Frame events group logically connected pointer events. It makes sense to make
the backend responsible for sending frame events, since once the events are
split (ie. once the frame events are stripped) it's not easy to figure out
which events belongs to which frame again.
This is also how Weston handles frame events.
Fixes https://github.com/swaywm/wlroots/issues/1468
In pointer.c, some axis event was emitted even if the event pointer did not have
current axis.
In X11 backend pointer scroll events seem to be composed of both BUTTON_PRESS
and BUTTON_RELEASE. Therefore we should skip one of them (RELEASE) to avoid
event duplication.
- 'libinput' (backend's) to libinput_context
- 'device' (libinput_device) to libinput_dev
- 'dev' (wlr_device) to wlr_dev
- 'devices' lists tangling of libinput devices to wlr_devices
- 'devices' list of wlr_devices in backend state to wlr_device_lists
