anchor.diff:  (defmethod interface-redraw-window (implementation window force)
     (let ((focus-window-p (eq window (current-window)))
           (buffer (window-buffer window))
  -        (screen (lem::window-screen window)))
  +        (screen (window-screen window)))
       (let ((scroll-n (when focus-window-p
                         (window-see window))))
         (when (or (not (native-scroll-support *implementation*))
  
positive.code:                               (point-charpos (window-view-point window))
                                (if focus-window-p
                                    (count-lines (window-view-point window)
                                                 (lem::window-point window))
                                    -1))
          (setf (screen-old-left-width screen)
                (screen-left-width screen))
  
negative.code:             (if (plusp scroll-n)
                  (values (- (screen-height screen) scroll-n) (screen-height screen))
                  (values 0 (- scroll-n))))
          (run-show-buffer-hooks window)
          (disp-reset-lines window)
          (adjust-horizontal-scroll window)
          (screen-display-lines screen
  