The css parser has been modified to parse correctly radial gradients:
background-image: -gtk-gradient (radial,
center center, 0,
center center, 0.8,
from (#000), to (#fff));
The theming engine has been modified to correctly animate these,
as well as transitions between different pattern types.
This type defines a gradient between 2 symbolic colors, with any number
of color stop between these. At the moment it has been put besides
GtkSymbolicColor, although should be completely private, it will likely
need extending in the future for radial gradients.
At some point, it maybe should also be used for images, so painting
both a gradient and an image is consistent.