Options UI as a Dock document tab (port of WPF Options dialog)

Replaces the WPF modal Options dialog with a Dock document tab — opens via
View → Options at the same MenuOrder=999 mount point, hosts the same three
panels (Decompiler / Display / Misc), and uses the same SettingsSnapshot
commit pattern so closing the tab without Apply discards in-flight edits.
Re-invoking View → Options while one's open just focuses the existing tab.

Assisted-by: Claude:claude-opus-4-7:Claude Code

ILSpy.Tests/Options/OptionsTabTests.cs

@@ -0,0 +1,210 @@
+// Copyright (c) 2026 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.Linq;
+using System.Threading.Tasks;
+
+using Avalonia.Headless.NUnit;
+
+using AwesomeAssertions;
+
+using ICSharpCode.ILSpy.Properties;
+
+using ILSpy;
+using ILSpy.AppEnv;
+using ILSpy.Commands;
+using ILSpy.Docking;
+using ILSpy.Options;
+using ILSpy.ViewModels;
+using ILSpy.Views;
+
+using NUnit.Framework;
+
+namespace ICSharpCode.ILSpy.Tests;
+
+[TestFixture]
+public class OptionsTabTests
+{
+	[AvaloniaTest]
+	public void Options_Command_Is_Exported_To_View_Menu_With_Last_MenuOrder()
+	{
+		// Mirrors the WPF mounting point. MenuOrder 999 puts it last under View;
+		// MenuCategory "Options" gives it its own separator group.
+		var registry = AppComposition.Current.GetExport<MainMenuCommandRegistry>();
+		var entry = registry.Commands
+			.SingleOrDefault(c => c.Metadata.Header == nameof(Resources._Options));
+		((object?)entry).Should().NotBeNull(
+			"View → Options must be exported via [ExportMainMenuCommand]");
+		entry!.Metadata.ParentMenuID.Should().Be(nameof(Resources._View));
+		entry.Metadata.MenuOrder.Should().Be(999);
+		entry.Metadata.MenuCategory.Should().Be(nameof(Resources.Options));
+	}
+
+	[AvaloniaTest]
+	public void Invoking_ShowOptionsCommand_Opens_Document_Tab_With_OptionsPageModel()
+	{
+		// The Options window-equivalent shows up as a regular Dock document tab with
+		// OptionsPageModel as its Content. IsStaticContent flags it so tree-node selections
+		// route to a fresh decompile tab instead of overwriting it.
+		var window = AppComposition.Current.GetExport<MainWindow>();
+		window.Show();
+		var vm = (MainWindowViewModel)window.DataContext!;
+		var registry = AppComposition.Current.GetExport<MainMenuCommandRegistry>();
+		var command = registry.Commands
+			.Single(c => c.Metadata.Header == nameof(Resources._Options))
+			.CreateExport().Value;
+
+		command.Execute(null);
+
+		var docs = vm.DockWorkspace.Documents?.VisibleDockables;
+		((object?)docs).Should().NotBeNull();
+		var optionsTab = docs!.OfType<ContentTabPage>()
+			.SingleOrDefault(t => t.Content is OptionsPageModel);
+		((object?)optionsTab).Should().NotBeNull(
+			"a ContentTabPage hosting an OptionsPageModel must land in the documents dock");
+		var model = (OptionsPageModel)optionsTab!.Content!;
+		model.IsStaticContent.Should().BeTrue(
+			"the Options tab must be flagged static so tree-node selections leave it alone");
+	}
+
+	[AvaloniaTest]
+	public void OptionsPageModel_Surfaces_The_Three_Panels_In_MEF_Order()
+	{
+		// Decompiler / Display / Misc, ordered by ExportOptionPage(Order=10/20/30).
+		// Titles come from the embedded WPF Resources.resx so they match the WPF host
+		// byte-for-byte.
+		var window = AppComposition.Current.GetExport<MainWindow>();
+		window.Show();
+		var registry = AppComposition.Current.GetExport<MainMenuCommandRegistry>();
+		var command = registry.Commands
+			.Single(c => c.Metadata.Header == nameof(Resources._Options))
+			.CreateExport().Value;
+		command.Execute(null);
+
+		var vm = (MainWindowViewModel)window.DataContext!;
+		var model = (OptionsPageModel)vm.DockWorkspace.Documents!.VisibleDockables!
+			.OfType<ContentTabPage>().First(t => t.Content is OptionsPageModel).Content!;
+
+		model.Pages.Should().HaveCount(3);
+		model.Pages[0].Title.Should().Be(Resources.Decompiler);
+		model.Pages[1].Title.Should().Be(Resources.Display);
+		model.Pages[2].Title.Should().Be(Resources.Misc);
+	}
+
+	[AvaloniaTest]
+	public void Reinvoking_ShowOptionsCommand_Focuses_Existing_Tab_Without_Spawning_A_Second()
+	{
+		// Single-instance behaviour — re-firing the command while Options is already open
+		// just reactivates the existing tab. Mirrors WPF's modal-stack uniqueness.
+		var window = AppComposition.Current.GetExport<MainWindow>();
+		window.Show();
+		var vm = (MainWindowViewModel)window.DataContext!;
+		var registry = AppComposition.Current.GetExport<MainMenuCommandRegistry>();
+		var command = registry.Commands
+			.Single(c => c.Metadata.Header == nameof(Resources._Options))
+			.CreateExport().Value;
+
+		command.Execute(null);
+		command.Execute(null);
+
+		var optionsTabs = vm.DockWorkspace.Documents!.VisibleDockables!
+			.OfType<ContentTabPage>().Where(t => t.Content is OptionsPageModel).ToList();
+		optionsTabs.Should().HaveCount(1, "re-firing the command must focus, not duplicate");
+	}
+
+	[AvaloniaTest]
+	public async Task Apply_Writes_Snapshot_Through_To_Live_DecompilerSettings()
+	{
+		// Snapshot pattern: changes in the panel's settings instance don't reach the live
+		// service until Apply. After Apply, SettingsService.DecompilerSettings reflects the
+		// new value. Toggling a property on the snapshot copy alone shouldn't affect the
+		// live instance until Apply is called.
+		var window = AppComposition.Current.GetExport<MainWindow>();
+		window.Show();
+		var settings = AppComposition.Current.GetExport<SettingsService>();
+		var registry = AppComposition.Current.GetExport<MainMenuCommandRegistry>();
+
+		var liveBefore = settings.DecompilerSettings.UsingDeclarations;
+
+		registry.Commands.Single(c => c.Metadata.Header == nameof(Resources._Options))
+			.CreateExport().Value.Execute(null);
+
+		var vm = (MainWindowViewModel)window.DataContext!;
+		var model = (OptionsPageModel)vm.DockWorkspace.Documents!.VisibleDockables!
+			.OfType<ContentTabPage>().First(t => t.Content is OptionsPageModel).Content!;
+		var decompilerPage = (DecompilerSettingsViewModel)model.Pages[0];
+
+		// Find the UsingDeclarations item in the reflection-built tree and flip it.
+		var usingDecl = decompilerPage.Settings
+			.SelectMany(g => g.Settings)
+			.First(s => s.Property.Name == nameof(global::ICSharpCode.Decompiler.DecompilerSettings.UsingDeclarations));
+		usingDecl.IsEnabled = !liveBefore;
+
+		// Live service unaffected so far — only the snapshot copy changed.
+		// Snapshot edits must not leak into the live service before Apply.
+		settings.DecompilerSettings.UsingDeclarations.Should().Be(liveBefore);
+
+		// Apply — flushes snapshot to XML and reloads sections so live values match.
+		model.ApplyCommand.Execute(null);
+		await Task.Yield();
+
+		// After Apply, the live service must see the panel's toggled value.
+		settings.DecompilerSettings.UsingDeclarations.Should().Be(!liveBefore);
+
+		// Clean-up: restore the original so the persisted XML doesn't pollute later tests.
+		usingDecl.IsEnabled = liveBefore;
+		model.ApplyCommand.Execute(null);
+	}
+
+	[AvaloniaTest]
+	public void Reset_Current_Page_Restores_Defaults_For_The_Active_Panel_Only()
+	{
+		// Reset operates on the selected panel only. After flipping a few values and clicking
+		// Reset, every DecompilerSettings property is back to its `new DecompilerSettings()`
+		// default; Display and Misc panels are untouched (verified by leaving them alone).
+		var window = AppComposition.Current.GetExport<MainWindow>();
+		window.Show();
+		var registry = AppComposition.Current.GetExport<MainMenuCommandRegistry>();
+		registry.Commands.Single(c => c.Metadata.Header == nameof(Resources._Options))
+			.CreateExport().Value.Execute(null);
+
+		var vm = (MainWindowViewModel)window.DataContext!;
+		var model = (OptionsPageModel)vm.DockWorkspace.Documents!.VisibleDockables!
+			.OfType<ContentTabPage>().First(t => t.Content is OptionsPageModel).Content!;
+		var decompilerPage = (DecompilerSettingsViewModel)model.Pages[0];
+		model.SelectedPage = decompilerPage;
+
+		// Flip a known-default-true setting to false.
+		var item = decompilerPage.Settings
+			.SelectMany(g => g.Settings)
+			.First(s => s.Property.Name == nameof(global::ICSharpCode.Decompiler.DecompilerSettings.UsingDeclarations));
+		var defaultValue = (bool)item.Property.GetValue(new global::ICSharpCode.Decompiler.DecompilerSettings())!;
+		item.IsEnabled = !defaultValue;
+		// Sanity: precondition flip took effect.
+		item.IsEnabled.Should().Be(!defaultValue);
+
+		model.ResetCurrentPageCommand.Execute(null);
+
+		// After reset, the reflection-rebuilt item list has the snapshot's defaults.
+		var refreshedItem = decompilerPage.Settings
+			.SelectMany(g => g.Settings)
+			.First(s => s.Property.Name == nameof(global::ICSharpCode.Decompiler.DecompilerSettings.UsingDeclarations));
+		// Reset must restore the panel's settings to `new DecompilerSettings()` defaults.
+		refreshedItem.IsEnabled.Should().Be(defaultValue);
+	}
+}

