anchor.diff:          radius-2-dx (coerce radius-2-dx 'coordinate)
           radius-2-dy (coerce radius-2-dy 'coordinate)
           start-angle (and start-angle (coerce start-angle 'coordinate))
  -        end-angle (and start-angle (coerce start-angle 'coordinate)) )
  +        end-angle (and end-angle (coerce end-angle 'coordinate)) )
   
     (let ((tr (make-3-point-transformation* 0 0 1 0 0 1
                                             center-x center-y
  
positive.code: ;;; --------------------------------------------------------------------------------------
  ;;;  2001-01-21  GB     fixed bug in (TRANSFORM-REGION T RECTANGLE-SET)
  ;;;                     added some documentation
  
  ;;; ---- TODO ----------------------------------------------------------------------------
  
  
negative.code: 
  (defmethod region-equal ((a standard-rectangle) (b standard-rectangle))
    (multiple-value-bind (x1 y1 x2 y2) (rectangle-edges* a)
      (multiple-value-bind (u1 v1 u2 v2) (rectangle-edges* b)
        (and (coordinate= x1 u1)
             (coordinate= y1 v1)
             (coordinate= x2 u2)
  