+ /* compare two images for equality */
+ gboolean (* equal) (GtkCssImage *image1,
+ GtkCssImage *image2);
+ /* transition between start and end image (end may be NULL), returns new reference */
+ GtkCssImage *(* transition) (GtkCssImage *start,
+ GtkCssImage *end,
+ guint property_id,
+ double progress);