This commit introduces a new flavour for Clutter, that uses GDK
for handling all window system specific interactions (except for
creating the cogl context, as cogl does not know about GDK), including
in particular events. This is not compatible with the X11 (glx)
flavour, and this is reflected by the different soname (libclutter-gdk-1.0.so),
as all X11 specific functions and classes are not available. If you
wish to be compatible, you should check for CLUTTER_WINDOWING_X11.
Other than that, this backend should be on feature parity with X11,
including XInput 2, XSettings and EMWH (with much, much less code)
https://bugzilla.gnome.org/show_bug.cgi?id=657434
Cogl has now been split out into a standalone project with a separate
repository at git://git.gnome.org/cogl. From now on the Clutter build
will now simply look for a cogl-1.0 pkg-config file to find a suitable
Cogl library to link against at build time.
