The use of multiple viewports, viewport descriptors, drawing operations for multiple viewports is as easy as the use of a single viewport:
> (open-graphics) > (let* ([w1 (open-viewport "viewport 1" 300 300)] [w2 (open-viewport "viewport 2" 200 500)] ; {\em w1\/} and {\em w2\/} are viewport descriptors for different windows [d1 (draw-line w1)] [d2 (draw-line w2)]) ; {\em d1\/} and {\em d2\/} are functions that draw lines in different viewports (d1 (make-posn 100 5) (make-posn 5 100)) ; draws a line in viewport labeled ``viewport 1'' (d2 (make-posn 100 100) (make-posn 101 400))) ; draws a line in viewport labeled ``viewport 2'' ; we no longer have access to viewports 1 and 2, ; since their descriptors were local variables. > (close-graphics) ; removes the viewports