INT 16 - PC Tools v5.1+ DESKTOP API - GET KEY
        AX = FFECh
        DS:SI -> FAR routine to ???
        BX = ???
        ???
Return: AX = keystroke
            FFFFh if F10 pressed to go to menu
Notes:  available only when popped up
        invokes INT 28 while waiting for keystroke
        F10 is hotkey to Desktop menu