Grafik i Racket

Minimalt Exempel
(define *my-window* (new frame%
[width 300] [height 200] [label "En ram"]))
(define (render-fn canvas dc)
(let-values ([(w h) (send canvas get-virtual-size)])
(send dc draw-rectangle 4 4 (- w 8) (- h 8))))
(define *my-canvas* (new canvas%
[parent *my-window*]
[paint-callback render-fn]))
(send *my-window* show #t)