They're a dime a dozen. If it gets called exclusively from the
input thread, it got one. Hopefully these breadcrumbs will be
enough so people don't lose their way here.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
When running as a dispay server pointer barriers are a server side
feature and requires no client interaction of any sort. This patch
implements pointer barriers that can be used when running as a display
server on the native backend. Running as a display server using the X11
backend is currently not supported.
https://bugzilla.gnome.org/show_bug.cgi?id=706655