GNOME 3.30 Mutter Relieves Wayland Code From Depending Upon X11/XWayland

While GNOME's Wayland support has been in great shape with the Mutter compositor, it has depended upon X11/XWayland code even when starting with pure Wayland support. That's now changing and there is also now the optional "--no-x11" flag for starting the compositor without X11 support.

Going back to 2015 has been this bug report about how the GNOME Wayland session will still spawn XWayland even if no X11 applications are needed with parts of the event loop still depending upon X11. Thanks to a big Mutter rework, that is no longer the case.

Hitting the Mutter Git code-base today is a large rework of the internal code to avoid some X11 dependence and better abstract some of the internal workings so it can live happy in an X11-free world. Also as part of today's code is a --no-x11 flag if wishing to start the Mutter Wayland compositor without X11.

Based in part off work achieved during a GSoC project last year is part of the code for allowing XWayland to start on-demand rather than always.

Thanks to this big rework landing, which also bumped the libmutter API to version 3, GNOME 3.30's Wayland support is looking much cleaner.