ILSpy/Commands/ShowOptionsCommand.cs

@@ -0,0 +1,69 @@
+// Copyright (c) 2026 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.Collections.Generic;
+using System.Composition;
+using System.Linq;
+
+using ICSharpCode.ILSpy.Properties;
+
+using ILSpy.Docking;
+using ILSpy.Options;
+using ILSpy.ViewModels;
+
+namespace ILSpy.Commands
+{
+	/// <summary>
+	/// Opens (or focuses, if already open) the Options document tab. Mounted under the View
+	/// menu mirroring the WPF host's `ShowOptionsCommand`. Ensures a single open instance —
+	/// re-invocation just reactivates the existing tab.
+	/// </summary>
+	[ExportMainMenuCommand(ParentMenuID = nameof(Resources._View), Header = nameof(Resources._Options), MenuCategory = nameof(Resources.Options), MenuOrder = 999)]
+	[Shared]
+	[method: ImportingConstructor]
+	internal sealed class ShowOptionsCommand(
+		DockWorkspace dockWorkspace,
+		SettingsService settingsService,
+		// "OptionPages" is the named MEF contract every ExportOptionPageAttribute publishes
+		// under (see ExportOptionPageAttribute ctor). [ImportMany] alone resolves to the
+		// default contract for IOptionPage and would come up empty.
+		[ImportMany("OptionPages")] IEnumerable<ExportFactory<IOptionPage, IOptionsMetadata>> optionPages) : SimpleCommand
+	{
+		public override void Execute(object? parameter)
+		{
+			var existing = FindExistingOptionsTab();
+			if (existing != null && dockWorkspace.Documents != null)
+			{
+				dockWorkspace.Factory.SetActiveDockable(existing);
+				dockWorkspace.Factory.SetFocusedDockable(dockWorkspace.Documents, existing);
+				return;
+			}
+
+			var model = new OptionsPageModel(settingsService, optionPages);
+			dockWorkspace.OpenNewTab(model);
+		}
+
+		ContentTabPage? FindExistingOptionsTab()
+		{
+			var docs = dockWorkspace.Documents?.VisibleDockables;
+			if (docs == null)
+				return null;
+			return docs.OfType<ContentTabPage>().FirstOrDefault(t => t.Content is OptionsPageModel);
+		}
+	}
+}

ILSpy/Commands/ViewCommands.cs

@@ -40,10 +40,5 @@ namespace ILSpy.Commands
 		public override void Execute(object? parameter) => assemblyTreeModel.CollapseAll();
 	}
 
-	[ExportMainMenuCommand(ParentMenuID = nameof(Resources._View), Header = nameof(Resources._Options), MenuCategory = nameof(Resources.Options), MenuOrder = 999)]
-	[Shared]
-	sealed class ShowOptionsCommand : SimpleCommand
-	{
-		public override void Execute(object? parameter) => NotImplementedDialog.Show(Resources._Options);
-	}
+	// ShowOptionsCommand moved to its own file (Commands/ShowOptionsCommand.cs) — see there.
 }

ILSpy/Docking/DockWorkspace.cs

@@ -62,6 +62,11 @@ namespace ILSpy.Docking
 
 		public IFactory Factory => factory;
 
+		/// <summary>The documents dock — direct access to the carve-out tabs collection.
+		/// Used by commands that need to scan existing tabs for ensure-single-instance
+		/// behaviour (e.g. ShowOptionsCommand).</summary>
+		public IDocumentDock? Documents => factory.Documents;
+
 		public IRelayCommand NavigateBackCommand { get; }
 		public IRelayCommand NavigateForwardCommand { get; }
 		public IRelayCommand<NavigationEntry> NavigateToHistoryCommand { get; }

ILSpy/Options/DecompilerSettingsPanel.axaml

@@ -0,0 +1,28 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:vm="using:ILSpy.Options"
+             mc:Ignorable="d" d:DesignWidth="700" d:DesignHeight="500"
+             x:Class="ILSpy.Options.Panels.DecompilerSettingsPanel"
+             x:DataType="vm:DecompilerSettingsViewModel">
+	<ScrollViewer Padding="6">
+		<ItemsControl ItemsSource="{Binding Settings}">
+			<ItemsControl.ItemTemplate>
+				<DataTemplate x:DataType="vm:DecompilerSettingsGroupViewModel">
+					<Expander Header="{Binding Category}" IsExpanded="True" Margin="0,2">
+						<ItemsControl ItemsSource="{Binding Settings}" Margin="12,4,0,0">
+							<ItemsControl.ItemTemplate>
+								<DataTemplate x:DataType="vm:DecompilerSettingsItemViewModel">
+									<CheckBox IsChecked="{Binding IsEnabled, Mode=TwoWay}"
+									          Content="{Binding Description}"
+									          Margin="0,1" />
+								</DataTemplate>
+							</ItemsControl.ItemTemplate>
+						</ItemsControl>
+					</Expander>
+				</DataTemplate>
+			</ItemsControl.ItemTemplate>
+		</ItemsControl>
+	</ScrollViewer>
+</UserControl>

