Question

I found a thread on MSDN that shows how to add an item to the context menu of a Windows Forms title bar.

Unfortunately it does not show how to register an event with the custom menu item and I have been unable to figure out how to do it. Below is a sample application that can be copied and pasted into a new Windows Forms application. How can I complete the sample?

using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            IntPtr hMenu = GetSystemMenu(Handle, false);
            if (hMenu != IntPtr.Zero)
            {
                var menuInfo = new MENUITEMINFO
                   {
                       cbSize = (uint) Marshal.SizeOf(typeof (MENUITEMINFO)),
                       cch = 255,
                       dwTypeData = "Test Item",
                       fMask = 0x1 | 0x2 | 0x10,
                       fState = 0,
                       fType = 0x0
                   };

                InsertMenuItem(hMenu, 0, true, ref menuInfo);
                DrawMenuBar(Handle);
            }
        }

        [DllImport("user32.dll")]
        static extern IntPtr GetSystemMenu(IntPtr hWnd, bool bRevert);
        [DllImport("user32.dll")]
        static extern bool DrawMenuBar(IntPtr hWnd);
        [DllImport("user32.dll")]
        static extern bool InsertMenuItem(IntPtr hMenu, uint uItem,
                          bool fByPosition, [In] ref MENUITEMINFO lpmii);


        [StructLayout(LayoutKind.Sequential)]
        public struct MENUITEMINFO
        {
            public uint cbSize;
            public uint fMask;
            public uint fType;
            public uint fState;
            public uint wID;
            public IntPtr hSubMenu;
            public IntPtr hbmpChecked;
            public IntPtr hbmpUnchecked;
            public IntPtr dwItemData;
            public string dwTypeData;
            public uint cch;
            public IntPtr hbmpItem;
        }
    }
}

Answer 1

You must override the WndProc method and intercept the id of your new menu.

Try this:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace WindowsFormsApplication11
{
  public partial class Form1 : Form
  {
    public const Int32 WM_SYSCOMMAND = 0x112;
    public const Int32 MF_BYPOSITION = 0x400;
    public const Int32 MYMENU1 = 1000;
    public const Int32 MUMENU2 = 1001;

    [DllImport("user32.dll")]
    private static extern IntPtr GetSystemMenu(IntPtr hWnd, bool bRevert);
    [DllImport("user32.dll")]
    private static extern bool InsertMenu(IntPtr hMenu, Int32 wPosition, Int32 wFlags, Int32 wIDNewItem, string lpNewItem);

    public Form1()
    {
      InitializeComponent();
    }

    protected override void WndProc(ref Message msg)
    {
      if (msg.Msg == WM_SYSCOMMAND)
      {
        switch (msg.WParam.ToInt32())
        {
          case MYMENU1:
            MessageBox.Show("Hi from My Menu 1¡¡¡¡");
            return;
          case MUMENU2:
            MessageBox.Show("Hi from My Menu 2¡¡¡¡");
            return;
          default:
            break;
        }
      }
      base.WndProc(ref msg);
    }

    private void Form1_Load(object sender, EventArgs e)
    {
      IntPtr MenuHandle = GetSystemMenu(this.Handle, false);
      InsertMenu(MenuHandle, 5, MF_BYPOSITION, MYMENU1, "My Menu 1");
      InsertMenu(MenuHandle, 6, MF_BYPOSITION, MUMENU2, "My Menu 2");
    }
  }
}