A single menu item is defined by the MENUITEM data structure. This structure is used with the MM_INSERTITEM message to insert items in a menu or to query and set item characteristics with the MM_QUERYITEM and MM_SETITEM messages. The MENUITEM structure has the following form:

    typedef struct _MENUITEM { /* mi */
        SHORT  iPosition;
        USHORT afStyle;
        USHORT afAttribute;
        USHORT id;
        HWND   hwndSubMenu;
        ULONG  hItem;
    } MENUITEM;

You can derive the values of most of the fields in this structure directly from the resource-definition file. However, the last field in the structure, hItem, depends on the style of the menu item.

The iPosition field specifies the ordinal position of the item within its menu window. If the item is part of the menu bar, iPosition specifies its relative left-to-right position, with 0 being the leftmost item. If the item is part of a submenu, iPosition specifies its relative top-to-bottom and left-to-right positions, with 0 being the upper-left item. An item with the MIS_BREAKSEPARATOR style in a pull-down menu causes a new column to begin.

The afStyle field contains the style bits of the item. The afAttribute field contains the attribute bits.

The id field contains the menu-item identifier. The identifier should be unique but does not have to be. Just remember that, when multiple items have the same identifier, they post the same command number in the WM_COMMAND, WM_SYSCOMMAND, and WM_HELP messages. Also, any message that specifies a menu item with a non-unique identifier will find the first item that has that identifier.

The hwndSubMenu field contains the window handle of a submenu window (if the item is a submenu item). The hwndSubMenu field is NULL for command items.

The hItem field contains a handle to the display object for the item, unless the item has the MIS_TEXT style, in which case, hItem is 0. For example, a menu item with the MIS_BITMAP style has an hItem field that is equal to its bit-map handle.