internal void AddFolder_Click(object sender, RoutedEventArgs e)
 {
     if (_fbd == null)
     {
         _fbd = new FolderBrowserDialog();
     }
     if (_fbd.ShowDialog() != System.Windows.Forms.DialogResult.OK)
     {
         return;
     }
     FileSystemUtils.AddFolderQuery(_fbd.SelectedPath);
 }