Adding shadow to WPF form with BorderThickness = 0

Question

I have a WPF borderless window with a shadow set to the grid shown below:

<Window x:Class="Wpf.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525" WindowStyle="None" 
        AllowsTransparency="True" Background="Transparent" BorderThickness="0">
    <Grid>
        <Grid.Effect>
            <DropShadowEffect BlurRadius="15" Direction="-90" RenderingBias="Quality" ShadowDepth="2"/>
        </Grid.Effect>
    </Grid>
</Window>

However, when the BorderThickness is set to 0, the shadow doesn't appear. When I increase this, the shadow will appear, but when the window is moved to the edge of the screen using DragMove(), a gap is left (presumably the width of BorderThickness).

How can I, therefore, add a shadow around the window with BorderThickness set to 0? Thanks in advance.

Answer 1

 <Window x:Class="WpfApp7.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:WpfApp7"
    mc:Ignorable="d" WindowStyle="None" 
    AllowsTransparency="True" Background="Transparent" BorderThickness="0"
    Title="MainWindow" Height="450" Width="800">
<Grid Margin="10">
    <Grid.Background>
        <SolidColorBrush Color="Green" Opacity="1"/>
    </Grid.Background>
      <Grid.Effect>
        <DropShadowEffect Color="Black"  BlurRadius="15" Direction="-90" 
                  RenderingBias="Quality" ShadowDepth="2"/>
      </Grid.Effect>
    </Grid>

:) just add margin to the grid. It needs space to show the shadow.