ILSpy/Options/DecompilerSettingsPanel.axaml.cs

@@ -0,0 +1,33 @@
+// Copyright (c) 2026 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 global::Avalonia.Controls;
+using global::Avalonia.Markup.Xaml;
+
+namespace ILSpy.Options.Panels
+{
+	public partial class DecompilerSettingsPanel : UserControl
+	{
+		public DecompilerSettingsPanel()
+		{
+			InitializeComponent();
+		}
+
+		void InitializeComponent() => AvaloniaXamlLoader.Load(this);
+	}
+}

ILSpy/Options/DecompilerSettingsViewModel.cs

@@ -0,0 +1,169 @@
+// Copyright (c) 2026 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.Collections.Generic;
+using System.ComponentModel;
+using System.Composition;
+using System.Linq;
+using System.Reflection;
+
+using CommunityToolkit.Mvvm.ComponentModel;
+
+using ICSharpCode.ILSpy.Properties;
+using ICSharpCode.ILSpyX.Settings;
+
+using ILSpy.TreeNodes;
+
+// `Decompiler` short-form alias keeps the reflection-walk over `Decompiler.DecompilerSettings`
+// terse and disambiguates from the ILSpyX `DecompilerSettings` wrapper imported just below.
+using Decompiler = ICSharpCode.Decompiler;
+
+namespace ILSpy.Options
+{
+	/// <summary>
+	/// Reflection-driven viewmodel for the Decompiler-settings panel. Walks every
+	/// non-[Browsable(false)] property on <see cref="Decompiler.DecompilerSettings"/>,
+	/// groups them by their [Category] attribute, and surfaces each as an
+	/// <see cref="DecompilerSettingsItemViewModel"/> with a localised description.
+	/// </summary>
+	// No [Shared] — each Options tab open gets a fresh viewmodel instance bound to a fresh
+	// snapshot. WPF's [NonShared] from TomsToolbox; in System.Composition the absence of
+	// [Shared] gives the same per-call instantiation.
+	[ExportOptionPage(Order = 10)]
+	public sealed partial class DecompilerSettingsViewModel : ObservableObject, IOptionPage
+	{
+		static readonly PropertyInfo[] propertyInfos = typeof(Decompiler.DecompilerSettings).GetProperties()
+			.Where(p => p.GetCustomAttribute<BrowsableAttribute>()?.Browsable != false)
+			.ToArray();
+
+		public string Title => Resources.Decompiler;
+
+		[ObservableProperty]
+		DecompilerSettingsGroupViewModel[] settings = System.Array.Empty<DecompilerSettingsGroupViewModel>();
+
+		DecompilerSettings decompilerSettings = null!;
+
+		public void Load(SettingsSnapshot snapshot)
+		{
+			decompilerSettings = snapshot.GetSettings<DecompilerSettings>();
+			LoadSettings();
+		}
+
+		void LoadSettings()
+		{
+			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 LoadDefaults()
+		{
+			var defaults = new Decompiler.DecompilerSettings();
+			foreach (var p in propertyInfos)
+				p.SetValue(decompilerSettings, p.GetValue(defaults));
+			LoadSettings();
+		}
+	}
+
+	/// <summary>One Category section in the Decompiler panel. Surfaces a tri-state header
+	/// checkbox (all/none/some) that bulk-toggles every item under it.</summary>
+	public sealed partial class DecompilerSettingsGroupViewModel : ObservableObject
+	{
+		[ObservableProperty]
+		bool? areAllItemsChecked;
+
+		public DecompilerSettingsGroupViewModel(string category, DecompilerSettingsItemViewModel[] settings)
+		{
+			Settings = settings;
+			Category = category;
+			areAllItemsChecked = GetAreAllItemsChecked(Settings);
+			foreach (var s in settings)
+				s.PropertyChanged += ItemPropertyChanged;
+		}
+
+		public string Category { get; }
+
+		public DecompilerSettingsItemViewModel[] Settings { get; }
+
+		partial void OnAreAllItemsCheckedChanged(bool? value)
+		{
+			if (!value.HasValue)
+				return;
+			foreach (var s in Settings)
+				s.IsEnabled = value.Value;
+		}
+
+		void ItemPropertyChanged(object? sender, PropertyChangedEventArgs e)
+		{
+			if (e.PropertyName == nameof(DecompilerSettingsItemViewModel.IsEnabled))
+				AreAllItemsChecked = GetAreAllItemsChecked(Settings);
+		}
+
+		static bool? GetAreAllItemsChecked(ICollection<DecompilerSettingsItemViewModel> settings)
+		{
+			var enabled = settings.Count(i => i.IsEnabled);
+			if (enabled == settings.Count)
+				return true;
+			if (enabled == 0)
+				return false;
+			return null;
+		}
+	}
+
+	/// <summary>One reflection-discovered boolean setting in the Decompiler panel.</summary>
+	public sealed partial class DecompilerSettingsItemViewModel : ObservableObject
+	{
+		readonly PropertyInfo property;
+		readonly DecompilerSettings settings;
+
+		public DecompilerSettingsItemViewModel(PropertyInfo property, DecompilerSettings settings)
+		{
+			this.property = property;
+			this.settings = settings;
+			isEnabled = property.GetValue(settings) is true;
+			Description = GetResourceString(property.GetCustomAttribute<DescriptionAttribute>()?.Description ?? property.Name);
+			Category = GetResourceString(property.GetCustomAttribute<CategoryAttribute>()?.Category ?? Resources.Other);
+		}
+
+		[ObservableProperty]
+		bool isEnabled;
+
+		/// <summary>The <see cref="Decompiler.DecompilerSettings"/> property this item
+		/// reflects. Exposed for tests that need to look up an item by name.</summary>
+		public PropertyInfo Property => property;
+
+		public string Description { get; }
+
+		public string Category { get; }
+
+		partial void OnIsEnabledChanged(bool value)
+		{
+			property.SetValue(settings, value);
+		}
+
+		static string GetResourceString(string key)
+		{
+			var str = !string.IsNullOrEmpty(key) ? Resources.ResourceManager.GetString(key) : null;
+			return string.IsNullOrEmpty(key) || string.IsNullOrEmpty(str) ? key : str;
+		}
+	}
+
+}

