Wayland and Weston 1.6.0 released

xdg-shell is not a stable protocol extension yet! you even have to explicitly invoke a "use_unstable_version" method on it with the version that your client was compiled against (which must precisely match the version that the compositor was compiled against) to make use of it.

This is also why it is being carried by downstream compositors and toolkits at the moment instead of being carried in upstream Wayland. Once it's stable then it will get upstreamed and frozen, and its out-of-band version negotiation mechanism will go away in favour of Wayland's existing built-in interface version negotiation mechanism.

xdg-shell is intended to eventually replace the core protocol's wl_shell interface which was found to have a racy design (racy in the sense that it causes display corruption, not memory corruption, thankfully). More details here:

http://blog.mecheye.net/2014/06/xdg-shell/

Protocol spec:

http://cgit.freedesktop.org/wayland/weston/tree/protocol/...