Fix #3333: Clicking does not select in Assemblies pane when it doesn't have focus

ILSpy/AssemblyTree/AssemblyListPane.xaml.cs

@@ -23,6 +23,7 @@ using System.Windows.Threading;
 using ICSharpCode.ILSpy.ViewModels;
 using ICSharpCode.ILSpyX.TreeView;
 
+using TomsToolbox.Wpf;
 using TomsToolbox.Wpf.Composition.AttributedModel;
 
 namespace ICSharpCode.ILSpy.AssemblyTree
@@ -56,7 +57,7 @@ namespace ICSharpCode.ILSpy.AssemblyTree
 				var selected = model.SelectedItem;
 				if (selected != null)
 				{
-					this.Dispatcher.BeginInvoke(DispatcherPriority.Background, () => {
+					this.BeginInvoke(DispatcherPriority.Background, () => {
 						ScrollIntoView(selected);
 						this.SelectedItem = selected;
 					});
@@ -69,7 +70,8 @@ namespace ICSharpCode.ILSpy.AssemblyTree
 
 				if (SelectedItem is SharpTreeNode selectedItem)
 				{
-					FocusNode(selectedItem);
+					// defer focusing, so it does not interfere with selection via mouse click
+					this.BeginInvoke(() => FocusNode(selectedItem));
 				}
 				else
 				{

ILSpy/AssemblyTree/AssemblyTreeModel.cs

@@ -640,6 +640,7 @@ namespace ICSharpCode.ILSpy.AssemblyTree
 		private void JumpToReference(object? sender, NavigateToReferenceEventArgs e)
 		{
 			JumpToReferenceAsync(e.Reference, e.InNewTabPage).HandleExceptions();
+			IsActive = true;
 		}
 
 		/// <summary>

ILSpy/Controls/TreeView/SharpTreeView.cs

@@ -30,6 +30,8 @@ using System.Windows.Threading;
 
 using ICSharpCode.ILSpyX.TreeView;
 
+using TomsToolbox.Wpf;
+
 namespace ICSharpCode.ILSpy.Controls.TreeView
 {
 	public class SharpTreeView : ListView
@@ -396,9 +398,10 @@ namespace ICSharpCode.ILSpy.Controls.TreeView
 		/// </summary>
 		public void FocusNode(SharpTreeNode node)
 		{
-			if (node == null)
+			ArgumentNullException.ThrowIfNull(node);
-				throw new ArgumentNullException("node");
+
 			ScrollIntoView(node);
+
 			// WPF's ScrollIntoView() uses the same if/dispatcher construct, so we call OnFocusItem() after the item was brought into view.
 			if (this.ItemContainerGenerator.Status == GeneratorStatus.ContainersGenerated)
 			{
@@ -406,7 +409,7 @@ namespace ICSharpCode.ILSpy.Controls.TreeView
 			}
 			else
 			{
-				this.Dispatcher.BeginInvoke(DispatcherPriority.Loaded, new DispatcherOperationCallback(this.OnFocusItem), node);
+				this.BeginInvoke(DispatcherPriority.Loaded, () => OnFocusItem(node));
 			}
 		}