bug#26347: patch for mwheel.el

[Eli Zaretskii <eliz@gnu.org>]

> From: Tak Kunihiro <tkk@misasa.okayama-u.ac.jp>
> Date: Mon, 3 Apr 2017 20:11:45 +0900
> Cc: Kunihiro Tak <tkk@misasa.okayama-u.ac.jp>
> 
> This patch tries to extend a global minor mode `mouse-wheel-mode' and
> makes Emacs scroll both vertically and horizontally by swiping
> `touchpad' or tilting `trackbar’.

Thanks.  This is a substantial contribution, so we will need legal
papers from you to accept it.  Would you like me to send you the form
off-list so you could start your paperwork rolling?

> During not only horizontal scroll but also vertical scroll,
> `auto-hscroll-mode' should be disabled by following three aspects.
> 
> (1) It should be off during horizontal scroll.  If it is on, scope
>     jumps randomly when point is at the edge.  Also, since
>     horizontal scroll does not move point, there will be
>     inconsistency between point and scope, and the inconsistency
>     will result in unexpected shift of the scope.
> 
> (2) It should be off during vertical scroll.  When a buffer is with
>     short and long alternative lines, scope jumps from the end of
>     long line to the end of short line.  Sudden shift of the scope
>     makes edition of a wide document hard.

We don't turn off auto-hscroll-mode when scrolling with the horizontal
or vertical scroll bars, and we don't have the problems you describe
in those cases.  Why is this case different?