anchor.diff:           if evt
            do (typecase evt
                 (glop:key-press-event
  -               (when (= (glop:event-keycode evt) 9) ;ESC
  +               (when (eq (glop:event-keysym evt) :escape)
                    (glop:push-close-event win)))
                 (glop:close-event (setf running nil))
                 (t (format t "Unhandled event: ~A~%" evt)))
  
positive.code: 
  ;; on-event based dispatching test
  (defmethod glop:on-event (window (event glop:key-event))
    (format t "Key ~:[released~;pressed~]: ~A~%" (glop:event-pressed event) (glop:event-keycode event))
    (when (= (glop:event-keycode event) 9)    ;ESC
        (glop:push-close-event window))
    (when (and (glop:event-pressed event) (= (glop:event-keycode event) 41)) ;F
      (glop:set-fullscreen window)))
  
  (defmethod glop:on-event (window (event glop:button-event))
  
negative.code:   (if pressed
        (format t "Key pressed: ~D (~S ~S)~%" keycode keysym string)
        (format t "Key released: ~D (~S ~S) ~%" keycode keysym string))
    (when (eq keysym :escape)
      (glop:push-close-event window))
    (when (and pressed (eq keysym :f))
      (glop::toggle-fullscreen window)))
  
  (defmethod glop:on-button (window pressed button)
  