ILSpy/Options/DisplaySettings.cs

@@ -0,0 +1,158 @@
+// Copyright (c) 2026 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.Xml.Linq;
+
+using CommunityToolkit.Mvvm.ComponentModel;
+
+using ICSharpCode.ILSpyX.Settings;
+
+namespace ILSpy.Options
+{
+	/// <summary>
+	/// Editor-and-tree visual preferences. Persisted under the <c>&lt;DisplaySettings/&gt;</c>
+	/// XML section; the schema matches the WPF host so saved settings round-trip across
+	/// platforms. Font family is a string (Avalonia's <see cref="global::Avalonia.Media.FontFamily"/>
+	/// is constructed from a name at consumption sites — no WPF FontFamily here so this type
+	/// stays UI-framework-free).
+	/// </summary>
+	public sealed partial class DisplaySettings : ObservableObject, ISettingsSection
+	{
+		[ObservableProperty]
+		string selectedFont = "Consolas";
+
+		[ObservableProperty]
+		double selectedFontSize = 10.0 * 4 / 3;
+
+		[ObservableProperty]
+		bool showLineNumbers;
+
+		[ObservableProperty]
+		bool showMetadataTokens;
+
+		[ObservableProperty]
+		bool showMetadataTokensInBase10;
+
+		[ObservableProperty]
+		bool enableWordWrap;
+
+		[ObservableProperty]
+		bool sortResults = true;
+
+		[ObservableProperty]
+		bool foldBraces;
+
+		[ObservableProperty]
+		bool expandMemberDefinitions;
+
+		[ObservableProperty]
+		bool expandUsingDeclarations;
+
+		[ObservableProperty]
+		bool showDebugInfo;
+
+		[ObservableProperty]
+		bool indentationUseTabs = true;
+
+		[ObservableProperty]
+		int indentationTabSize = 4;
+
+		[ObservableProperty]
+		int indentationSize = 4;
+
+		[ObservableProperty]
+		bool highlightMatchingBraces = true;
+
+		[ObservableProperty]
+		bool highlightCurrentLine;
+
+		[ObservableProperty]
+		bool hideEmptyMetadataTables = true;
+
+		[ObservableProperty]
+		bool useNestedNamespaceNodes;
+
+		[ObservableProperty]
+		bool styleWindowTitleBar;
+
+		[ObservableProperty]
+		bool showRawOffsetsAndBytesBeforeInstruction;
+
+		[ObservableProperty]
+		bool enableSmoothScrolling = true;
+
+		[ObservableProperty]
+		bool decodeCustomAttributeBlobs;
+
+		public XName SectionName => "DisplaySettings";
+
+		public void LoadFromXml(XElement section)
+		{
+			SelectedFont = (string?)section.Attribute("Font") ?? "Consolas";
+			SelectedFontSize = (double?)section.Attribute("FontSize") ?? 10.0 * 4 / 3;
+			ShowLineNumbers = (bool?)section.Attribute(nameof(ShowLineNumbers)) ?? false;
+			ShowMetadataTokens = (bool?)section.Attribute(nameof(ShowMetadataTokens)) ?? false;
+			ShowMetadataTokensInBase10 = (bool?)section.Attribute(nameof(ShowMetadataTokensInBase10)) ?? false;
+			ShowDebugInfo = (bool?)section.Attribute(nameof(ShowDebugInfo)) ?? false;
+			EnableWordWrap = (bool?)section.Attribute(nameof(EnableWordWrap)) ?? false;
+			SortResults = (bool?)section.Attribute(nameof(SortResults)) ?? true;
+			FoldBraces = (bool?)section.Attribute(nameof(FoldBraces)) ?? false;
+			ExpandMemberDefinitions = (bool?)section.Attribute(nameof(ExpandMemberDefinitions)) ?? false;
+			ExpandUsingDeclarations = (bool?)section.Attribute(nameof(ExpandUsingDeclarations)) ?? false;
+			IndentationUseTabs = (bool?)section.Attribute(nameof(IndentationUseTabs)) ?? true;
+			IndentationSize = (int?)section.Attribute(nameof(IndentationSize)) ?? 4;
+			IndentationTabSize = (int?)section.Attribute(nameof(IndentationTabSize)) ?? 4;
+			HighlightMatchingBraces = (bool?)section.Attribute(nameof(HighlightMatchingBraces)) ?? true;
+			HighlightCurrentLine = (bool?)section.Attribute(nameof(HighlightCurrentLine)) ?? false;
+			HideEmptyMetadataTables = (bool?)section.Attribute(nameof(HideEmptyMetadataTables)) ?? true;
+			UseNestedNamespaceNodes = (bool?)section.Attribute(nameof(UseNestedNamespaceNodes)) ?? false;
+			ShowRawOffsetsAndBytesBeforeInstruction = (bool?)section.Attribute(nameof(ShowRawOffsetsAndBytesBeforeInstruction)) ?? false;
+			StyleWindowTitleBar = (bool?)section.Attribute(nameof(StyleWindowTitleBar)) ?? false;
+			EnableSmoothScrolling = (bool?)section.Attribute(nameof(EnableSmoothScrolling)) ?? true;
+			DecodeCustomAttributeBlobs = (bool?)section.Attribute(nameof(DecodeCustomAttributeBlobs)) ?? false;
+		}
+
+		public XElement SaveToXml()
+		{
+			var section = new XElement(SectionName);
+			section.SetAttributeValue("Font", SelectedFont);
+			section.SetAttributeValue("FontSize", SelectedFontSize);
+			section.SetAttributeValue(nameof(ShowLineNumbers), ShowLineNumbers);
+			section.SetAttributeValue(nameof(ShowMetadataTokens), ShowMetadataTokens);
+			section.SetAttributeValue(nameof(ShowMetadataTokensInBase10), ShowMetadataTokensInBase10);
+			section.SetAttributeValue(nameof(ShowDebugInfo), ShowDebugInfo);
+			section.SetAttributeValue(nameof(EnableWordWrap), EnableWordWrap);
+			section.SetAttributeValue(nameof(SortResults), SortResults);
+			section.SetAttributeValue(nameof(FoldBraces), FoldBraces);
+			section.SetAttributeValue(nameof(ExpandMemberDefinitions), ExpandMemberDefinitions);
+			section.SetAttributeValue(nameof(ExpandUsingDeclarations), ExpandUsingDeclarations);
+			section.SetAttributeValue(nameof(IndentationUseTabs), IndentationUseTabs);
+			section.SetAttributeValue(nameof(IndentationSize), IndentationSize);
+			section.SetAttributeValue(nameof(IndentationTabSize), IndentationTabSize);
+			section.SetAttributeValue(nameof(HighlightMatchingBraces), HighlightMatchingBraces);
+			section.SetAttributeValue(nameof(HighlightCurrentLine), HighlightCurrentLine);
+			section.SetAttributeValue(nameof(HideEmptyMetadataTables), HideEmptyMetadataTables);
+			section.SetAttributeValue(nameof(UseNestedNamespaceNodes), UseNestedNamespaceNodes);
+			section.SetAttributeValue(nameof(ShowRawOffsetsAndBytesBeforeInstruction), ShowRawOffsetsAndBytesBeforeInstruction);
+			section.SetAttributeValue(nameof(StyleWindowTitleBar), StyleWindowTitleBar);
+			section.SetAttributeValue(nameof(EnableSmoothScrolling), EnableSmoothScrolling);
+			section.SetAttributeValue(nameof(DecodeCustomAttributeBlobs), DecodeCustomAttributeBlobs);
+			return section;
+		}
+	}
+}

