When running rootless as well as rootfull, Xwayland gets its outputs configuration from the Wayland compositor.
When running rootfull, it means that we end up with a large black surface the size of all monitors combined, that's not very convenient and there is no way for set the desired size of the Xwayland window.
Add a new command line option "-geometry" to force a specific mode when running rootfull for the user to specify the root window size to use for Xwayland.
That option has no effect when Xwayland is running rootless.
Signed-off-by: Olivier Fourdan ofourdan@redhat.com Closes: #1338 (closed)