detecting tablet mode

[Marco Martin]

Hi all,
one thing i wanted to look into, is to detect when a trasformable laptop goes 
in tablet mode from applications, so that plasmashell and kirigami apps can 
adapt themselves and do things(tm)
KWin does that (on wayland) already, and i see it uses libinput for that, like 
i seem to evince from this recent commit (and the logic when to show the on 
screen keyboard)
https://cgit.kde.org/kwin.git/commit/?
id=ac2f41c86d3b5b13ba3655e6c2f17f59a4cb7f01

would a normal application use libinput too or is something reserved to the 
compositor?
what would be the right way(tm) there? a dbus signal from KWin?

-- 
Marco Martin