anchor.diff:  (defmethod glop:on-key (window state key)
     (format t "Key: ~S~%" key)
     (when (eql key #\Escape)
  -    (glop:push-close-event window))
  -  (when (and (eql key #\f) (eql state :press))
  -    (glop:toggle-fullscreen window)))
  +    (glop:push-close-event window)))
   
   (defmethod glop:on-button (window state button)
     (declare (ignore window state))
  
positive.code:            (gl:vertex 0.25 0.75 0))
           (gl:flush)
           (glop:swap-buffers win))))
  
negative.code:          (glop:swap-buffers win))))
  
  (defun test-gl-hello-fullscreen ()
    (defmethod glop:on-key :after (window state key)
      (format t "Key: ~S~%" key)
      (when (and (eql key #\f) (eql state :press))
        (glop:toggle-fullscreen window)))
    (glop:with-window (win "Glop test window" 800 600 :fullscreen t)
      (format t "Created window: ~S~%" win)
      ;; GL init
  