void TreeView_ItemDrag (object sender, ItemDragEventArgs e)
{
TreeNode draggedNode = (TreeNode) e.Item;
_eventsText.AppendText ("ItemDrag (Begin): " + draggedNode.Text
+ Environment.NewLine);
if (e.Button == MouseButtons.Left)
DoDragDrop (e.Item, DragDropEffects.Move);
else if (e.Button == MouseButtons.Right)
DoDragDrop (e.Item, DragDropEffects.Copy);
_eventsText.AppendText ("ItemDrag (End): " + draggedNode.Text
+ Environment.NewLine);
}