anchor.diff:  (defclass raster-image-port (render-port-mixin basic-port)
     ((width :reader raster-image-port-width)
      (height :reader raster-image-port-height)))
  -   
  +
   ;;; Initialize and Destroy port
   
   (defmethod initialize-instance :after ((port raster-image-port)
  
positive.code: ;;; medium
  
  (defmethod make-medium ((port raster-image-port) (sheet basic-sheet))
    (make-instance 'raster-image-medium :sheet sheet :port port))
  
  
  (defmethod port-set-mirror-region ((port raster-image-port) mirror region)
  
negative.code: 
  (defmethod destroy-port :before ((port raster-image-port))
   (%destroy-all-mirrors port))
  
  ;;; server path
  
  (defun parse-raster-image-server-path (path)
  