  Generic Clipper ACHOICE function.
  Pass window coordinates (Top, Left, Bottom, Right) and Array to pop. 
APOP will handle the rest.
  The following files should be present.
  FILE_DIZ -- this file
  APOP.PRG -- Main ACHOICE driver
  WINSHADE.PRG -- Paints shadowed border around popped up window
(can see thru the shade).
  SCROLBAR.PRG -- Paints and controls scroll bar to show relative position
inside popped window to complete data available.
  AC_OPT.PRG -- Handles user keystrokes -- automatically called by the
ACHOICE function.

                             --------------
                             |    YOUR    |
  Please review ----->       |  PROGRAM   |
                             --------------
                                   |
                                   |
                                   |
                              -------------
                              |  APOP     |
                              -------------
                                   |
                                   |
      |----------------------------|---------------------------|
---------------            ---------------              ---------------
| WINSHADE    |            |   SCROLBAR  |              |   AC_OPT    |
---------------            ---------------              ---------------
                                                               |
                                                               |
                                                        ---------------
                                                        |  SCROLBAR   |
                                                        ---------------
