Forwarding windows to another compositor via Weston

Nicholas Bishop nbishop at
Mon Feb 12 15:18:32 UTC 2018

On Mon, Feb 12, 2018 at 5:48 AM, Pekka Paalanen <ppaalanen at> wrote:
> On Fri, 9 Feb 2018 18:30:13 -0500
> Nicholas Bishop <nbishop at> wrote:
> > Hi,
> >
> > Is there a way to run Weston as a nested compositor without the root
> > window? My use case is running a parent compositor that doesn't support
> > Xwayland, so I'd like to use Weston for X applications and have the
> > resulting windows appear as regular windows within the parent compositor.
> >
> > Is something like this possible (or even reasonable)? Alternative
> > suggestions welcome too :)
> Hi,
> Weston's Wayland backend has no such code, it would need to be written.
> Essentially one would implement assign_planes hook that would make sure
> to leave nothing on the primary plane. This would need code to forward
> each wl_buffer type in its appropriate way and all the window
> management.
> However, wanting to forward X11 windows would be problematic, because
> in rootless mode you lose the control of absolute positions and you
> basically lose a lot of window management behaviour that X11 clients
> expect to work. This happens because Wayland for the desktops is
> specifically designed to avoid many features the X11 clients are
> accustomed to, like being able to control window position and
> z-order, and grab input devices.
> My personal opinion is that effort would be better spent in helping the
> parent compositor project to support Xwayland instead.
> Thanks,
> pq

Thanks for the insight, that's very helpful. If I go down the route of
trying to add Xwayland support to the parent compositor, do you have
any recommended resources such as documentation or a simple compositor
with Xwayland support to guide me?


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