twSaveAreas( aAreas )
 ----------------------------------------------------------------------------
     Save an array of work area information to an internal TSDWIN
     stack. twSaveAreas() saves the same information as that specified
     in twFileStack(). The function may be used as a simple method of
     ensuring that work area information is always restored as you left
     it. After the call, you are returned to the currently selected
     area.

       Arguments:

     aAreas - 'A' Array of work area numbers to be saved. If this is
                  not passed, the work areas from 1 to 15 are saved.
                  Even though Clipper supports 250 work areas, we have
                  decided to limit this function to 15 areas for speed.

       Return:

     Handle for calls to twPopAreas().

       Example:

     nAHandle := twSaveAreas()