Avalonia/samples/ControlCatalog/Pages/DialogsPage.xaml

<UserControl xmlns="https://github.com/avaloniaui">
  <StackPanel Orientation="Vertical" Spacing="4" Margin="4">
      <Button Name="OpenFile">Open File</Button>
      <Button Name="SaveFile">Save File</Button>
      <Button Name="SelectFolder">Select Folder</Button>
      <StackPanel Orientation="Horizontal">
          <CheckBox Name="IsModal" IsChecked="True"/>
          <TextBlock>Modal to window</TextBlock>
      </StackPanel>
      <Button Name="DecoratedWindow">Decorated window</Button>
  </StackPanel>
</UserControl>