Adds IsInteractiveElement attached property

Introduces an `IsInteractiveElement` attached dependency property to `AutoSuggestBox`, updates `OnLostFocus` to prevent popup closure when the suggestion list is focused, refactors interactivity detection to prioritize the new attached property and perform visual tree traversal, and adds new UI tests to validate this functionality.

Author: Keboo

src/MaterialDesignThemes.Wpf/AutoSuggestBox.cs

@@ -9,6 +9,15 @@ namespace MaterialDesignThemes.Wpf;
 [TemplatePart(Name = AutoSuggestBoxListPart, Type = typeof(ListBox))]
 public class AutoSuggestBox : TextBox
 {
+    public static bool? GetIsInteractiveElement(DependencyObject obj)
+        => (bool?)obj.GetValue(IsInteractiveElementProperty);
+
+    public static void SetIsInteractiveElement(DependencyObject obj, bool? value)
+        => obj.SetValue(IsInteractiveElementProperty, value);
+
+    public static readonly DependencyProperty IsInteractiveElementProperty =
+        DependencyProperty.RegisterAttached("IsInteractiveElement", typeof(bool?), typeof(AutoSuggestBox), new PropertyMetadata(null));
+
     private const string AutoSuggestBoxListPart = "PART_AutoSuggestBoxList";
 
     protected ListBox? _autoSuggestBoxList;
@@ -186,6 +195,11 @@ protected override void OnPreviewKeyDown(KeyEventArgs e)
     protected override void OnLostFocus(RoutedEventArgs e)
     {
         base.OnLostFocus(e);
+        if (_autoSuggestBoxList is { } list &&
+            (list.IsKeyboardFocused || list.IsKeyboardFocusWithin))
+        {
+            return;
+        }
         CloseAutoSuggestionPopUp();
     }
     protected override void OnTextChanged(TextChangedEventArgs e)
@@ -209,8 +223,10 @@ private void AutoSuggestionListBox_PreviewMouseDown(object sender, MouseButtonEv
             return;
 
         // If the user clicked on an interactive element, let it handle the event.
-        if (IsInteractiveElement(e.OriginalSource as DependencyObject))
+        if (IsInteractiveElement(element))
+        {
             return;
+        }
 
         var selectedItem = element.DataContext;
         if (!_autoSuggestBoxList.Items.Contains(selectedItem))
@@ -241,18 +257,28 @@ void OnSelectionChanged(object s, SelectionChangedEventArgs args)
     #endregion
 
     #region Methods
-    private static bool IsInteractiveElement(DependencyObject? element)
+    private bool IsInteractiveElement(DependencyObject? element)
     {
-        while (element is not null)
+        return element.GetVisualAncestry()
+            .Where(x => x != this)
+            .Select(IsInteractive)
+            .Where(x => x is not null)
+            .FirstOrDefault() ?? false;
+
+        static bool? IsInteractive(DependencyObject element)
         {
+            if (GetIsInteractiveElement(element) is bool isInteractiveElement)
+            {
+                return isInteractiveElement;
+            }
             if (element is ButtonBase or TextBoxBase or ComboBox or Hyperlink)
             {
                 return true;
             }
-            element = VisualTreeHelper.GetParent(element);
+            return null;
         }
-        return false;
     }
+
     private void CloseAutoSuggestionPopUp()
     {
         IsSuggestionOpen = false;

tests/MaterialDesignThemes.UITests/Samples/AutoSuggestBoxes/AutoSuggestTextBoxWithInteractiveTemplate.xaml

@@ -20,7 +20,9 @@
             <ColumnDefinition Width="auto" />
           </Grid.ColumnDefinitions>
           <StackPanel Grid.Column="0" Orientation="Horizontal">
-            <TextBlock VerticalAlignment="Center" Text="{Binding Name}" />
+            <TextBlock VerticalAlignment="Center" Text="{Binding Name}"
+                       Background="Transparent"
+                       x:Name="NameTextblock"/>
             <TextBlock Margin="8,0"
                        VerticalAlignment="Center"
                        Text="{Binding Count}" />

tests/MaterialDesignThemes.UITests/Samples/AutoSuggestBoxes/AutoSuggestTextBoxWithInteractiveTemplate.xaml.cs

@@ -1,19 +1,4 @@
-using System;
-using System.Collections.Generic;
-using System.Collections.ObjectModel;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-using System.Windows;
-using System.Windows.Controls;
-using System.Windows.Data;
-using System.Windows.Documents;
-using System.Windows.Input;
-using System.Windows.Media;
-using System.Windows.Media.Imaging;
-using System.Windows.Navigation;
-using System.Windows.Shapes;
-using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
 
 namespace MaterialDesignThemes.UITests.Samples.AutoSuggestBoxes;
@@ -32,7 +17,7 @@ public AutoSuggestTextBoxWithInteractiveTemplate()
 
 public partial class AutoSuggestTextBoxWithInteractiveTemplateViewModel : ObservableObject
 {
-    private List<SuggestionThing2> _baseSuggestions;
+    private readonly List<SuggestionThing2> _baseSuggestions;
 
