bug#65070: 29.1; (Only on Windows) Both touchpad scroll gestures scroll the screen up and down.

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sat, 19 Aug 2023 01:49:08 +0900
> From: Kazuhiro Ito <kzhr@d1.dion.ne.jp>
> Cc: Hiroya Ebine <hiroya.ebine1@gmail.com>,
>   Eli Zaretskii <eliz@gnu.org>, max@mal-richtig.de
> 
> > 1. c-h i (open any vertically long document)
> > M-> (move to the bottom of the document) 3.
> > 3. perform the scroll down gesture on the touchpad.
> > 
> > Then you will see the screen scroll up.
> > Either scroll down or scroll up, whichever you do, the screen will scroll up.
> 
> I noticed that when I input wheel-down with touchpad, line count is
> set to negative value, which should be positive integer.
> 
> (let ((event (read-event)))
>   (cons (car event) (event-line-count event)))
> 
> ;; Input via touchpad
> (wheel-down . -3)
> (wheel-up . 3)
> 
> ;; Input via mouse wheel
> (wheel-down . 1)
> (wheel-up . 1)

Thanks.  Can you show the complete data of the events in both the
mouse and the touchpad cases?

And I wonder how come the results are different: the Windows events
reported to Emacs are the same events, and are processed by the same
code.  Hmm...