Scrolling using touch pad only partially works

ryanprior commented 3 years ago

Summary

Scrolling a buffer using the touch pad doesn't work for the most part. Sometimes Emacs will scroll, but in large jumps that are not predictable or useful.

Software and hardware versions

M-x emacs-version says:

GNU Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.20, cairo version 1.16.0)
guix show emacs-next-pgtk says:

version: 28.0.50-0.3df4ca4
Operating system is elementary OS 5.1.7 Hera
Hardware is a 2019 Dell XPS 13 with no peripherals attached

How to trigger the issue

Start Emacs using: guix environment --pure --ad-hoc emacs-next-pgtk -- emacs -Q

Load a buffer and scroll using a touch pad.

Expected behavior

Emacs should begin scrolling the buffer right away.

Observed behavior

Emacs mostly does not respond to touchpad scrolling at all. On occasion the buffer scroll position jumps suddenly in the direction I'm trying to scroll.

Workarounds

Keyboard scrolling works: I can scroll the buffer just fine using the C-v, M-v, etc
GTK scrollbar works
Touch-pad scrolling works in upstream Emacs 27 and 28

I don't observe any unusual or undesirable behaviors when scrolling using those methods. Only scrolling using the touch pad in the pgtk build seems to be affected.

P.S.

THANK YOU for working on this fantastic software!

masm11 commented 3 years ago

Thank you for the report with detail.

I fixed it. Please try the latest feature/pgtk on savannah.

ryanprior commented 3 years ago

Your patch fixes the issue for me. I've submitted a patch to update the Guix package as well: https://issues.guix.gnu.org/44934

Thank you again!

masm11 / emacs