ILSpy/Options/DisplaySettingsPanel.axaml

@@ -0,0 +1,94 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:vm="using:ILSpy.Options"
+             xmlns:res="using:ICSharpCode.ILSpy.Properties"
+             mc:Ignorable="d" d:DesignWidth="700" d:DesignHeight="500"
+             x:Class="ILSpy.Options.Panels.DisplaySettingsPanel"
+             x:DataType="vm:DisplaySettingsViewModel">
+	<ScrollViewer Padding="6">
+		<StackPanel Spacing="10">
+			<Grid ColumnDefinitions="Auto,*,Auto" RowDefinitions="Auto,Auto" ColumnSpacing="8" RowSpacing="4">
+				<TextBlock Grid.Row="0" Grid.Column="0" VerticalAlignment="Center"
+				           Text="{x:Static res:Resources.Font}" />
+				<ComboBox Grid.Row="0" Grid.Column="1" MinWidth="200"
+				          ItemsSource="{Binding AvailableFonts}"
+				          SelectedItem="{Binding Settings.SelectedFont, Mode=TwoWay}" />
+				<NumericUpDown Grid.Row="0" Grid.Column="2" Width="100"
+				               Minimum="6" Maximum="72" Increment="1"
+				               Value="{Binding Settings.SelectedFontSize, Mode=TwoWay}" />
+				<Border Grid.Row="1" Grid.Column="1" Grid.ColumnSpan="2"
+				        BorderBrush="#FFCCCEDB" BorderThickness="1" Padding="6" Margin="0,2,0,0">
+					<TextBlock Text="The quick brown fox jumps over the lazy dog"
+					           FontFamily="{Binding Settings.SelectedFont}"
+					           FontSize="{Binding Settings.SelectedFontSize}" />
+				</Border>
+			</Grid>
+
+			<HeaderedContentControl Header="{x:Static res:Resources.Indentation}">
+				<StackPanel Spacing="4" Margin="12,4,0,0">
+					<CheckBox IsChecked="{Binding Settings.IndentationUseTabs, Mode=TwoWay}"
+					          Content="{x:Static res:Resources.UseTabsInsteadOfSpaces}" />
+					<Grid ColumnDefinitions="Auto,Auto,Auto,Auto" ColumnSpacing="6">
+						<TextBlock Grid.Column="0" VerticalAlignment="Center"
+						           Text="{x:Static res:Resources.IndentSize}" />
+						<NumericUpDown Grid.Column="1" Width="80" Minimum="1" Maximum="16"
+						               Value="{Binding Settings.IndentationSize, Mode=TwoWay}" />
+						<TextBlock Grid.Column="2" VerticalAlignment="Center" Margin="12,0,0,0"
+						           Text="{x:Static res:Resources.TabSize}" />
+						<NumericUpDown Grid.Column="3" Width="80" Minimum="1" Maximum="16"
+						               Value="{Binding Settings.IndentationTabSize, Mode=TwoWay}" />
+					</Grid>
+				</StackPanel>
+			</HeaderedContentControl>
+
+			<HeaderedContentControl Header="{x:Static res:Resources.DecompilationViewOptions}">
+				<StackPanel Spacing="2" Margin="12,4,0,0">
+					<CheckBox IsChecked="{Binding Settings.ShowLineNumbers, Mode=TwoWay}"
+					          Content="{x:Static res:Resources.ShowLineNumbers}" />
+					<CheckBox IsChecked="{Binding Settings.EnableWordWrap, Mode=TwoWay}"
+					          Content="{x:Static res:Resources.EnableWordWrap}" />
+					<CheckBox IsChecked="{Binding Settings.FoldBraces, Mode=TwoWay}"
+					          Content="{x:Static res:Resources.EnableFoldingBlocksBraces}" />
+					<CheckBox IsChecked="{Binding Settings.HighlightMatchingBraces, Mode=TwoWay}"
+					          Content="{x:Static res:Resources.HighlightMatchingBraces}" />
+					<CheckBox IsChecked="{Binding Settings.HighlightCurrentLine, Mode=TwoWay}"
+					          Content="{x:Static res:Resources.HighlightCurrentLine}" />
+					<CheckBox IsChecked="{Binding Settings.ExpandMemberDefinitions, Mode=TwoWay}"
+					          Content="{x:Static res:Resources.ExpandMemberDefinitionsAfterDecompilation}" />
+					<CheckBox IsChecked="{Binding Settings.ExpandUsingDeclarations, Mode=TwoWay}"
+					          Content="{x:Static res:Resources.ExpandUsingDeclarationsAfterDecompilation}" />
+					<CheckBox IsChecked="{Binding Settings.ShowDebugInfo, Mode=TwoWay}"
+					          Content="{x:Static res:Resources.ShowInfoFromDebugSymbolsAvailable}" />
+					<CheckBox IsChecked="{Binding Settings.ShowRawOffsetsAndBytesBeforeInstruction, Mode=TwoWay}"
+					          Content="{x:Static res:Resources.ShowRawOffsetsAndBytesBeforeInstruction}" />
+					<CheckBox IsChecked="{Binding Settings.DecodeCustomAttributeBlobs, Mode=TwoWay}"
+					          Content="{x:Static res:Resources.DecodeCustomAttributeBlobs}" />
+					<CheckBox IsChecked="{Binding Settings.EnableSmoothScrolling, Mode=TwoWay}"
+					          Content="{x:Static res:Resources.EnableSmoothScrolling}" />
+				</StackPanel>
+			</HeaderedContentControl>
+
+			<HeaderedContentControl Header="{x:Static res:Resources.TreeViewOptions}">
+				<StackPanel Spacing="2" Margin="12,4,0,0">
+					<CheckBox IsChecked="{Binding Settings.ShowMetadataTokens, Mode=TwoWay}"
+					          Content="{x:Static res:Resources.ShowMetadataTokens}" />
+					<CheckBox IsChecked="{Binding Settings.ShowMetadataTokensInBase10, Mode=TwoWay}"
+					          Content="{x:Static res:Resources.ShowMetadataTokensInBase10}" />
+					<CheckBox IsChecked="{Binding Settings.HideEmptyMetadataTables, Mode=TwoWay}"
+					          Content="{x:Static res:Resources.HideEmptyMetadataTables}" />
+					<CheckBox IsChecked="{Binding Settings.UseNestedNamespaceNodes, Mode=TwoWay}"
+					          Content="{x:Static res:Resources.UseNestedNamespaceNodes}" />
+				</StackPanel>
+			</HeaderedContentControl>
+
+			<HeaderedContentControl Header="{x:Static res:Resources.Other}">
+				<StackPanel Spacing="2" Margin="12,4,0,0">
+					<CheckBox IsChecked="{Binding Settings.SortResults, Mode=TwoWay}"
+					          Content="{x:Static res:Resources.SortResultsFitness}" />
+				</StackPanel>
+			</HeaderedContentControl>
+		</StackPanel>
+	</ScrollViewer>
+</UserControl>

ILSpy/Options/DisplaySettingsPanel.axaml.cs

@@ -0,0 +1,33 @@
+// Copyright (c) 2026 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 global::Avalonia.Controls;
+using global::Avalonia.Markup.Xaml;
+
+namespace ILSpy.Options.Panels
+{
+	public partial class DisplaySettingsPanel : UserControl
+	{
+		public DisplaySettingsPanel()
+		{
+			InitializeComponent();
+		}
+
+		void InitializeComponent() => AvaloniaXamlLoader.Load(this);
+	}
+}

