anchor.diff:  (defclass standard-polygon (polygon)
     ((points :initarg :points)) )
   
  -;;; ---- 2.5.3.1 Constructors for CLIM Polygons and Polylines  ---------------------------
  +;;; ---- 2.5.3.1 Constructors for CLIM Polygons and Polylines  -----------------
   
   (defun coord-seq->point-seq (sequence)
     (let ((res nil))
  
positive.code:   (with-slots (x y) self
      (and (coordinate= x px) (coordinate= y py))))
  
  ;;; ---- 2.5.3 Polygons and Polylines in CLIM --------------------------------------------
  
  ;; Protocol: 
  (defclass standard-polyline (polyline)
  
negative.code: 			    c))))
  	     (values x1 y1 x2 y2))))))
  
  ;;; ---- Intersection of Ellipse vs. Ellipse -----------------------------------
  
  ;; Das ganze ist so unverstaendlich, ich muss noch mal nach meinen Notizen
  ;; fanden, um die Herleitung der Loesung fuer das Schnittproblem praesentieren
  