Add comment to line-move re. sit-for.

1 files changed, 2 insertions, 0 deletions

diff --git a/lisp/simple.el b/lisp/simple.el
index ddd2b752a37..6d6c3806889 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -3365,6 +3365,8 @@ Outline mode sets this."
           (set-window-vscroll nil 0)
           (when (line-move-1 arg noerror to-end)
             (when (not forward)
+              ;; Update display before calling pos-visible-in-window-p,
+              ;; because it depends on window-start being up-to-date.
               (sit-for 0)
               (if (and (setq part (nth 2 (pos-visible-in-window-p
                                           (line-beginning-position) nil t)))