Switch the live assembly list from Manage Assembly Lists

Selecting a list in the dialog only set SessionSettings.ActiveAssemblyList
directly, which merely persists the choice for the next launch — it never
reloaded the tree, so the active list appeared unchanged. Route selection
through AssemblyTreeModel.ActiveListName instead, whose setter reloads the
list (OnActiveListNameChanged -> ShowAssemblyList) and persists the choice.

Also make double-clicking an entry a shortcut for the Select button (both
go through the same activation path).

Assisted-by: Claude:claude-opus-4-8:Claude Code

ILSpy.Tests/AssemblyList/ManageAssemblyListsSelectTests.cs

@@ -0,0 +1,65 @@
+// 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 ILSpy;
+using ILSpy.AppEnv;
+using ILSpy.Views;
+
+using NUnit.Framework;
+
+namespace ICSharpCode.ILSpy.Tests;
+
+/// <summary>
+/// Selecting a list in Manage Assembly Lists (the Select button and the double-click shortcut both
+/// call the same activation path) must switch the LIVE active list, not merely persist it for the
+/// next launch — i.e. it must drive AssemblyTreeModel.ActiveListName, which reloads the tree.
+/// </summary>
+[TestFixture]
+public class ManageAssemblyListsSelectTests
+{
+	[AvaloniaTest]
+	public async Task Selecting_A_List_Switches_The_Live_Active_List()
+	{
+		var (_, vm) = await TestHarness.BootAsync();
+		var settingsService = AppComposition.Current.GetExport<SettingsService>();
+		var manager = settingsService.AssemblyListManager;
+
+		var current = vm.AssemblyTreeModel.ActiveListName;
+
+		// Ensure there is a second, empty list to switch to (the headless fixture seeds one).
+		var other = "Switch Target " + System.Guid.NewGuid().ToString("N");
+		manager.AddListIfNotExists(manager.CreateList(other));
+		other.Should().NotBe(current);
+
+		var dialog = new ManageAssemblyListsDialog(settingsService);
+		dialog.ListsControl.SelectedItem = other;
+		dialog.ActivateSelectedList();
+
+		vm.AssemblyTreeModel.ActiveListName.Should().Be(other,
+			"selecting a list must switch the live active list (via AssemblyTreeModel.ActiveListName), not just the persisted setting");
+		settingsService.SessionSettings.ActiveAssemblyList.Should().Be(other,
+			"and the choice is persisted as a side effect of the model switch");
+	}
+}

ILSpy/Views/ManageAssemblyListsDialog.axaml.cs

@@ -24,7 +24,9 @@ using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 
 using Avalonia.Controls;
+using Avalonia.Input;
 using Avalonia.Markup.Xaml;
+using Avalonia.VisualTree;
 
 using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.ILSpyX;
@@ -73,6 +75,18 @@ namespace ILSpy.Views
 			addPreconfigured.Click += (_, _) => ShowPreconfiguredMenu(addPreconfigured);
 			this.FindControl<Button>("SelectButton")!.Click += (_, _) => SelectAndClose();
 			this.FindControl<Button>("CloseButton")!.Click += (_, _) => Close();
+			// Double-clicking an entry is a shortcut for the Select button: activate that list and
+			// close. Guarded to a real entry so a double-click on empty list space does nothing.
+			listsBox.DoubleTapped += OnListDoubleTapped;
+		}
+
+		void OnListDoubleTapped(object? sender, TappedEventArgs e)
+		{
+			var visual = e.Source as global::Avalonia.Visual;
+			while (visual is not null and not ListBoxItem)
+				visual = visual.GetVisualParent();
+			if (visual is ListBoxItem)
+				SelectAndClose();
 		}
 
 		void ShowPreconfiguredMenu(Button anchor)
@@ -90,6 +104,9 @@ namespace ILSpy.Views
 
 		string? SelectedListName => listsBox.SelectedItem as string;
 
+		/// <summary>The lists control, exposed for tests to drive the selection.</summary>
+		internal ListBox ListsControl => listsBox;
+
 		async Task<string?> PromptAsync(string title, string? initialText = null)
 		{
 			var dlg = new CreateListDialog(title, initialText);
@@ -151,11 +168,24 @@ namespace ILSpy.Views
 
 		void SelectAndClose()
 		{
-			if (SelectedListName is { } selected)
+			ActivateSelectedList();
-				settingsService.SessionSettings.ActiveAssemblyList = selected;
 			Close();
 		}
 
+		/// <summary>
+		/// Switches the live active assembly list to the selected one. Goes through
+		/// <see cref="AssemblyTree.AssemblyTreeModel.ActiveListName"/> rather than poking the
+		/// session setting directly, because that setter is what reloads the tree
+		/// (<c>OnActiveListNameChanged</c> -> <c>ShowAssemblyList</c>) and persists the choice.
+		/// Setting the session setting alone only takes effect on the next launch.
+		/// </summary>
+		internal void ActivateSelectedList()
+		{
+			if (SelectedListName is not { } selected)
+				return;
+			AppEnv.AppComposition.Current.GetExport<AssemblyTree.AssemblyTreeModel>().ActiveListName = selected;
+		}
+
 		/// <summary>
 		/// The list of preconfigured assembly lists offered by the "Add preconfigured list..."
 		/// menu: the three GAC-based framework lists (only when a GAC is actually present, i.e.