Improve documentation for "other window" scrolling

* doc/emacs/windows.texi (Other Window):
* doc/lispref/windows.texi (Textual Scrolling):
Document scroll-other-window-down.
* doc/lispref/minibuf.texi (Minibuffer Misc):
Cross-reference minibuffer-scroll-window with Textual Scrolling.
* src/window.c (Fother_window_for_scrolling):
Clarify how "other window" is determined in docstring.
(Fscroll_other_window): Simplify docstring, pointing to that of
Fother_window_for_scrolling. (bug#30207)

2 files changed, 8 insertions, 1 deletions

diff --git a/doc/lispref/minibuf.texi b/doc/lispref/minibuf.texi
index 338e03ef74d..889b64af8ae 100644
--- a/doc/lispref/minibuf.texi
+++ b/doc/lispref/minibuf.texi
@@ -2462,7 +2462,7 @@ locally inside the minibuffer (@pxref{Help Functions}).
 @anchor{Definition of minibuffer-scroll-window}
 If the value of this variable is non-@code{nil}, it should be a window
 object.  When the function @code{scroll-other-window} is called in the
-minibuffer, it scrolls this window.
+minibuffer, it scrolls this window (@pxref{Textual Scrolling}).
 @end defvar
 
 @defun minibuffer-selected-window
diff --git a/doc/lispref/windows.texi b/doc/lispref/windows.texi
index f5de2fc90ba..315ffd4f484 100644
--- a/doc/lispref/windows.texi
+++ b/doc/lispref/windows.texi
@@ -4028,6 +4028,13 @@ line reappears after the echo area momentarily displays the message
 @samp{End of buffer}.
 @end deffn
 
+@deffn Command scroll-other-window-down &optional count
+This function scrolls the text in another window downward @var{count}
+lines.  Negative values of @var{count}, or @code{nil}, are handled as
+in @code{scroll-down}.  In other respects, it behaves the same way as
+@code{scroll-other-window} does.
+@end deffn
+
 @defvar other-window-scroll-buffer
 If this variable is non-@code{nil}, it tells @code{scroll-other-window}
 which buffer's window to scroll.