我迷失了這個，我希望我的 Viewmodel 使用事件委托，以便我可以訂閱它，打開一些對話框并等待對話框結果。稍后 ViewModel 應該對對話結果做任何它想做的事情。這是我實現它的方式（恢復代碼）：public class MyViewModel(){   public delegate TributaryDocument SearchDocumentEventHandler();   public event SearchDocumentEventHandler SearchDocument;   //Command for the search button   public CommandRelay SearchDocumentCommand { get; set; }   //Document that i found in the dialog.   public TributaryDocument Document { get; set; }   public MyViewModel()   {      SearchDocumentCommand = new CommandRelay(DoSearchDocument);   }   //The command execution   public void DoSearchDocument()   {       //Event used here !       Document = SearchDocument?.Invoke();   }}public class MyUIControl : UserControl{    public MainWindow MainWindow { get; }    public MyUIControl()    {       MainWindow = Application.Current.Windows[0] as MainWindow;       DataContextChanged += MyUIControl_DataContextChanged;    }    private void MyUIControl_DataContextChanged(object sender, DependencyPropertyChangedEventArgs e)    {        var modelView = (MyViewModel)DataContext;        modelView.SearchDocument += MyUIControl_SearchDocument;    }    private TributaryDocument MyUIControl_SearchDocument()    {       //Dont know what to do here... i am lost on this part.       return await MainWindow.ShowDialog(new MyDocumentSearcherDialog());    }}//The signature for MainWindow.ShowDialogpublic async Task<object> ShowDialog(object dialog){   return await DialogHost.Show(dialog, "MainDialog");}