bug#51891: 29.0.50; [PATCH] Pixel delta support for wheel events on X

[Eli Zaretskii]

> From: Po Lu <luangruo@yahoo.com>
> Cc: rpluim@gmail.com,  51891@debbugs.gnu.org
> Date: Thu, 18 Nov 2021 17:17:25 +0800
> 
> >> An amount of scrolling that would previously generate a `mouse-4' or
> >> `mouse-5' event.
> 
> > That doesn't really answer my question.  Let me ask it differently:
> > how does "scroll unit" differ from "every time the wheel is moved"?
> 
> Basically, even tiny movements of the scroll wheel will cause XInput 2
> to generate wheel events.  This makes the behavior stay like the
> original by default, where you have to scroll 96 or so pixels before a
> wheel event is actually sent.  (This is generally true, but certain mice
> may behave differently.)

Then the first sentence should probably be

  Non-nil means send a wheel event only for scrolling at least one screen line.