Finds all matching RC styles for a given widget,
composites them together, and then creates a
#GtkStyle representing the composite appearance.
(GTK+ actually keeps a cache of previously
created styles, so a new style may not be
created.)
Return: the resulting style. No refcount is added
to the returned style, so if you want to save this style around,
you should add a reference yourself.
Finds all matching RC styles for a given widget, composites them together, and then creates a #GtkStyle representing the composite appearance. (GTK+ actually keeps a cache of previously created styles, so a new style may not be created.)