anchor.diff:  (define-key *dired-mode-keymap* "R" 'dired-rename-files)
   (define-key *dired-mode-keymap* "+" 'dired-mkdir)
   
  +(defun move-to-start-point (point)
  +  (line-offset (buffer-start point) (1- *start-line-number*)))
  +
   (defun dired-first-line-p (point)
  -  (same-line-p *start-point* point))
  +  (>= *start-line-number* (point-linum point)))
   
   (defun dired-last-line-p (point)
     (last-line-p point))
  
positive.code: (define-command dired-next-line (n) ("p")
    (let ((point (current-point)))
      (line-offset point n)
      (when (point<= point *start-point*)
        (move-point point *start-point*))
      (when (last-line-p point)
        (line-offset point -1))
      (line-start point)))
  
negative.code: 
  (defun mark-current-line (flag)
    (let ((point (current-point)))
      (when (and (<= *start-line-number* (point-linum point))
                 (not (last-line-p point)))
        (line-start point)
        (with-buffer-read-only (point-buffer point) nil
  