PowerToys/src/modules/fancyzones/editor/FancyZonesEditor/WindowLayout.xaml

<Window x:Class="FancyZonesEditor.WindowLayout"
        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:FancyZonesEditor"
        mc:Ignorable="d"
        Title="Window1" Height="450" Width="800"
        WindowState="Maximized"
        ShowInTaskbar="False"
        ResizeMode="NoResize"
        WindowStyle="None"
        AllowsTransparency="True"
        Background="Transparent"
        Loaded="onLoad"
        >


    <Grid x:Name="Body">
        <Rectangle Fill="White" Opacity="0.5"/>
        
        <Grid x:Name="Window1" >
            <Border BorderThickness="2" BorderBrush="Black">
                <Grid>
<!--                    
                    <Thumb Background="Red" Height="36" VerticalAlignment="Top"/>
                    <Button Height="36" Width="36" VerticalAlignment="Top" Background="Red" FontFamily="Segoe UI Symbol" FontSize="16" Content="✖" HorizontalAlignment="Right"/>
-->
                    <Rectangle Fill="Black" Opacity="0.2"/>
<!--                    
                    <Grid Width="24" Height="24" HorizontalAlignment="Right" VerticalAlignment="Top" Margin="0,10,0,0">
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="*"/>
                        </Grid.ColumnDefinitions>
                        <Rectangle Fill="White" Height="24" Width="2" Margin="-33,0,0,0">
                            <Rectangle.RenderTransform>
                                <RotateTransform Angle="-45"/>
                            </Rectangle.RenderTransform>
                        </Rectangle>
                        <Rectangle Fill="White" Height="24" Width="2" Margin="0,-3,0,0" VerticalAlignment="Center" HorizontalAlignment="Center">
                            <Rectangle.RenderTransform>
                                <RotateTransform Angle="45"/>
                            </Rectangle.RenderTransform>
                        </Rectangle>
                    </Grid> 
-->                    
                </Grid>
            </Border>
        </Grid>
        
    </Grid>
</Window>