bug#50269: 27.2; Request: use GTK continuous scroll events for smooth touchpad scrolling

[Alexander Huntley]

> Then I don't think I understand what you'd like Emacs to do in this
> case, and how would that be different from pixel-scroll-mode.  Please
> tell more.
Modern touchpads offer more precision than scroll wheels, so it is possible
(e.g. in Firefox, using libinput drivers) to make the view scroll by
just 1 or 2 pixels using small movements. As a result, the scrolling
corresponds closely to the hand movement on the trackpad. This feels
good (like scrolling on a touchscreen).

Emacs (because it ignores this higher-precision scrolling data) basically
quantizes the available scroll positions, which ought to be continuous.
This makes scrolling on Emacs feel more abrupt than in other apps.

pixel-scroll-mode does not fix this; it just provides an animation between
scroll positions. The available positions remain quantized at line
boundaries.