Add a new command line option "-host-grab" to disable the keyboard shortcuts and confine the pointer on the host so that Xwayland can receive all keyboard events.
This is useful when running a complete desktop environment within Xwayland rootful.
Use CTRL+SHIFT to release the keyboard and pointer.
This option has no effect when running rootless.
Signed-off-by: Olivier Fourdan ofourdan@redhat.com