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