Forward ScrollViewerAssist.BubbleVerticalScroll to nested ScrollViewers (#4057)

corvinsz · Keboo · web-flow · commit 5ee1c9d6c3e5 · 2026-05-29T05:00:13.000Z
* docs: add reproduction to demo app * fix: forward ScrollViewerAssist.BubbleVerticalScroll to nested ScrollViewers * fix: properly unregister ScrollViewerAssist event handlers Ensure `MouseWheel` and `Unloaded` event handlers are detached when `ScrollViewerAssist` functionality is removed from a `ScrollViewer`. This prevents potential memory leaks or incorrect behavior. Resolves #4055 * Revert "docs: add reproduction to demo app" This reverts commit 2aa7e08. --------- Co-authored-by: Kevin Bost <kitokeboo@gmail.com>
diff --git a/src/MaterialDesignThemes.Wpf/ScrollViewerAssist.cs b/src/MaterialDesignThemes.Wpf/ScrollViewerAssist.cs
@@ -56,7 +56,7 @@ public static PaddingMode GetPaddingMode(DependencyObject element)
         => (PaddingMode)element.GetValue(PaddingModeProperty);
 
     public static readonly DependencyProperty IgnorePaddingProperty = DependencyProperty.RegisterAttached(
-    "IgnorePadding", typeof(bool), typeof(ScrollViewerAssist), new PropertyMetadata(true));
+        "IgnorePadding", typeof(bool), typeof(ScrollViewerAssist), new PropertyMetadata(true));
 
     public static void SetIgnorePadding(DependencyObject element, bool value) => element.SetValue(IgnorePaddingProperty, value);
     public static bool GetIgnorePadding(DependencyObject element) => (bool)element.GetValue(IgnorePaddingProperty);
@@ -191,7 +191,7 @@ private static void OnBubbleVerticalScrollChanged(DependencyObject d, Dependency
         {
             if (sv.IsLoaded)
             {
-                DoOnLoaded(sv);
+                ApplyBubbleVerticalScrollHooks(sv);
             }
             else
             {
@@ -204,7 +204,7 @@ static void OnLoaded(object? sender, RoutedEventArgs e)
         {
             if (sender is ScrollViewer sv)
             {
-                DoOnLoaded(sv);
+                ApplyBubbleVerticalScrollHooks(sv);
             }
         }
 
@@ -244,7 +244,7 @@ static void RegisterForMouseWheelEvent(ScrollViewer sv)
             sv.AddHandler(UIElement.MouseWheelEvent, (RoutedEventHandler)ScrollViewerOnMouseWheel, true);
         }
 
-        static void DoOnLoaded(ScrollViewer sv)
+        static void ApplyBubbleVerticalScrollHooks(ScrollViewer sv)
         {
             if (GetBubbleVerticalScroll(sv))
             {
@@ -255,6 +255,8 @@ static void DoOnLoaded(ScrollViewer sv)
             else
             {
                 RemoveHook(sv);
+                UnregisterForMouseWheelEvent(sv);
+                UnregisterForUnloadedEvent(sv);
             }
         }
 
