Merge pull request #4583 from AvaloniaUI/fixes/window-hit-testing

fix window hit testing.

src/Avalonia.Themes.Default/Window.xaml

@@ -8,6 +8,7 @@
       <Panel>
         <Border Name="PART_TransparencyFallback" IsHitTestVisible="False" />
         <Border Background="{TemplateBinding Background}" IsHitTestVisible="False" />
+        <Panel Background="Transparent" Margin="{TemplateBinding WindowDecorationMargin}" />
         <VisualLayerManager>
           <VisualLayerManager.ChromeOverlayLayer>
             <TitleBar />

src/Avalonia.Themes.Fluent/Window.xaml

@@ -9,6 +9,7 @@
       <Panel>
         <Border Name="PART_TransparencyFallback" IsHitTestVisible="False" />
         <Border Background="{TemplateBinding Background}" IsHitTestVisible="False" />
+        <Panel Background="Transparent" Margin="{TemplateBinding WindowDecorationMargin}" />
         <VisualLayerManager>
           <VisualLayerManager.ChromeOverlayLayer>
             <TitleBar />