anchor.diff:                   (dotimes (_ n)
                      (push i (screen-wrap-lines screen)))))
                 (str
  +               (charms/ll:wmove (screen-%scrwin screen) y 0)
  +               (charms/ll:wclrtoeol (screen-%scrwin screen))
                  (setf (aref (screen-old-lines screen) i) str)
                  (let (y2)
                    (multiple-value-setq (curx cury y2)
  
positive.code:                     str
                      (fat-equalp str (aref (screen-old-lines screen) i))
                      (/= (- pos-y start-linum) i))
                 (let ((n (count i wrap-lines)))
                   (when (and (< 0 n) (<= y cury))
                     (incf cury n))
  
negative.code:                        (push i (screen-wrap-lines screen)))))
                   (setf y y2)
                   (incf y))
                 )
                (t
                 (charms/ll:wmove (screen-%scrwin screen) y 0)
                 (charms/ll:wclrtobot (screen-%scrwin screen))
                 (return)))))
      (screen-move-cursor screen curx cury)))
  