anchor.diff:  (defmethod medium-draw-bezier-design* (medium design)
     (render-through-pixmap design medium))
   
  +#|
   ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   ;;;
   ;;; Test cases
  
positive.code: (defparameter *r4* (make-bezier-curve* '(100 100 120 150 160 160 170 160)))
  
  (defparameter *r5* (convolute-regions *r2* *r4*))
  
negative.code: 				   (add-points p1 left) (add-points p0 left))
  	      (make-line-segment (add-points p0 left) (add-points p0 right)))))))
  
  (defun area-at-point (area point)
    (let ((transformation 
  	 (make-translation-transformation (point-x point) (point-y point))))
      (transform-region transformation area)))
  
  (defun convolve-polygon-and-segment (area polygon segment first)
    (declare (optimize debug))
    (let* ((points (polygon-points polygon))
  	 (sides (loop for (p0 p1) on (append (last points) points)
  		      until (null p1)
  