anchor.diff:  
              #:polygonalize
              #:polygon-points
  -           
  +
              #:transformation
              #:areas
              #:positive-areas
  
positive.code: 
  (defpackage :mcclim-bezier
    (:use #:clim #:clim-lisp)
  
    (:import-from #:clim-null
                  #:null-medium)
  
negative.code:   (:import-from #:mcclim-render-internals
                  #:render-medium-mixin
                  #:make-path
                  #:curve-to
                  #:%medium-fill-paths
                  #:%medium-stroke-paths)
  
    (:import-from #:clim-postscript
                  #:postscript-medium
  