void TreeView_DragEnter (object sender, DragEventArgs e)
{
// Retrieve the client coordinates of the mouse position
Point targetPoint = _treeView.PointToClient (new Point (e.X, e.Y));
// Retrieve the node at the mouse position
TreeNode targetNode = _treeView.GetNodeAt (targetPoint);
_eventsText.AppendText ("DragEnter: " + targetNode.Text
+ Environment.NewLine);
e.Effect = e.AllowedEffect;
}