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

diff --git a/lisp/simple.el b/lisp/simple.el
index ddd2b752a377e2d943d7b2395c676b203e435902..6d6c3806889ac74c5e2d28592f7f39f42f4ce80c 100644 (file)
--- 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)))