public static extern ulong FlutterDesktopProcessMessages(FlutterDesktopViewControllerRef controller);
public static extern FlutterDesktopPluginRegistrarRef FlutterDesktopGetPluginRegistrar(FlutterDesktopViewControllerRef controller, [MarshalAs(UnmanagedType.LPStr)] string pluginName);
public static extern FlutterDesktopViewRef FlutterDesktopGetView(FlutterDesktopViewControllerRef controller);