CHARACTER string="Hello World! "

   WINDOW(WINdowhandle=wh, Height=1, X=1, TItle="left/right click to rotate left/right, Y-click-position sets milliseconds period")
   AXIS(WINdowhandle=wh, PoinT=20, X=2048, Y, Title='ms', MiN=0, MaX=400, MouSeY=msec, MouSeCall=Mouse_callback, MouSeButton=button_type)
   direction = 4
   msec = 100    ! initial milliseconds
   DO tic = 1, 1E20
      WRITE(WIN=wh, Align='Center Vertical') string
      IF(direction == 4) string = string(LEN(string)) // string ! rotate left
      IF(direction == 8) string = string(2:) // string(1)       ! rotate right
      WRITE(StatusBar, Name) tic, direction, msec
      SYSTEM(WAIT=msec)
   ENDDO
 END

SUBROUTINE Mouse_callback()
   direction = button_type ! 4 == left button up, 8 == right button up
 END