Fix #3643 - Mark ClickEvent of PopupBoxContent as handled

src/MaterialDesignThemes.Wpf/SplitButton.cs

@@ -17,7 +17,7 @@ static SplitButton()
 
     public PopupBoxPlacementMode PopupPlacementMode
     {
-        get => (PopupBoxPlacementMode) GetValue(PopupPlacementModeProperty);
+        get => (PopupBoxPlacementMode)GetValue(PopupPlacementModeProperty);
         set => SetValue(PopupPlacementModeProperty, value);
     }
 
@@ -116,7 +116,7 @@ public DataTemplateSelector SplitContentTemplateSelector
 
     public Style ButtonStyle
     {
-        get => (Style) GetValue(ButtonStyleProperty);
+        get => (Style)GetValue(ButtonStyleProperty);
         set => SetValue(ButtonStyleProperty, value);
     }
 
@@ -136,6 +136,17 @@ public override void OnApplyTemplate()
             WeakEventManager<Button, RoutedEventArgs>.AddHandler(_rightButton, nameof(Click), OpenPopupBox);
         }
 
+        if (_popupBox is not null)
+        {
+            _popupBox.RemoveHandler(ButtonBase.ClickEvent, (RoutedEventHandler)PopupContentClickedHandler);
+            _popupBox.AddHandler(ButtonBase.ClickEvent, (RoutedEventHandler)PopupContentClickedHandler);
+        }
+
+        void PopupContentClickedHandler(object sender, RoutedEventArgs e)
+        {
+            e.Handled = true;
+        }
+
         void OpenPopupBox(object? sender, RoutedEventArgs e)
         {
             if (_popupBox is not null)

tests/MaterialDesignThemes.UITests/WPF/SplitButtons/SplitButtonTests.cs

@@ -1,6 +1,6 @@
 using MaterialDesignThemes.UITests.Samples.SplitButton;
 
-[assembly:GenerateHelpers(typeof(SplitButtonWithCommandBinding))]
+[assembly: GenerateHelpers(typeof(SplitButtonWithCommandBinding))]
 
 namespace MaterialDesignThemes.UITests.WPF.SplitButtons;
 
@@ -152,4 +152,41 @@ public async Task SplitButton_CommandCanExecuteFalse_DisablesButton()
 
         recorder.Success();
     }
+
+    [Fact]
+    public async Task SplitButton_ClickingPopupContent_DoesNotExecuteSplitButtonClick()
+    {
+        await using var recorder = new TestRecorder(App);
+
+        //Arrange
+        IVisualElement<SplitButton> splitButton = await LoadXaml<SplitButton>("""
+            <materialDesign:SplitButton VerticalAlignment="Bottom"
+                                        Content="Split Button"
+                                        Style="{StaticResource MaterialDesignRaisedLightSplitButton}">
+              <materialDesign:SplitButton.PopupContent>
+                <Button x:Name="PopupContent" />
+              </materialDesign:SplitButton.PopupContent>
+            </materialDesign:SplitButton>
+            """);
+
+        IVisualElement<PopupBox> popupBox = await splitButton.GetElement<PopupBox>();
+        IVisualElement<Button> popupContent = await splitButton.GetElement<Button>("PopupContent");
+
+        IEventRegistration splitButtonClickEvent = await splitButton.RegisterForEvent(ButtonBase.ClickEvent.Name);
+        IEventRegistration popupContentClickEvent = await popupContent.RegisterForEvent(ButtonBase.ClickEvent.Name);
+
+        //Act
+        await popupBox.LeftClick();
+        //NB: give the popup some time to show
+        await Wait.For(async () => await popupContent.GetIsVisible());
+        await Wait.For(async () => await popupContent.GetActualHeight() > 10);
+        await popupContent.LeftClick();
+        await Task.Delay(50);
+
+        // Assert
+        Assert.Empty(await splitButtonClickEvent.GetInvocations());
+        Assert.Single(await popupContentClickEvent.GetInvocations());
+
+        recorder.Success();
+    }
 }