There is copy&pasted code in set_scroll_button, which is apparently
wrong, because it is trying to set scroll method instead of the scroll
button...
https://bugzilla.gnome.org/show_bug.cgi?id=747967
This goes through modifying XI2 device properties, either common ones (eg.
set on every device) or those specific to the libinput X11 driver. Keyboard
repeat/rate are set through core and XKB APIs.
https://bugzilla.gnome.org/show_bug.cgi?id=739397