anchor.diff:                 (vector-push-extend width widths))
                 (object
                  (multiple-value-bind (w)
  -                   (text-size stream object
  +                   (font-replacement-text-size stream object
                       :text-style text-style)
                    (incf width w)
                    (vector-push-extend width widths)))
                 (t
                  (multiple-value-bind (w)
  -                   (text-size stream stroke-string
  +                   (font-replacement-text-size stream stroke-string
                       :start start :end end
                       :text-style text-style)
                    (incf width w)
  
positive.code: ;;; utilities needed for the Drei redisplay engine
  
  (in-package :drei)
  
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;;;
  
negative.code: 	    do (return (aref (stroke-widths stroke) next))
  	  when (<= start pos end)
  	    do (return (+ width
  			  (font-replacement-text-size stream string
  				                      :start start
  				                      :end pos
  				                      :text-style (merge-text-styles
  						                   (face-style
  						                    (drawing-options-face
  						                     (stroke-drawing-options stroke)))
  						                   (medium-merged-text-style (sheet-medium stream)))))))))
  
  (defgeneric offset-to-screen-position (pane view offset)
    (:documentation "Returns the position of offset as a screen
  