Rather than using the plugin objects constructed() method for doing
setup that requires the MetaScreen, add an explicit start() method
that is called after the screen is set.
The reason for this is that this allows plugin objects to be created
early before the bulk of Metacity setup, which then allows plugins
to affect how the setup happens. (For example, to change the way
that preferences are loaded.)
This is an incompatible change, since 'screen' is now not set in the
constructed method, so the plugin API version is bumped.
https://bugzilla.gnome.org/show_bug.cgi?id=615586
Mutter is a Clutter-based compositing manager. So, remove the code for
the XRender-based compositor, and make it mandatory to have XComposite,
XRender and Clutter.
Run-time support for non-composited operation is left for now.
* src/compositor/mutter/: Move files from this subdirectory into
the main compositor/ directory.
* compositor/compositor-xrender.ccompositor/compositor-xrender.h:
Remove
* include/compositor-clutter.h: Remove this stray file, it had been
replaced with compositor-mutter.h some time back.
http://bugzilla.gnome.org/show_bug.cgi?id=581813
