private void MoveDownOnClick(object sender, RoutedEventArgs e)
{
var oldIndex = this.ViewModel.Windows.IndexOf(this.ViewModel.SelectedWindow);
this.ViewModel.Windows.Insert(oldIndex + 2, this.ViewModel.SelectedWindow);
this.ViewModel.Windows.RemoveAt(oldIndex);
this.ViewModel.SelectedWindow = this.ViewModel.Windows[oldIndex + 1];
}