PowerToys/src/core/Microsoft.PowerToys.Settings.UI.Island/MainWindow.xaml

<Window x:Class="SettingsMain.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:SettingsMain"
        xmlns:Controls="clr-namespace:Microsoft.Toolkit.Wpf.UI.Controls;assembly=Microsoft.Toolkit.Wpf.UI.Controls"
        mc:Ignorable="d"
        Title="PowerToys Settings" Height="800" Width="800">

    <Grid>

    </Grid>

</Window>