anchor.diff:             (gl:vertex 0.75 0.75 0)
              (gl:vertex 0.25 0.75 0))
            (gl:flush)
  -         (glop:swap-buffers win))))+         (glop:swap-buffers win))))
  
positive.code: 
  (defmethod glop:on-button (window pressed button)
    (declare (ignore window))
    (if pressed
        (format t "Button pressed: ~S~%" button)
        (format t "Button released: ~S~%" button)))
  
  (defmethod glop:on-mouse-motion (window x y dx dy)
    (declare (ignore window x y dx dy))
  
negative.code: (in-package #:glop-test)
  
  (defmethod glop:on-key (window pressed keycode keysym string)
    (format t "Key ~:[released~;pressed~]: ~D (~S ~S)~%" pressed keycode keysym string)
    (when (eq keysym :escape)
      (glop:push-close-event window))
    (when (and pressed (eq keysym :f))
  