diff --git a/src/MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.DataGrid.xaml b/src/MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.DataGrid.xaml
@@ -489,7 +489,7 @@
                   BorderThickness="{TemplateBinding BorderThickness}"
                   CornerRadius="{TemplateBinding wpf:DataGridAssist.CornerRadius}"
                   SnapsToDevicePixels="True">
-            <ScrollViewer x:Name="DG_ScrollViewer" Focusable="false">
+            <ScrollViewer x:Name="DG_ScrollViewer" Focusable="false" wpf:ScrollViewerAssist.BubbleVerticalScroll="{Binding Path=(wpf:ScrollViewerAssist.BubbleVerticalScroll), RelativeSource={RelativeSource TemplatedParent}}">
               <ScrollViewer.Template>
                 <ControlTemplate TargetType="{x:Type ScrollViewer}">
                   <Grid>
diff --git a/src/MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.ListBox.xaml b/src/MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.ListBox.xaml
@@ -358,6 +358,7 @@
             <ScrollViewer Padding="{TemplateBinding Padding}"
                           wpf:ScrollViewerAssist.IgnorePadding="{Binding Path=(wpf:ScrollViewerAssist.IgnorePadding), RelativeSource={RelativeSource TemplatedParent}}"
                           wpf:ScrollViewerAssist.PaddingMode="{Binding Path=(wpf:ScrollViewerAssist.PaddingMode), RelativeSource={RelativeSource TemplatedParent}}"
+                          wpf:ScrollViewerAssist.BubbleVerticalScroll="{Binding Path=(wpf:ScrollViewerAssist.BubbleVerticalScroll), RelativeSource={RelativeSource TemplatedParent}}"
                           ClipToBounds="False"
                           Focusable="false">
               <ItemsPresenter ClipToBounds="False" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
@@ -641,7 +642,8 @@
             <ScrollViewer Padding="{TemplateBinding Padding}"
                           Focusable="false"
                           wpf:ScrollViewerAssist.IgnorePadding="{Binding Path=(wpf:ScrollViewerAssist.IgnorePadding), RelativeSource={RelativeSource TemplatedParent}}"
-                          wpf:ScrollViewerAssist.PaddingMode="{Binding Path=(wpf:ScrollViewerAssist.PaddingMode), RelativeSource={RelativeSource TemplatedParent}}">
+                          wpf:ScrollViewerAssist.PaddingMode="{Binding Path=(wpf:ScrollViewerAssist.PaddingMode), RelativeSource={RelativeSource TemplatedParent}}"
+                          wpf:ScrollViewerAssist.BubbleVerticalScroll="{Binding Path=(wpf:ScrollViewerAssist.BubbleVerticalScroll), RelativeSource={RelativeSource TemplatedParent}}">
               <ItemsPresenter SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
             </ScrollViewer>
           </Border>
diff --git a/src/MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.ListView.xaml b/src/MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.ListView.xaml
@@ -34,6 +34,7 @@
                             wpf:ScrollViewerAssist.SyncHorizontalOffset="{Binding HorizontalOffset, Mode=OneWay, RelativeSource={RelativeSource TemplatedParent}}"
                             wpf:ScrollViewerAssist.IgnorePadding="{Binding Path=(wpf:ScrollViewerAssist.IgnorePadding), RelativeSource={RelativeSource TemplatedParent}}"
                             wpf:ScrollViewerAssist.PaddingMode="{Binding Path=(wpf:ScrollViewerAssist.PaddingMode), RelativeSource={RelativeSource TemplatedParent}}"
+                            wpf:ScrollViewerAssist.BubbleVerticalScroll="{Binding Path=(wpf:ScrollViewerAssist.BubbleVerticalScroll), RelativeSource={RelativeSource TemplatedParent}}"
                             DockPanel.Dock="Top"
                             Focusable="false"
                             HorizontalScrollBarVisibility="Hidden"
@@ -212,9 +213,9 @@
       <converters:ListViewGridViewConverter x:Key="MaterialDesignListViewTemplateConverter">
         <converters:ListViewGridViewConverter.DefaultValue>
           <ControlTemplate TargetType="{x:Type ListView}">
-            <ScrollViewer>
+            <ScrollViewer wpf:ScrollViewerAssist.BubbleVerticalScroll="{Binding Path=(wpf:ScrollViewerAssist.BubbleVerticalScroll), RelativeSource={RelativeSource TemplatedParent}}">
               <ItemsPresenter />
-            </ScrollViewer>
+            </ScrollViewer> 
             <ControlTemplate.Triggers>
               <Trigger Property="IsGrouping" Value="True">
                 <Setter Property="ScrollViewer.CanContentScroll" Value="false" />
@@ -224,7 +225,8 @@
         </converters:ListViewGridViewConverter.DefaultValue>
         <converters:ListViewGridViewConverter.ViewValue>
           <ControlTemplate TargetType="{x:Type ListView}">
-            <ScrollViewer Style="{DynamicResource {x:Static GridView.GridViewScrollViewerStyleKey}}">
+            <ScrollViewer Style="{DynamicResource {x:Static GridView.GridViewScrollViewerStyleKey}}"
+                          wpf:ScrollViewerAssist.BubbleVerticalScroll="{Binding Path=(wpf:ScrollViewerAssist.BubbleVerticalScroll), RelativeSource={RelativeSource TemplatedParent}}">
               <ItemsPresenter />
             </ScrollViewer>
             <ControlTemplate.Triggers>
diff --git a/src/MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.TreeListView.xaml b/src/MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.TreeListView.xaml
@@ -284,6 +284,7 @@
                           Style="{DynamicResource {x:Static GridView.GridViewScrollViewerStyleKey}}"
                           wpf:ScrollViewerAssist.IgnorePadding="{Binding Path=(wpf:ScrollViewerAssist.IgnorePadding), RelativeSource={RelativeSource TemplatedParent}}"
                           wpf:ScrollViewerAssist.PaddingMode="{Binding Path=(wpf:ScrollViewerAssist.PaddingMode), RelativeSource={RelativeSource TemplatedParent}}"
+                          wpf:ScrollViewerAssist.BubbleVerticalScroll="{Binding Path=(wpf:ScrollViewerAssist.BubbleVerticalScroll), RelativeSource={RelativeSource TemplatedParent}}"
                           Padding="{TemplateBinding Padding}"
                           Background="{TemplateBinding Background}"
                           CanContentScroll="false"
diff --git a/src/MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.TreeView.xaml b/src/MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.TreeView.xaml
@@ -23,6 +23,7 @@
                           Background="{TemplateBinding Background}"
                           wpf:ScrollViewerAssist.IgnorePadding="{Binding Path=(wpf:ScrollViewerAssist.IgnorePadding), RelativeSource={RelativeSource TemplatedParent}}"
                           wpf:ScrollViewerAssist.PaddingMode="{Binding Path=(wpf:ScrollViewerAssist.PaddingMode), RelativeSource={RelativeSource TemplatedParent}}"
+                          wpf:ScrollViewerAssist.BubbleVerticalScroll="{Binding Path=(wpf:ScrollViewerAssist.BubbleVerticalScroll), RelativeSource={RelativeSource TemplatedParent}}"
                           CanContentScroll="false"
                           Focusable="false"
                           HorizontalScrollBarVisibility="{TemplateBinding ScrollViewer.HorizontalScrollBarVisibility}"

