Since style_class and pseudo_class are space-separated lists of names,
add new methods to add and remove individual names rather than just
re-setting the entire name.
Update existing code to use the new pseudo-class methods where
appropriate. In some cases, this may result in actors having multiple
pseudoclasses where previously they only had one at a time, but there
don't seem to be any visible differences.
(There are some places that could usefully use the new style_class
methods as well, but this patch doesn't change them.)
Also, update test-theme.c to test the new methods.
https://bugzilla.gnome.org/show_bug.cgi?id=604943
909b5ec43c