anchor.diff:  (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 (<= (point-linum point) *start-line-number*)
  +      (move-to-start-point point))
       (when (last-line-p point)
         (line-offset point -1))
       (line-start point)))
  
positive.code: 
  (defun mark-current-line (flag)
    (let ((point (current-point)))
      (when (and (point<= *start-point* point)
                 (not (last-line-p point)))
        (line-start point)
        (with-buffer-read-only (point-buffer point) nil
  
negative.code: 
  (defun mark-lines (test get-flag)
    (save-excursion
      (move-to-start-point (current-point))
      (line-offset (current-point) 2)
      (loop
         (beginning-of-line)
  