Avalonia/samples/ControlCatalog/Pages/WindowPage.xaml

<UserControl xmlns="https://github.com/avaloniaui">
  <StackPanel Orientation="Vertical" Gap="4">
    <Button Content="Open Window" Command="{Binding OpenWindowCommand}" />
    <Button Content="Open Window Modal" Command="{Binding OpenModalWindowCommand}" />
    <Button Content="Open Owned Window" Command="{Binding OpenOwnedWindowCommand}" />
    <Button Content="Open Owned Window Modal" Command="{Binding OpenOwnedModalWindowCommand}" />
  </StackPanel>
</UserControl>