Some comboboxes (e.g. in chrome://flags) are advertized as…
Notifications of course! Yeah, notifications, the thing that
tells you you have mail, your battery is low, or the dog has
eaten your carpet. This isn't the first time we notice Chromium's
X11 backend is pretty shit.
Anyway, added notifications and splash screens to the list of
unmanaged windows. Also removed utility windows because those
should be managed, but maybe I'm wrong and I'll revert this.
xwm.h was meant to be private, so move it to include/xwayland/xwm.h
We had an ifdef WLR_HAS_XCB_ICCCM in xwayland.h which was easy to move
to xwm, it is not safe to use the WLR_HAS_* in the public headers.
I checked a few of our current users and none rely on xwm.h being
public as expected (rootston, sway, hsroots)