Original file line number	Diff line number	Diff line change
`@@ -56,7 +56,7 @@ public static PaddingMode GetPaddingMode(DependencyObject element)`
`56`	`56`	`=> (PaddingMode)element.GetValue(PaddingModeProperty);`
`57`	`57`
`58`	`58`	`public static readonly DependencyProperty IgnorePaddingProperty = DependencyProperty.RegisterAttached(`
`59`		`- "IgnorePadding", typeof(bool), typeof(ScrollViewerAssist), new PropertyMetadata(true));`
	`59`	`+ "IgnorePadding", typeof(bool), typeof(ScrollViewerAssist), new PropertyMetadata(true));`
`60`	`60`
`61`	`61`	`public static void SetIgnorePadding(DependencyObject element, bool value) => element.SetValue(IgnorePaddingProperty, value);`
`62`	`62`	`public static bool GetIgnorePadding(DependencyObject element) => (bool)element.GetValue(IgnorePaddingProperty);`
`@@ -191,7 +191,7 @@ private static void OnBubbleVerticalScrollChanged(DependencyObject d, Dependency`
`191`	`191`	`{`
`192`	`192`	`if (sv.IsLoaded)`
`193`	`193`	`{`
`194`		`- DoOnLoaded(sv);`
	`194`	`+ ApplyBubbleVerticalScrollHooks(sv);`
`195`	`195`	`}`
`196`	`196`	`else`
`197`	`197`	`{`
`@@ -204,7 +204,7 @@ static void OnLoaded(object? sender, RoutedEventArgs e)`
`204`	`204`	`{`
`205`	`205`	`if (sender is ScrollViewer sv)`
`206`	`206`	`{`
`207`		`- DoOnLoaded(sv);`
	`207`	`+ ApplyBubbleVerticalScrollHooks(sv);`
`208`	`208`	`}`
`209`	`209`	`}`
`210`	`210`
`@@ -244,7 +244,7 @@ static void RegisterForMouseWheelEvent(ScrollViewer sv)`
`244`	`244`	`sv.AddHandler(UIElement.MouseWheelEvent, (RoutedEventHandler)ScrollViewerOnMouseWheel, true);`
`245`	`245`	`}`
`246`	`246`
`247`		`- static void DoOnLoaded(ScrollViewer sv)`
	`247`	`+ static void ApplyBubbleVerticalScrollHooks(ScrollViewer sv)`
`248`	`248`	`{`
`249`	`249`	`if (GetBubbleVerticalScroll(sv))`
`250`	`250`	`{`
`@@ -255,6 +255,8 @@ static void DoOnLoaded(ScrollViewer sv)`
`255`	`255`	`else`
`256`	`256`	`{`
`257`	`257`	`RemoveHook(sv);`
	`258`	`+ UnregisterForMouseWheelEvent(sv);`
	`259`	`+ UnregisterForUnloadedEvent(sv);`
`258`	`260`	`}`
`259`	`261`	`}`
`260`	`262`