public virtual void TreeMouseDown(MouseEventArgs e)
        {
            _hitInfo = null;
            var hitInfo = _treeView.CalcHitInfo(new Point(e.X, e.Y));

            if (hitInfo == null)
            {
                return;
            }
            if (hitInfo.Node == null)
            {
                return;
            }
            if (!_presenter.CanDrag(nodeFrom(hitInfo.Node)))
            {
                return;
            }
            _hitInfo = hitInfo;
        }