Wpf - Drop shadow disappears - wpf

Question

I created a window with no style and added a custom border. I need my window to drop a shadow.
<Border BorderBrush="#000000 "
BorderThickness="1,0,1,1" Width="400"
Height="400"
VerticalAlignment="Stretch" HorizontalAlignment="Stretch"
CornerRadius="10, 10, 0, 0"
Background="Black">
<Border.Effect>
<DropShadowEffect Color="Black" Direction="320"
ShadowDepth="5" Opacity="1" BlurRadius="5" />
</Border.Effect></Border>
But my shadow disappears when I set the width and height like this :
Width="{Binding RelativeSource={RelativeSource FindAncestor,
AncestorType={x:Type Window}}, Path=Width}"
Help me find a solution please. Thanks

Answer 1

Since we don't have the full scope of your solution, I must assume that the Border is within a ControlTemplate that is assigned to the Style of the Window. Remember that if you are going to apply a DropShadowEffect to the root window you need to pad it otherwise you won't see it. Apply Padding="10" to Border and you should see it.

Answer 2

Try To add on the X & Y Thickness of the Shadow to your Windows dimensions

Answer 3

Don't apply effects on the root visuals! In this case, they apply to all children down visual tree and will be cause of reducing performance.
Use the next pattern:
<Grid x:Name="RootWindowGrid">
<Border x:Name="BorderWithEffect" Margin="5">
<Border.Effect>
<DropShadowEffect Color="Black" Direction="320" ShadowDepth="5" Opacity="1" BlurRadius="5" />
</Border.Effect>
</Border>
<Border x:Name="RootBorder_ForAll_Another_Window_Visuals" Margin="5"/>
</Grid>
Margin depends on effect intensivity.