public partial class App : Application
    {
        private static DispatcherOperationCallback exitFrameCallback = new DispatcherOperationCallback(ExitFrame);
        public static void DoEvents()
        {
            DispatcherFrame nestedFrame = new DispatcherFrame();
            DispatcherOperation exitOperation =  Dispatcher.CurrentDispatcher.BeginInvoke (DispatcherPriority.Background, exitFrameCallback, nestedFrame);
            Dispatcher.PushFrame(nestedFrame);
            if (exitOperation.Status !=
            DispatcherOperationStatus.Completed)
            {
                exitOperation.Abort();
            }
        }

        private static Object ExitFrame (Object state)
        {
            DispatcherFrame frame = state as
            DispatcherFrame;
            frame.Continue = false;
            return null;
        }

    }

}