private void OnRequestClose(object sender, DialogCloseEventArgs e)
 {
     try
     {
         DialogResult = e.Result;
     }
     catch (InvalidOperationException)
     {
         Close();
     }
 }
 protected void OnRequestClose(DialogCloseEventArgs e)
 {
     EventHandler<DialogCloseEventArgs> handler = RequestClose;
     if (handler != null) handler(this, e);
 }