问WPF中的自定义模式窗口？

EN

    private void ShowModalHost(FrameworkElement element)
    {
        //Create new modal host
        var host = new ModalHost(element);

        //Lock out UI with blur
        WindowSurface.Effect = new BlurEffect();
        ModalSurface.IsHitTestVisible = true;

        //Display control in modal surface
        ModalSurface.Children.Add(host);

        //Block until ModalHost is done
        while (ModalSurface.IsHitTestVisible)
        {
            DoEvents();
        }
    }

    private void DoEvents()
    {
        var frame = new DispatcherFrame();
        Dispatcher.BeginInvoke(DispatcherPriority.Background,
            new DispatcherOperationCallback(ExitFrame), frame);
        Dispatcher.PushFrame(frame);            
    }

    private object ExitFrame(object f)
    {
        ((DispatcherFrame)f).Continue = false;

        return null;
    }

    public void CloseModal()
    {
        //Remove any controls from the modal surface and make UI available again
        ModalSurface.Children.Clear();
        ModalSurface.IsHitTestVisible = false;
        WindowSurface.Effect = null;
    }