private void Window_Closed(object sender, EventArgs e)
 {
     if (WindowResult == WindowDialogResult.Invalid)
     {
         WindowResult = WindowDialogResult.Cancel;
     }
 }
 private void Cancel_Click(object sender, RoutedEventArgs e)
 {
     WindowResult = WindowDialogResult.Cancel;
     Close();
 }
 private void NoSave_Click(object sender, RoutedEventArgs e)
 {
     WindowResult = WindowDialogResult.No;
     Close();
 }