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

<Window x:Class="FancyZonesEditor.LayoutOverlayWindow"
        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="FancyZones Layout" Height="450" Width="800"
        ShowInTaskbar="False"
        ResizeMode="NoResize"
        WindowStyle="None"
        AllowsTransparency="True"
        Background="Transparent"/>