bug#28342: 26.0.50; (OSX) Jumpy Scrolling using Trackpad

[Eli Zaretskii]

> Date: Wed, 06 Sep 2017 19:55:41 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 28342@debbugs.gnu.org, jamesn@fastmail.com, charles@aurox.ch,
>       james@jojojames.com
> 
> > (setq scroll-margin 5)
> > (setq scroll-preserve-screen-position 1)
> > (setq mouse-wheel-scroll-amount '(1))
> > 
> > Open a large file. Make sure you're at the start of the file
> > 
> > M-<
> > 
> > Scroll down with the mouse wheel and within a few clicks point jumps to the 
> > middle of the screen. A few more
> > and it jumps to the end of the file.
> 
> Even simpler: after evaluating the first 2 of the above 3 settings,
> visit xdisp.c, then type this twice:
> 
>   C-u 1 C-v
> 
> After you type this the second time, Emacs will infloop.
> 
> This bug is already present in Emacs 25.1.
> 
> I will look into this when I have time.  Thanks for the recipe.

Should be fixed now on the master branch.