private void MyPopupEventHandler(System.Object sender, System.EventArgs e)
 {
    // Define the MenuItem objects to display for the TextBox.
    MenuItem menuItem1 = new MenuItem("&Copy");
    MenuItem menuItem2 = new MenuItem("&Find and Replace");
    // Define the MenuItem object to display for the PictureBox.
    MenuItem menuItem3 = new MenuItem("C&hange Picture");

    // Clear all previously added MenuItems.
    contextMenu1.MenuItems.Clear();
 
    if(contextMenu1.SourceControl == textBox1)
    {
       // Add MenuItems to display for the TextBox.
       contextMenu1.MenuItems.Add(menuItem1);
       contextMenu1.MenuItems.Add(menuItem2);
    }
    else if(contextMenu1.SourceControl == pictureBox1)
    {
       // Add the MenuItem to display for the PictureBox.
       contextMenu1.MenuItems.Add(menuItem3);
    }
 }

//引入命名空间
using System;
using System.Drawing;
using System.Windows.Forms;
   
class ContextMenuAdd: Form
{
     MenuItem miColor;
   
     public static void Main()
     {
          Application.Run(new ContextMenuAdd());
     }
     public ContextMenuAdd()
     {
          Text = "Context Menu Using Add";
   
          ContextMenu  cm = new ContextMenu();
          EventHandler eh = new EventHandler(MenuColorOnClick);
   
          cm.MenuItems.Add("Black",   eh);
          cm.MenuItems.Add("Blue",    eh);
          cm.MenuItems.Add("Green",   eh);
          cm.MenuItems.Add("White",   eh);
   
          foreach (MenuItem mi in cm.MenuItems)
               mi.RadioCheck = true;
   
          miColor = cm.MenuItems[3];
          miColor.Checked = true;
          BackColor = Color.FromName(miColor.Text);
   
          ContextMenu = cm;
     }
     void MenuColorOnClick(object obj, EventArgs ea)
     {
          miColor.Checked = false;
          miColor = (MenuItem) obj;
          miColor.Checked = true;
   
          BackColor = Color.FromName(miColor.Text);
     }
}