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   MCHOICE()       Sets up a window and does a simple ACHOICE
     Usage         MCHOICE(<arrayname>,<top>,<left>,<bot>,<right>,[<title>] )
     Returns       achoice selection <ExpN>
     Example       (assumes array DOGS[] exists)
                   selection = mchoice("dogs",10,10,20,30,"[DOGS]")
     Notes
                   Bottom of window adjusts to size of array