     [ObservableProperty]
     private List<SuggestionThing2> _suggestions = [];
@@ -63,7 +48,7 @@ public AutoSuggestTextBoxWithInteractiveTemplateViewModel()
             new("Mtn Dew"),
             new("Orange")
         ];
-        Suggestions = new(_baseSuggestions);
+        Suggestions = [.. _baseSuggestions];
     }
 
     private static bool IsMatch(string item, string currentText)

tests/MaterialDesignThemes.UITests/WPF/AutoSuggestBoxes/AutoSuggestTextBoxTests.cs

@@ -8,7 +8,7 @@ public class AutoSuggestBoxTests : TestBase
 {
     public AutoSuggestBoxTests()
     {
-        AttachedDebuggerToRemoteProcess = false;
+        AttachedDebuggerToRemoteProcess = true;
     }
 
     [Test]
@@ -245,16 +245,15 @@ public async Task AutoSuggestBox_ClickingButtonInInteractiveItemTemplate_DoesNot
         // Act
         await suggestBox.MoveKeyboardFocus();
         await suggestBox.SendInput(new KeyboardInput("a"));
-        await Task.Delay(50, TestContext.Current!.CancellationToken);
+        await Task.Delay(500, TestContext.Current!.CancellationToken);
 
         // Find the button in the first suggestion item
         var thirdListBoxItem = await suggestionListBox.GetElement<ListBoxItem>("/ListBoxItem[2]");
         var button = await thirdListBoxItem.GetElement<Button>();
 
         // Click the button
-        await button.MoveCursorTo();
         await button.LeftClick();
-        await Task.Delay(50, TestContext.Current!.CancellationToken);
+        await Task.Delay(500, TestContext.Current!.CancellationToken);
 
         // Assert
         await Assert.That(await suggestBox.GetIsSuggestionOpen()).IsTrue();
@@ -271,6 +270,76 @@ static async Task AssertViewModelProperty(AutoSuggestBox autoSuggestBox)
         recorder.Success();
     }
 
+    [Test]
+    public async Task AutoSuggestBox_ClickingButtonForcingNonInteractive_SelectsItemAndClosesPopup()
+    {
+        await using var recorder = new TestRecorder(App);
+
+        // Arrange
+        IVisualElement<AutoSuggestBox> suggestBox = (await LoadUserControl<AutoSuggestTextBoxWithInteractiveTemplate>()).As<AutoSuggestBox>();
+        IVisualElement<Popup> popup = await suggestBox.GetElement<Popup>();
+        IVisualElement<ListBox> suggestionListBox = await popup.GetElement<ListBox>();
+
+        // Act
+        await suggestBox.MoveKeyboardFocus();
+        await suggestBox.SendInput(new KeyboardInput("a"));
+        await Task.Delay(500, TestContext.Current!.CancellationToken);
+
+        // Find the button in the first suggestion item
+        var thirdListBoxItem = await suggestionListBox.GetElement<ListBoxItem>("/ListBoxItem[2]");
+        var button = await thirdListBoxItem.GetElement<Button>();
+
+        static void SetNonInteractive(Button button)
+            => AutoSuggestBox.SetIsInteractiveElement(button, false);
+        await button.RemoteExecute(SetNonInteractive);
+
+        // Click the button
+        await button.LeftClick();
+        await Task.Delay(500, TestContext.Current!.CancellationToken);
+
+        // Assert
+        await Assert.That(await suggestBox.GetIsSuggestionOpen()).IsFalse();
+
+        recorder.Success();
+    }
+
+    [Test]
+    public async Task AutoSuggestBox_ClickingTextblockThatIsInteractive_DoesNotSelectOrClosePopup()
+    {
+        await using var recorder = new TestRecorder(App);
+
+        // Arrange
+        IVisualElement<AutoSuggestBox> suggestBox = (await LoadUserControl<AutoSuggestTextBoxWithInteractiveTemplate>()).As<AutoSuggestBox>();
+        IVisualElement<Popup> popup = await suggestBox.GetElement<Popup>();
+        IVisualElement<ListBox> suggestionListBox = await popup.GetElement<ListBox>();
+
+        // Act
+        await suggestBox.MoveKeyboardFocus();
+        await suggestBox.SendInput(new KeyboardInput("a"));
+        await Task.Delay(500, TestContext.Current!.CancellationToken);
+
+        // Find the button in the first suggestion item
+        var thirdListBoxItem = await suggestionListBox.GetElement<ListBoxItem>("/ListBoxItem[2]");
+        var textBlock = await thirdListBoxItem.GetElement<TextBlock>("NameTextblock");
+
+        static void SetInteractive(TextBlock textBlock)
+            => AutoSuggestBox.SetIsInteractiveElement(textBlock, true);
+        await textBlock.RemoteExecute(SetInteractive);
+
+        // Click the button
+        await textBlock.LeftClick();
+        await Task.Delay(500, TestContext.Current!.CancellationToken);
+
+        // Assert
+        await Assert.That(await suggestBox.GetIsSuggestionOpen()).IsTrue();
+
+        // The list box item should selected because the TextBlock does not handle the click
+        int selectedIndex = await suggestionListBox.GetSelectedIndex();
+        await Assert.That(selectedIndex).IsEqualTo(2); 
+
+        recorder.Success();
+    }
+
     private static async Task AssertExists(IVisualElement<ListBox> suggestionListBox, string text, bool existsOrNotCheck = true)
     {
         try