private void OnModelDeactivated(object sender, DeactivationEventArgs e)
        {
            if (!e.WasClosed)
                return;

            ((IDeactivate)_model).Deactivated -= OnModelDeactivated;

            if (_deactivatingFromView)
                return;

            _deactivateFromViewModel = true;
            _actuallyClosing = true;
            _view.Close();
            _actuallyClosing = false;
            _deactivateFromViewModel = false;
        }