Add a CSS property to control style transitions. https://bugzilla.gnome.org/show_bug.cgi?id=619025
Extend the existing support for -st-shadow to apply to the background, background-gradient and border properties in addition to background-image. https://bugzilla.gnome.org/show_bug.cgi?id=613832
The idea behind this move is that we have a lot more control over rendering if StWidget isn't a big pile of actors, and things are more efficient. https://bugzilla.gnome.org/show_bug.cgi?id=607500