;Program using Mr Ed that creates a frame, and draws an X to 
;the inside corners of the frame which updates when the frame 
;is resized.
(define lines (lambda (frameWidth frameHeight)

  (define drawWidth 0)
  (define drawHeight 0)

  (define frame (instantiate frame% 
     ("Resize Me") (width frameWidth) (height frameHeight))
  )

  ;; Make the drawing area with a paint callback 
  (define canvas 
    (instantiate canvas% (frame) 
      (paint-callback 
        (lambda (canvas dc) (draw-lines dc))
      )
    )
  )


  ;Create a pen with color red, thickness 2, 
  ;and line type solid.
  (define red-pen 
    (instantiate pen% ("RED" 2 'solid))
  )

  ;; This is the application specific callback
  ;; It is called whenever the frame needs repainting
  (define (draw-lines dc) 
    (set! drawWidth (send canvas get-width))
    (set! drawHeight (send canvas get-height))
     
    ;Set the background color to lavender.
    (send dc set-background 
      (make-object color% 220 200 255)
    )
    (send dc clear)
    (send dc set-smoothing 'smoothed)
  
    (send dc set-pen red-pen)
  
    (send dc draw-line 0 0 drawWidth drawHeight) 
    (send dc draw-line 0 drawHeight drawWidth 0)     
  )

  ;; Show the frame
  (send frame show #t) 

)) 

(lines 300 300)