ILSpy/Options/DisplaySettingsViewModel.cs

@@ -0,0 +1,62 @@
+// Copyright (c) 2026 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.Collections.Generic;
+using System.Linq;
+using System.Xml.Linq;
+
+using global::Avalonia.Media;
+
+using CommunityToolkit.Mvvm.ComponentModel;
+
+using ICSharpCode.ILSpy.Properties;
+
+namespace ILSpy.Options
+{
+	/// <summary>Viewmodel for the Display panel. Exposes the snapshot's
+	/// <see cref="DisplaySettings"/> through <see cref="Settings"/> for direct two-way
+	/// binding in the panel view, plus the list of system font families for the picker.</summary>
+	[ExportOptionPage(Order = 20)]
+	public sealed partial class DisplaySettingsViewModel : ObservableObject, IOptionPage
+	{
+		public string Title => Resources.Display;
+
+		[ObservableProperty]
+		DisplaySettings settings = null!;
+
+		// Avalonia equivalent of WPF's Fonts.SystemFontFamilies. FontManager.Current populates
+		// from the platform font enumerator (DirectWrite on Windows, FontConfig on Linux,
+		// CoreText on macOS), so the list is realistic on every supported target.
+		public IReadOnlyList<string> AvailableFonts { get; } = FontManager.Current.SystemFonts
+			.Select(t => t.Name)
+			.OrderBy(n => n, System.StringComparer.OrdinalIgnoreCase)
+			.ToArray();
+
+		public void Load(SettingsSnapshot snapshot)
+		{
+			Settings = snapshot.GetSettings<DisplaySettings>();
+		}
+
+		public void LoadDefaults()
+		{
+			// Reset by replaying LoadFromXml against an empty element — every attribute is
+			// absent so each property falls back to its built-in default.
+			Settings.LoadFromXml(new XElement("DisplaySettings"));
+		}
+	}
+}

ILSpy/Options/ExportOptionPageAttribute.cs

@@ -0,0 +1,39 @@
+// Copyright (c) 2026 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.Composition;
+
+namespace ILSpy.Options
+{
+	/// <summary>
+	/// Marks a class as an Options-tab panel. MEF discovers all such exports under the
+	/// shared contract "OptionPages" with metadata <see cref="IOptionsMetadata"/>; the
+	/// Options host orders them by <see cref="Order"/> and renders them as inner tabs.
+	/// </summary>
+	[MetadataAttribute]
+	[AttributeUsage(AttributeTargets.Class)]
+	public sealed class ExportOptionPageAttribute() : ExportAttribute("OptionPages", typeof(IOptionPage))
+	{
+		// Public property is reflected by System.Composition into the IOptionsMetadata
+		// metadata view (matched by name). The metadata view is a concrete class in this
+		// MEF host, so there's no "implements IOptionsMetadata" — the wire-up is purely
+		// nominal property matching.
+		public int Order { get; set; }
+	}
+}

ILSpy/Options/IOptionPage.cs

@@ -0,0 +1,35 @@
+// Copyright (c) 2026 AlphaSierraPapa for the SharpDevelop Team
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+namespace ILSpy.Options
+{
+	/// <summary>
+	/// Plugin contract for individual panels in the Options tab. Each implementation is
+	/// MEF-discovered via <see cref="ExportOptionPageAttribute"/>; the host calls
+	/// <see cref="Load"/> with a snapshot of the current settings when the tab opens, and
+	/// <see cref="LoadDefaults"/> when the user clicks the per-panel reset button.
+	/// </summary>
+	public interface IOptionPage
+	{
+		string Title { get; }
+
+		void Load(SettingsSnapshot settings);
+
+		void LoadDefaults();
+	}
+}

ILSpy/Options/IOptionsMetadata.cs

@@ -0,0 +1,33 @@
+// Copyright (c) 2026 AlphaSierraPapa for the SharpDevelop Team
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+namespace ILSpy.Options
+{
+	/// <summary>
+	/// Strongly-typed metadata view for <see cref="IOptionPage"/> exports — <see cref="Order"/>
+	/// drives the tab order inside the Options page (lowest first). Concrete class with a
+	/// parameterless constructor because System.Composition (MEF2) requires that for
+	/// metadata views — the WPF host's same-named interface doesn't translate. The "I"
+	/// prefix is kept to mirror the WPF naming so the call sites read identically across
+	/// platforms.
+	/// </summary>
+	public sealed class IOptionsMetadata
+	{
+		public int Order { get; set; }
+	}
+}

ILSpy/Options/MiscSettings.cs

@@ -0,0 +1,56 @@
+// Copyright (c) 2026 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.Xml.Linq;
+
+using CommunityToolkit.Mvvm.ComponentModel;
+
+using ICSharpCode.ILSpyX.Settings;
+
+namespace ILSpy.Options
+{
+	/// <summary>
+	/// Cross-cutting application-level toggles that don't fit Decompiler or Display.
+	/// Persisted under the <c>&lt;MiscSettings/&gt;</c> XML section; XML attribute names
+	/// and defaults match the WPF host so saved settings round-trip across platforms.
+	/// </summary>
+	public sealed partial class MiscSettings : ObservableObject, ISettingsSection
+	{
+		[ObservableProperty]
+		bool allowMultipleInstances;
+
+		[ObservableProperty]
+		bool loadPreviousAssemblies = true;
+
+		public XName SectionName => "MiscSettings";
+
+		public void LoadFromXml(XElement e)
+		{
+			AllowMultipleInstances = (bool?)e.Attribute(nameof(AllowMultipleInstances)) ?? false;
+			LoadPreviousAssemblies = (bool?)e.Attribute(nameof(LoadPreviousAssemblies)) ?? true;
+		}
+
+		public XElement SaveToXml()
+		{
+			var section = new XElement(SectionName);
+			section.SetAttributeValue(nameof(AllowMultipleInstances), AllowMultipleInstances);
+			section.SetAttributeValue(nameof(LoadPreviousAssemblies), LoadPreviousAssemblies);
+			return section;
+		}
+	}
+}

ILSpy/Options/MiscSettingsPanel.axaml

@@ -0,0 +1,16 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:vm="using:ILSpy.Options"
+             xmlns:res="using:ICSharpCode.ILSpy.Properties"
+             mc:Ignorable="d" d:DesignWidth="500" d:DesignHeight="300"
+             x:Class="ILSpy.Options.Panels.MiscSettingsPanel"
+             x:DataType="vm:MiscSettingsViewModel">
+	<StackPanel Spacing="6" Margin="6">
+		<CheckBox IsChecked="{Binding Settings.AllowMultipleInstances, Mode=TwoWay}"
+		          Content="{x:Static res:Resources.AllowMultipleInstances}" />
+		<CheckBox IsChecked="{Binding Settings.LoadPreviousAssemblies, Mode=TwoWay}"
+		          Content="Load previously open assemblies on startup" />
+	</StackPanel>
+</UserControl>

ILSpy/Options/MiscSettingsPanel.axaml.cs

@@ -0,0 +1,33 @@
+// Copyright (c) 2026 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 global::Avalonia.Controls;
+using global::Avalonia.Markup.Xaml;
+
+namespace ILSpy.Options.Panels
+{
+	public partial class MiscSettingsPanel : UserControl
+	{
+		public MiscSettingsPanel()
+		{
+			InitializeComponent();
+		}
+
+		void InitializeComponent() => AvaloniaXamlLoader.Load(this);
+	}
+}

