anchor.diff:                (descent (text-style-descent style pane))
                 (height (+ ascent descent))
                 (y (line-vertical-offset pane view line-number))
  -              (x (offset-x-displacement pane line-beg offset)))
  +              (x (offset-x-displacement pane view line-beg offset)))
            (values x y height style-width))))))
   
   ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  
positive.code:            while go-again
             if (eql object #\Tab)
             do (progn (incf displacement (string-size array))
                       (incf displacement (tab-width pane))
                       (setf (fill-pointer array) 0))
             else if (and (characterp object)
                          (not (eql object #\Tab)))
  
negative.code:                  (* text-style-height
                      (- line-number (1- found-line-number))))))))))
  
  (defun offset-x-displacement (pane view line-beg-mark offset)
    (with-sheet-medium (medium pane)
      (let ((displacement 0)
            (style (medium-text-style pane)))
  