C# Signature:

[DllImport("coredll.dll")]
static extern uint AppendMenu(IntPtr hMenu, uint uFlags, uint uIDNewItem, string lpNewItem);

User-Defined Types:

[uFlags]

    uint MF_BYCOMMAND = 0x00000000;
    uint MF_BYPOSITION = 0x00000400;
    uint MF_SEPARATOR = 0x00000800;
    uint MF_ENABLED = 0x00000000;
    uint MF_GRAYED = 0x00000001;
    uint MF_UNCHECKED = 0x00000000;
    uint MF_CHECKED = 0x00000008;
    uint MF_STRING = 0x00000000;
    uint MF_OWNERDRAW = 0x00000100;
    uint MF_POPUP = 0x00000010;

Alternative Managed API:

Do you know one? Please contribute it!

Notes:

None.

Tips & Tricks:

To add a submenu use MF_STRING in conjunction with MF_POPUP passing to the [uIDNewItem] parameter the handle to the submenu parent item as illustrated in the Sample Code section.

Sample Code:

    [DllImport("coredll.dll")]
    static extern IntPtr CreatePopupMenu();

    [DllImport("coredll.dll")]
    static extern uint AppendMenu(IntPtr hMenu, uint uFlags, uint uIDNewItem, string lpNewItem);

    const uint MF_STRING = 0x00000000;
    const uint MF_POPUP = 0x00000010;

    public void CreateMenu()
    {
        IntPtr hMenu = CreatePopupMenu();
        uint flags = MF_STRING;

        AppendMenu(hMenu, flags, 1001, "Simple Menu Item");

        IntPtr subMenuParentItem = CreatePopupMenu();
        flags |= MF_POPUP;

        AppendMenu(hMenu, flags, (uint) subMenuParentItem, "Pop-up Parent Item");
        AppendMenu(subMenuParentItem, MF_STRING, 1010, "Submenu Simple Item");
    }