ILSpy/Options/MiscSettingsViewModel.cs

@@ -0,0 +1,48 @@
+// Copyright (c) 2026 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.Xml.Linq;
+
+using CommunityToolkit.Mvvm.ComponentModel;
+
+using ICSharpCode.ILSpy.Properties;
+
+namespace ILSpy.Options
+{
+	/// <summary>Viewmodel for the Misc panel. WPF additionally exposes a shell-integration
+	/// command (Add/Remove "Open with ILSpy" registry keys); deferred for v1 since
+	/// Avalonia's WinExe doesn't register file associations yet.</summary>
+	[ExportOptionPage(Order = 30)]
+	public sealed partial class MiscSettingsViewModel : ObservableObject, IOptionPage
+	{
+		public string Title => Resources.Misc;
+
+		[ObservableProperty]
+		MiscSettings settings = null!;
+
+		public void Load(SettingsSnapshot snapshot)
+		{
+			Settings = snapshot.GetSettings<MiscSettings>();
+		}
+
+		public void LoadDefaults()
+		{
+			Settings.LoadFromXml(new XElement("MiscSettings"));
+		}
+	}
+}

ILSpy/Options/OptionsPageModel.cs

@@ -0,0 +1,78 @@
+// Copyright (c) 2026 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.Collections.Generic;
+using System.Composition;
+using System.Linq;
+
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+
+using ICSharpCode.ILSpy.Properties;
+
+namespace ILSpy.Options
+{
+	/// <summary>
+	/// Content viewmodel for the Options document tab. Wraps a <see cref="SettingsSnapshot"/>,
+	/// MEF-discovered <see cref="IOptionPage"/> panels (ordered by <see cref="IOptionsMetadata.Order"/>),
+	/// and the page-level Apply / Reset commands the panel views bind to.
+	/// </summary>
+	public sealed partial class OptionsPageModel : ObservableObject
+	{
+		readonly SettingsSnapshot snapshot;
+
+		public OptionsPageModel(SettingsService settingsService, IEnumerable<ExportFactory<IOptionPage, IOptionsMetadata>> pageFactories)
+		{
+			snapshot = settingsService.CreateSnapshot();
+
+			Pages = pageFactories
+				.OrderBy(f => f.Metadata.Order)
+				.Select(f => f.CreateExport().Value)
+				.ToArray();
+
+			foreach (var page in Pages)
+				page.Load(snapshot);
+
+			selectedPage = Pages.FirstOrDefault();
+			Title = Resources._Options;
+
+			ApplyCommand = new RelayCommand(Apply);
+			ResetCurrentPageCommand = new RelayCommand(ResetCurrentPage);
+		}
+
+		public string Title { get; }
+
+		/// <summary>Marker for the dock router: tree-node selections must not replace this
+		/// tab. Mirrors the <see cref="ILSpy.TextView.DecompilerTabPageModel.IsStaticContent"/>
+		/// convention used for the About tab.</summary>
+		public bool IsStaticContent => true;
+
+		public IReadOnlyList<IOptionPage> Pages { get; }
+
+		[ObservableProperty]
+		IOptionPage? selectedPage;
+
+		public IRelayCommand ApplyCommand { get; }
+
+		public IRelayCommand ResetCurrentPageCommand { get; }
+
+		void Apply() => snapshot.Save();
+
+		void ResetCurrentPage() => SelectedPage?.LoadDefaults();
+	}
+}

ILSpy/Options/OptionsPageView.axaml

@@ -0,0 +1,50 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:vm="using:ILSpy.Options"
+             xmlns:panels="using:ILSpy.Options.Panels"
+             xmlns:res="using:ICSharpCode.ILSpy.Properties"
+             mc:Ignorable="d" d:DesignWidth="700" d:DesignHeight="500"
+             x:Class="ILSpy.Options.OptionsPageView"
+             x:DataType="vm:OptionsPageModel">
+	<DockPanel LastChildFill="True">
+		<!-- Apply / Reset live in the page footer rather than per-panel. Functionally
+		     identical to a per-panel Apply (every Apply commits the full snapshot);
+		     keeps the buttons accessible regardless of which inner tab is active and
+		     avoids parent-binding gymnastics from inside each panel's DataContext. -->
+		<Border DockPanel.Dock="Bottom" BorderBrush="#FFC8CDD3" BorderThickness="0,1,0,0" Padding="8">
+			<StackPanel Orientation="Horizontal" HorizontalAlignment="Right" Spacing="6">
+				<Button Content="{x:Static res:Resources.ResetToDefaults}"
+				        Command="{Binding ResetCurrentPageCommand}" />
+				<Button Content="{x:Static res:Resources.OK}"
+				        Command="{Binding ApplyCommand}" />
+			</StackPanel>
+		</Border>
+		<TabControl ItemsSource="{Binding Pages}"
+		            SelectedItem="{Binding SelectedPage, Mode=TwoWay}">
+			<TabControl.ItemTemplate>
+				<DataTemplate x:DataType="vm:IOptionPage">
+					<TextBlock Text="{Binding Title}" />
+				</DataTemplate>
+			</TabControl.ItemTemplate>
+			<TabControl.ContentTemplate>
+				<DataTemplate>
+					<ContentControl Content="{Binding}">
+						<ContentControl.DataTemplates>
+							<DataTemplate x:DataType="vm:DecompilerSettingsViewModel">
+								<panels:DecompilerSettingsPanel />
+							</DataTemplate>
+							<DataTemplate x:DataType="vm:DisplaySettingsViewModel">
+								<panels:DisplaySettingsPanel />
+							</DataTemplate>
+							<DataTemplate x:DataType="vm:MiscSettingsViewModel">
+								<panels:MiscSettingsPanel />
+							</DataTemplate>
+						</ContentControl.DataTemplates>
+					</ContentControl>
+				</DataTemplate>
+			</TabControl.ContentTemplate>
+		</TabControl>
+	</DockPanel>
+</UserControl>

ILSpy/Options/OptionsPageView.axaml.cs

@@ -0,0 +1,33 @@
+// Copyright (c) 2026 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 global::Avalonia.Controls;
+using global::Avalonia.Markup.Xaml;
+
+namespace ILSpy.Options
+{
+	public partial class OptionsPageView : UserControl
+	{
+		public OptionsPageView()
+		{
+			InitializeComponent();
+		}
+
+		void InitializeComponent() => AvaloniaXamlLoader.Load(this);
+	}
+}

ILSpy/Options/SettingsSnapshot.cs

@@ -0,0 +1,55 @@
+// Copyright (c) 2026 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 ICSharpCode.ILSpyX;
+using ICSharpCode.ILSpyX.Settings;
+
+namespace ILSpy.Options
+{
+	/// <summary>
+	/// In-memory copy of the persisted settings, used by the Options tab so panel edits
+	/// don't reach the live <see cref="ILSpy.SettingsService"/> until the user
+	/// clicks Apply. Inherits the standard <see cref="SettingsServiceBase.GetSettings{T}"/>
+	/// load+subscribe machinery from the shared base — sections materialise on first
+	/// access reading from the same XML root as the parent service, but are independent
+	/// object graphs. <see cref="Save"/> writes those graphs back through the parent's
+	/// <see cref="ISettingsProvider"/> and asks the parent to reload so subscribers see
+	/// the new values.
+	/// </summary>
+	public sealed class SettingsSnapshot : SettingsServiceBase
+	{
+		readonly SettingsService parent;
+
+		public SettingsSnapshot(SettingsService parent, ISettingsProvider spySettings) : base(spySettings)
+		{
+			this.parent = parent;
+		}
+
+		public void Save()
+		{
+			SpySettings.Update(root => {
+				foreach (var section in sections.Values)
+				{
+					SaveSection(section, root);
+				}
+			});
+
+			parent.Reload();
+		}
+	}
+}

