emacs-28 3b9e60ba2f: ; * src/window.c (Fset_window_start): Mention the effect on vscroll.

[Eli Zaretskii]

branch: emacs-28
commit 3b9e60ba2fad4330682e6fdd15899f0f227a40d7
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    ; * src/window.c (Fset_window_start): Mention the effect on vscroll.
---
 src/window.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/window.c b/src/window.c
index 32e486f9f9..cbb2a9e0e1 100644
--- a/src/window.c
+++ b/src/window.c
@@ -1861,7 +1861,13 @@ point not visible in the window.
 For reliable setting of WINDOW start position, make sure point is
 at a position that will be visible when that start is in effect,
 otherwise there's a chance POS will be disregarded, e.g., if point
-winds up in a partially-visible line.  */)
+winds up in a partially-visible line.
+
+The setting of the WINDOW's start position takes effect during the
+next redisplay cycle, not immediately.  If NOFORCE is nil or
+omitted, forcing the display of WINDOW to start at POS cancels
+any setting of WINDOW's vertical scroll (\"vscroll\") amount
+set by `set-window-vscroll' and by scrolling functions.  */)
   (Lisp_Object window, Lisp_Object pos, Lisp_Object noforce)
 {
   register struct window *w = decode_live_window (window);