anchor.diff:  
   (defmethod gfw:event-resize ((self sheet-event-dispatcher) mirror size type)
     (declare (ignore type))
  +  (setf size (gfw:client-size mirror))
     (let ((sheet (sheet mirror)))
       (if (and sheet (subtypep (class-of sheet) 'sheet-with-medium-mixin))
           (let ((medium (climi::sheet-medium sheet)))
  
positive.code: ;;; mirror methods
  ;;;
  
  (defmethod port-set-mirror-region ((port graphic-forms-port) (mirror gf-mirror-mixin) region)
    (setf (gfw:size mirror)
          (gfs:make-size :width (round-coordinate (bounding-rectangle-width region))
  
negative.code: 
  (defmethod send-selection ((port graphic-forms-port) event string)
    nil)
  
  (defmethod compose-space ((pane gfw-menu-bar-pane) &key width height)
    (declare (ignore width height))
    (make-space-requirement :width 0 :height 0))
  
  ;;;
  ;;; dispatchers and callbacks
  