XPpullMenu()
 Invoke the Pull Down Menu System
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   Function:   XPpullMenu()

               This function invokes the Pull down menu system. The system
               isn't quite exactly SAA compatible, but good enough for
               simple programs. Inspect the XPDEMO program closely would you
               want to use it for your Applications.

   Syntax:     XPpullMenu([n])

   Arguments:  n optionally indicates the Top menu. It defaults to the
               last option.

   Returns:    A code-block, which represents the Menu option chosen
               and should be evaluated.

   Usage:      See XPDEMO