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

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

    <Grid>
        <!--<xaml:WindowsXamlHost InitialTypeName="Microsoft.PowerToys.Settings.UI.Controls.DummyUserControl" ChildChanged="WindowsXamlHost_ChildChanged" />-->
        <xaml:WindowsXamlHost InitialTypeName="Microsoft.PowerToys.Settings.UI.Views.ShellPage" ChildChanged="WindowsXamlHost_ChildChanged" />
    </Grid>

</Window>