#lang racket/gui (define-values [W H] (get-display-size #t)) (define colors '("Black" "Red" "Green" "Blue" "Magenta" "Cyan" "Yellow" "White")) (define (paint-pinstripe canvas dc) (send dc set-pen "black" 0 'transparent) (for ([x (in-range 0 W (/ W (length colors)))] [c colors]) (send* dc (set-brush c 'solid) (draw-rectangle x 0 W H)))) (define full-frame% (class frame% (define/override (on-subwindow-char r e) (when (eq? 'escape (send e get-key-code)) (send this show #f))) (super-new [label "Color bars"] [width W] [height H] [style '(no-caption no-resize-border hide-menu-bar no-system-menu)]) (define c (new canvas% [parent this] [paint-callback paint-pinstripe])) (send this show #t))) (void (new full-frame%))