anchor.diff:  (defun buffer-line-string-set (buffer linum str)
     (buffer-read-only-guard buffer buffer-line-string-set)
     (setf (buffer-modified-p buffer) t)
  +  (when (and (= linum (buffer-mark-linum buffer))
  +             (< (length str) (buffer-mark-linum buffer)))
  +    (setf (buffer-mark-linum buffer) (length str)))
     (let ((line (buffer-get-line buffer linum)))
       (when (line-p line)
         (setf (line-str line) str))))
  
positive.code:             (subseq (line-str line) (+ col n))))
          (setq n 0))
         (t
          (setf (car del-lines)
            (concatenate 'string
              (car del-lines)
  
negative.code: (defun buffer-insert-newline (buffer linum col)
    (buffer-read-only-guard buffer buffer-insert-newline)
    (setf (buffer-modified-p buffer) t)
    (cond
     ((= (buffer-mark-linum buffer) linum)
      (incf (buffer-mark-linum buffer))
      (decf (buffer-mark-col buffer) col))
     ((< linum (buffer-mark-linum buffer))
      (incf (buffer-mark-linum buffer))))
    (let ((line (buffer-get-line buffer linum)))
      (let ((newline
              (make-line line
  