ILSpy/SettingsService.cs

@@ -16,11 +16,14 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
+using System;
 using System.Composition;
 
 using ICSharpCode.ILSpyX;
 using ICSharpCode.ILSpyX.Settings;
 
+using ILSpy.Options;
+
 namespace ILSpy
 {
 	[Export]
@@ -33,12 +36,49 @@ namespace ILSpy
 
 		public SessionSettings SessionSettings => GetSettings<SessionSettings>();
 
+		public DecompilerSettings DecompilerSettings => GetSettings<DecompilerSettings>();
+
+		public DisplaySettings DisplaySettings => GetSettings<DisplaySettings>();
+
+		public MiscSettings MiscSettings => GetSettings<MiscSettings>();
+
 		AssemblyListManager? assemblyListManager;
 		public AssemblyListManager AssemblyListManager => assemblyListManager ??= new(SpySettings);
 
+		/// <summary>Fired after <see cref="Reload"/> propagates fresh values from disk into the
+		/// live section instances. Subscribers (e.g. the assembly tree, the decompiler view)
+		/// observe this to refresh derived UI state.</summary>
+		public event EventHandler? SettingsChanged;
+
+		/// <summary>
+		/// Creates a parallel <see cref="SettingsSnapshot"/> bound to the same XML root. The
+		/// snapshot returns fresh, independent section instances on first access — Options
+		/// panels mutate those copies so the live service stays untouched until
+		/// <see cref="SettingsSnapshot.Save"/>.
+		/// </summary>
+		public SettingsSnapshot CreateSnapshot() => new(this, SpySettings);
+
+		/// <summary>
+		/// Reloads every materialised section from <see cref="SpySettings"/>. Called after a
+		/// snapshot commits so the live instances pick up the just-written values without
+		/// rebuilding the dictionary (subscribers see PropertyChanged for every changed field).
+		/// </summary>
+		public void Reload()
+		{
+			foreach (var section in sections.Values)
+			{
+				var element = SpySettings[section.SectionName];
+				section.LoadFromXml(element);
+			}
+			SettingsChanged?.Invoke(this, EventArgs.Empty);
+		}
+
 		public void Save()
 		{
-			SpySettings.Update(root => SaveSection(SessionSettings, root));
+			SpySettings.Update(root => {
+				foreach (var section in sections.Values)
+					SaveSection(section, root);
+			});
 		}
 	}
 }

ILSpy/TextView/DecompilerTabPageModel.cs

@@ -262,9 +262,15 @@ namespace ILSpy.TextView
 
 			try
 			{
+				// Pull a fresh clone of the live DecompilerSettings so Options-panel commits
+				// reach the next decompile without restart. Cloning isolates this run's
+				// settings from concurrent edits in an open Options tab.
+				var decompilerSettings = TryGetLiveDecompilerSettings();
 				var (output, _) = await Task.Run(() => {
 					var output = new AvaloniaEditTextOutput();
-					var options = new DecompilationOptions { CancellationToken = cts.Token };
+					var options = decompilerSettings != null
+						? new DecompilationOptions(decompilerSettings) { CancellationToken = cts.Token }
+						: new DecompilationOptions { CancellationToken = cts.Token };
 					try
 					{
 						for (int i = 0; i < nodes.Count; i++)
@@ -371,5 +377,20 @@ namespace ILSpy.TextView
 				Title = ComposeSpinnerTitle(frame++, ComposeBaseTitle());
 			}
 		}
+
+		// Pulls the live DecompilerSettings via MEF and returns a clone for this run. MEF
+		// resolve is wrapped in try/catch so design-time / minimal test hosts that bypass
+		// composition fall back to default settings rather than throwing.
+		static ICSharpCode.Decompiler.DecompilerSettings? TryGetLiveDecompilerSettings()
+		{
+			try
+			{
+				return AppEnv.AppComposition.Current.GetExport<SettingsService>().DecompilerSettings.Clone();
+			}
+			catch
+			{
+				return null;
+			}
+		}
 	}
 }

ILSpy/Views/ContentTabPageView.axaml

@@ -5,11 +5,12 @@
              xmlns:vm="using:ILSpy.ViewModels"
              xmlns:textView="using:ILSpy.TextView"
              xmlns:metaViews="using:ILSpy.Views"
+             xmlns:options="using:ILSpy.Options"
              mc:Ignorable="d" d:DesignWidth="600" d:DesignHeight="400"
              x:Class="ILSpy.Views.ContentTabPageView"
              x:DataType="vm:ContentTabPage">
 
-	<!-- Both inner views are pre-realised; only the one matching Content's runtime type
+	<!-- All inner views are pre-realised; only the one matching Content's runtime type
 	     is visible. Code-behind toggles IsVisible and DataContext on Content change.
 	     Avoids Dock's add+close-in-the-same-tick visual-staleness when the tab type
 	     changes (the previous view would otherwise stay rendered until the next layout
@@ -17,6 +18,7 @@
 	<Panel>
 		<textView:DecompilerTextView Name="DecompilerView" />
 		<metaViews:MetadataTablePage Name="MetadataView" />
+		<options:OptionsPageView Name="OptionsView" />
 	</Panel>
 
 </UserControl>

ILSpy/Views/ContentTabPageView.axaml.cs

@@ -21,6 +21,7 @@ using System.ComponentModel;
 using Avalonia.Controls;
 using Avalonia.Markup.Xaml;
 
+using ILSpy.Options;
 using ILSpy.TextView;
 using ILSpy.ViewModels;
 
@@ -28,21 +29,23 @@ namespace ILSpy.Views
 {
 	/// <summary>
 	/// View for <see cref="ContentTabPage"/>. Toggles which pre-realised inner view shows
-	/// (decompiler text or metadata grid) based on <see cref="ContentTabPage.Content"/>'s
-	/// runtime type — both inner views live in the visual tree from construction time so
-	/// the dock's visual swap is just a visibility flip.
+	/// (decompiler text, metadata grid, or Options page) based on
+	/// <see cref="ContentTabPage.Content"/>'s runtime type — all inner views live in the
+	/// visual tree from construction time so the dock's visual swap is just a visibility flip.
 	/// </summary>
 	public partial class ContentTabPageView : UserControl
 	{
 		ContentTabPage? boundPage;
 		DecompilerTextView decompilerView = null!;
 		MetadataTablePage metadataView = null!;
+		OptionsPageView optionsView = null!;
 
 		public ContentTabPageView()
 		{
 			InitializeComponent();
 			decompilerView = this.FindControl<DecompilerTextView>("DecompilerView")!;
 			metadataView = this.FindControl<MetadataTablePage>("MetadataView")!;
+			optionsView = this.FindControl<OptionsPageView>("OptionsView")!;
 			DataContextChanged += (_, _) => RebindPage();
 		}
 
@@ -89,6 +92,17 @@ namespace ILSpy.Views
 				metadataView.IsVisible = false;
 				metadataView.DataContext = null;
 			}
+
+			if (content is OptionsPageModel options)
+			{
+				optionsView.DataContext = options;
+				optionsView.IsVisible = true;
+			}
+			else
+			{
+				optionsView.IsVisible = false;
+				optionsView.DataContext = null;
+			}
 		}
 	}
 }