c# TreeViewに右クリックイベントを登録する

-TreeView のアイテムを右クリックした場合にポップアップメニューを表示する。

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

class FormMain : Form {

	private TreeView menuTreeView;
	private ContextMenuStrip docMenu;

	[STAThread]
	public static void Main() {
		Application.EnableVisualStyles();
		Application.SetCompatibleTextRenderingDefault(false);
		Application.Run( new FormMain());
	}

	FormMain()
	{
		InitializeMenuTreeView();
	}

	public void contextMenuStrip_SubMenuClick(object sender, EventArgs e)
	{
		string s = ((ToolStripMenuItem)sender).Text;

		MessageBox.Show("Item is " + s, "Item Clicke");
	}
	
	public void InitializeMenuTreeView()
	{
	    // Create the TreeView.
	    menuTreeView = new TreeView();
	    menuTreeView.Size = new Size(200, 200);

	    // Create the root node.
	    TreeNode docNode = new TreeNode("Documents");

	    // Add some additional nodes.
	    docNode.Nodes.Add("phoneList.doc");
	    docNode.Nodes.Add("resume.doc");

	    // Add the root nodes to the TreeView.
	    menuTreeView.Nodes.Add(docNode);

	    // Create the ContextMenuStrip.
	    docMenu = new ContextMenuStrip();

	    //Create some menu items.
	    ToolStripMenuItem openLabel = new ToolStripMenuItem();
	    openLabel.Text = "Open";
	    ToolStripMenuItem deleteLabel = new ToolStripMenuItem();
	    deleteLabel.Text = "Delete";
	    ToolStripMenuItem renameLabel = new ToolStripMenuItem();
	    renameLabel.Text = "Rename";

		openLabel.Click += contextMenuStrip_SubMenuClick;
		deleteLabel.Click += contextMenuStrip_SubMenuClick;
		renameLabel.Click += contextMenuStrip_SubMenuClick;

	    //Add the menu items to the menu.
	    docMenu.Items.AddRange(new ToolStripMenuItem[]{openLabel, 
	        deleteLabel, renameLabel});

	    // Set the ContextMenuStrip property to the ContextMenuStrip.
	    docNode.ContextMenuStrip = docMenu;

	    // Add the TreeView to the form.
	    this.Controls.Add(menuTreeView);
	}
}