private void treeViewDragDrop(DragEventArgs e)
{
var p = clientPointFrom(e);
var targetNode = _treeView.CalcHitInfo(p).Node;
var draggedNodes = getDraggedNodesFrom(e);
draggedNodes.Each(node => _presenter.MoveNode(node, nodeFrom(targetNode)));
e.Effect = DragDropEffects.None;
}