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 gfw:event-move ((self sheet-event-dispatcher) mirror pnt)
    (enqueue (port self)
             (generate-configuration-event mirror pnt (gfw:client-size mirror))))
  
  (defclass gadget-event (window-event) ())
  (defclass button-pressed-event (gadget-event) ())
  