In the wayland tablet input model, compositor and clients may
recognize the different physical styli in use, even if those are
used across compatible tablets.
This object is intended to be used as a persistent memory of
which stylus was used with which tablet. So you 1) can associate
tools and devices when such combination happens, and 2) query the
styli that were previously used with a tablet when it is detected/
plugged.
These associations are stored in two keyfiles in
~/.cache/gnome-control-center/wacom/, one for tablets and other
for styli.
