INT 16 - PC Tools v5.1+ DESKTOP API - DEFINE PULLDOWN MENUS
        AX = FFEEh
        DS:SI -> pulldown menu system description (see below)
Return: AX destroyed
Notes:  available only when popped up
        if the accessory does not need any menu items of its own, it should
          call AX=FFFAh instead
SeeAlso: AX=FFFAh

Format of pulldown menu system description:
Offset  Size    Description
 00h    WORD    offset of menu bar contents (counted string)
 02h    WORD    number of items on menu bar
 04h 10 BYTEs   scan codes for hotkeying to each of up to ten menu items
 0Eh 10 BYTEs   which character to highlight in each menu item (01h=first)
 18h    WORD    offset of first menu definition (see below)
 1Ah    WORD    offset of second menu definition
        ...

Format of menu definition:
Offset  Size    Description
 00h    WORD    offset of menu contents (see below)
 02h    WORD    number of entries in menu
 04h    for each entry:
                Offset  Size    Description
                 00h    BYTE    scancode of Alt-key to invoke entry
                 01h    BYTE    character to highlight (01h=first, etc)
                 02h    WORD    offset of FAR routine to handle selection

Format of menu contents:
Offset  Size    Description
 00h    BYTE    number of lines in menu
 01h    BYTE    width of menu
 02h  N BYTEs   counted strings, one for each line in menu