Thanks for the contribution.
I've been trying on and off for ages to understand how to get all of the icons in rhythmbox to display using an "official" method as opposed to "blunt instrument".
The "blunt instrument" method is basically to delete /usr/local/share/icons/hicolor and to replace it with a symlink hicolor -> gnome.
I'm sure your article is part of the solution, as is (perhaps) "update-gtk-icon-cache -q -f -t /usr/local/share/icons/hicolor", but any suggestions would be welcome.