings())
+		{
+		}
 
-		public AssemblyListManager AssemblyListManager { get; }
+		public SessionSettings SessionSettings => GetSettings<SessionSettings>();
+
+		public DecompilerSettings DecompilerSettings => GetSettings<DecompilerSettings>();
+
+		public DisplaySettings DisplaySettings => GetSettings<DisplaySettings>();
+
+		public MiscSettings MiscSettings => GetSettings<MiscSettings>();
+
+		private AssemblyListManager? assemblyListManager;
+		public AssemblyListManager AssemblyListManager => assemblyListManager ??= new(SpySettings) {
+			ApplyWinRTProjections = DecompilerSettings.ApplyWindowsRuntimeProjections,
+			UseDebugSymbols = DecompilerSettings.UseDebugSymbols
+		};
 
 		public DecompilationOptions CreateDecompilationOptions(TabPageModel tabPage)
 		{
@@ -56,5 +125,57 @@ namespace ICSharpCode.ILSpy.Util
 				return AssemblyListManager.CreateList(AssemblyListManager.DefaultListName);
 			}
 		}
+
+		private bool reloading;
+
+		public void Reload()
+		{
+			reloading = true;
+
+			try
+			{
+				SpySettings = ILSpySettings.Load();
+
+				foreach (var section in sections.Values)
+				{
+					var element = SpySettings[section.SectionName];
+
+					section.LoadFromSection(element);
+				}
+			}
+			finally
+			{
+				reloading = false;
+			}
+		}
+
+		public SettingsSnapshot CreateSnapshot()
+		{
+			return new(this);
+		}
+
+		protected override void Section_PropertyChanged(object? sender, PropertyChangedEventArgs e)
+		{
+			base.Section_PropertyChanged(sender, e);
+
+			if (!reloading)
+			{
+				throw new InvalidOperationException("Settings are read only, use a snapshot to modify.");
+			}
+
+			if (sender is DecompilerSettings decompilerSettings && assemblyListManager != null)
+			{
+				assemblyListManager.ApplyWinRTProjections = decompilerSettings.ApplyWindowsRuntimeProjections;
+				assemblyListManager.UseDebugSymbols = decompilerSettings.UseDebugSymbols;
+			}
+
+			MessageBus.Send(sender, new SettingsChangedEventArgs(e));
+		}
+
+		private static ILSpySettings LoadSettings()
+		{
+			ILSpySettings.SettingsFilePathProvider = new ILSpySettingsFilePathProvider();
+			return ILSpySettings.Load();
+		}
 	}
 }

ILSpy/Views/DebugSteps.xaml.cs

@@ -33,7 +33,7 @@ namespace ICSharpCode.ILSpy
 			InitializeComponent();
 
 #if DEBUG
-			MessageBus<LanguageSettingsChangedEventArgs>.Subscribers += (sender, e) => LanguageSettings_PropertyChanged(sender, e);
+			MessageBus<SettingsChangedEventArgs>.Subscribers += (sender, e) => Settings_PropertyChanged(sender, e);
 			MessageBus<AssemblyTreeSelectionChangedEventArgs>.Subscribers += SelectionChanged;
 
 			writingOptions.PropertyChanged += WritingOptions_PropertyChanged;
@@ -60,10 +60,13 @@ namespace ICSharpCode.ILSpy
 			});
 		}
 
-		private void LanguageSettings_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
+		private void Settings_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
 		{
 #if DEBUG
-			if (e.PropertyName == "Language")
+			if (sender is not LanguageSettings)
+				return;
+
+			if (e.PropertyName == nameof(LanguageSettings.Language))
 			{
 				if (language != null)
 				{

TestPlugin/CustomOptionPage.xaml

@@ -1,8 +1,13 @@
 <UserControl x:Class="TestPlugin.CustomOptionPage"
 	xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
-	xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+	xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+	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:testPlugin="clr-namespace:TestPlugin"
+	d:DataContext="{d:DesignInstance testPlugin:CustomOptionsViewModel}"
+	>
 	<StackPanel>
-		<CheckBox IsChecked="{Binding UselessOption1}">Useless option 1</CheckBox>
-		<Slider Minimum="0" Maximum="100" Value="{Binding UselessOption2}"/>
+		<CheckBox IsChecked="{Binding  Options.UselessOption1}">Useless option 1</CheckBox>
+		<Slider Minimum="0" Maximum="100" Value="{Binding Options.UselessOption2}"/>
 	</StackPanel>
 </UserControl>

