Some tablets like the Cintiq 24HDT have several mode switch buttons
per group. Those are meant to jump straight to a given mode, however
we just handle cycling across modes (as most other tablets have a
single mode switch button per group).
So spice up the mode switch handling so we handle multiple mode
switch buttons, assigning each of them a mode. If the device only
has one mode switch button, we do the old-fashioned cycling.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/970
Checking the leds is not really accurate, since some devices have mode
switch buttons without leds. Check in the button flags whether they are
mode switch buttons for any of ring/ring2/strip/strip2, and return the
appropriate group.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/952
The end goal is to have all clutter backend code in src/backends. Input
is the larger chunk of it, which is now part of our specific
MutterClutterBackendX11, this extends to device manager, input devices,
tools and keymap.
This was supposed to be nice and incremental, but there's no sane way
to cut this through. As a result of the refactor, a number of private
Clutter functions are now exported for external backends to be possible.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/672
