using System;
using System.Drawing;
using System.Windows.Forms;

public class Form4 : Form
 private TreeView treeView1;

 public Form4()
  treeView1 = new TreeView();


  // Initialize treeView1.
  treeView1.AllowDrop = true;
  treeView1.Dock = DockStyle.Fill;

  // Add nodes to treeView1.
  TreeNode node;
  for (int x = 0; x < 3; ++x)
   // Add a root node to treeView1.
   node = treeView1.Nodes.Add(String.Format("Node{0}", x*4));
   for (int y = 1; y < 4; ++y)
    // Add a child node to the previously added node.
    node = node.Nodes.Add(String.Format("Node{0}", x*4 + y));

  // Add event handlers for the required drag events.
  treeView1.ItemDrag += new ItemDragEventHandler(treeView1_ItemDrag);
  treeView1.DragEnter += new DragEventHandler(treeView1_DragEnter);
  treeView1.DragOver += new DragEventHandler(treeView1_DragOver);
  treeView1.DragDrop += new DragEventHandler(treeView1_DragDrop);

  // Initialize the form.
  this.ClientSize = new Size(292, 273);


// static void Main()
// {
//  Application.Run(new Form1());
// }
 private void treeView1_ItemDrag(object sender, ItemDragEventArgs e)
  // Move the dragged node when the left mouse button is used.
  if (e.Button == MouseButtons.Left)
   DoDragDrop(e.Item, DragDropEffects.Move);

   // Copy the dragged node when the right mouse button is used.
  else if (e.Button == MouseButtons.Right)
   DoDragDrop(e.Item, DragDropEffects.Copy);

 // Set the target drop effect to the effect
 // specified in the ItemDrag event handler.
 private void treeView1_DragEnter(object sender, DragEventArgs e)
  e.Effect = e.AllowedEffect;

 // Select the node under the mouse pointer to indicate the
 // expected drop location.
 private void treeView1_DragOver(object sender, DragEventArgs e)
  // Retrieve the client coordinates of the mouse position.
  Point targetPoint = treeView1.PointToClient(new Point(e.X, e.Y));

  // Select the node at the mouse position.
  treeView1.SelectedNode = treeView1.GetNodeAt(targetPoint);

 private void treeView1_DragDrop(object sender, DragEventArgs e)
  // Retrieve the client coordinates of the drop location.
  Point targetPoint = treeView1.PointToClient(new Point(e.X, e.Y));

  // Retrieve the node at the drop location.
  TreeNode targetNode = treeView1.GetNodeAt(targetPoint);

  // Retrieve the node that was dragged.
  TreeNode draggedNode = (TreeNode)e.Data.GetData(typeof(TreeNode));

  // Confirm that the node at the drop location is not
  // the dragged node or a descendant of the dragged node.
  if (!draggedNode.Equals(targetNode) && !ContainsNode(draggedNode, targetNode))
   // If it is a move operation, remove the node from its current
   // location and add it to the node at the drop location.
   if (e.Effect == DragDropEffects.Move)

    // If it is a copy operation, clone the dragged node
    // and add it to the node at the drop location.
   else if (e.Effect == DragDropEffects.Copy)

   // Expand the node at the location
   // to show the dropped node.

 // Determine whether one node is a parent
 // or ancestor of a second node.
 private bool ContainsNode(TreeNode node1, TreeNode node2)
  // Check the parent node of the second node.
  if (node2.Parent == null) return false;
  if (node2.Parent.Equals(node1)) return true;

  // If the parent node is not null or equal to the first node,
  // call the ContainsNode method recursively using the parent of
  // the second node.
  return ContainsNode(node1, node2.Parent);



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