TestPlugin/CustomOptionPage.xaml.cs

@@ -1,100 +1,80 @@
 // Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
 // This code is distributed under MIT X11 license (for details please see \doc\license.txt)
 
-using System.ComponentModel;
 using System.ComponentModel.Composition;
-using System.Windows.Controls;
 using System.Xml.Linq;
 
 using ICSharpCode.ILSpy.Options;
-using ICSharpCode.ILSpyX.Settings;
+using ICSharpCode.ILSpy.Util;
+
+using TomsToolbox.Wpf;
+using TomsToolbox.Wpf.Composition.Mef;
 
 namespace TestPlugin
 {
-	[ExportOptionPage(Order = 0)]
+	[DataTemplate(typeof(CustomOptionsViewModel))]
 	[PartCreationPolicy(CreationPolicy.NonShared)]
-	partial class CustomOptionPage : UserControl, IOptionPage
+	partial class CustomOptionPage
 	{
-		static readonly XNamespace ns = "http://www.ilspy.net/testplugin";
-
 		public CustomOptionPage()
 		{
 			InitializeComponent();
 		}
+	}
+
+	[ExportOptionPage(Order = 0)]
+	class CustomOptionsViewModel : ObservableObject, IOptionPage
+	{
+		private Options options;
 
 		public string Title => "TestPlugin";
 
-		public void Load(ILSpySettings spySettings)
-		{
-			// For loading options, use ILSpySetting's indexer.
-			// If the specified section does exist, the indexer will return a new empty element.
-			XElement e = spySettings[ns + "CustomOptions"];
-			// Now load the options from the XML document:
-			Options s = new Options();
-			s.UselessOption1 = (bool?)e.Attribute("useless1") ?? s.UselessOption1;
-			s.UselessOption2 = (double?)e.Attribute("useless2") ?? s.UselessOption2;
-			this.DataContext = s;
+		public Options Options {
+			get => options;
+			set => SetProperty(ref options, value);
 		}
 
-		public void LoadDefaults()
+		public void Load(SettingsSnapshot snapshot)
 		{
-			this.DataContext = new Options();
+			this.Options = snapshot.GetSettings<Options>();
 		}
 
-		public void Save(XElement root)
+		public void LoadDefaults()
 		{
-			Options s = (Options)this.DataContext;
-			// Save the options back into XML:
-			XElement section = new XElement(ns + "CustomOptions");
-			section.SetAttributeValue("useless1", s.UselessOption1);
-			section.SetAttributeValue("useless2", s.UselessOption2);
-
-			// Replace the existing section in the settings file, or add a new section,
-			// if required.
-			XElement existingElement = root.Element(ns + "CustomOptions");
-			if (existingElement != null)
-				existingElement.ReplaceWith(section);
-			else
-				root.Add(section);
+			Options.LoadFromSection(new XElement("dummy"));
 		}
 	}
 
-	class Options : INotifyPropertyChanged
+	class Options : ObservableObject, ISettingsSection
 	{
+		static readonly XNamespace ns = "http://www.ilspy.net/testplugin";
+
 		bool uselessOption1;
 
 		public bool UselessOption1 {
-			get { return uselessOption1; }
-			set {
-				if (uselessOption1 != value)
-				{
-					uselessOption1 = value;
-					OnPropertyChanged("UselessOption1");
-				}
-			}
+			get => uselessOption1;
+			set => SetProperty(ref uselessOption1, value);
 		}
 
 		double uselessOption2;
 
 		public double UselessOption2 {
-			get { return uselessOption2; }
-			set {
-				if (uselessOption2 != value)
-				{
-					uselessOption2 = value;
-					OnPropertyChanged("UselessOption2");
-				}
-			}
+			get => uselessOption2;
+			set => SetProperty(ref uselessOption2, value);
 		}
 
-		public event PropertyChangedEventHandler PropertyChanged;
+		public XName SectionName { get; } = ns + "CustomOptions";
+
+		public void LoadFromSection(XElement e)
+		{
+			UselessOption1 = (bool?)e.Attribute("useless1") ?? false;
+			UselessOption2 = (double?)e.Attribute("useless2") ?? 50.0;
+		}
 
-		protected virtual void OnPropertyChanged(string propertyName)
+		public void SaveToSection(XElement section)
 		{
-			if (PropertyChanged != null)
-			{
-				PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
-			}
+			section.SetAttributeValue("useless1", UselessOption1);
+			section.SetAttributeValue("useless2", UselessOption2);
 		}
 	}
 }