As Cimi pointed out it seems to be a packaging bug as the theme modules weren't being loaded. I've fixed that by adding back debian/patches/061_multiarch_module_fallback.patch as the theme packages don't have the modules in a versioned library directory. However GTK+ now crashes when loading the modules, so more investigation required.
As Cimi pointed out it seems to be a packaging bug as the theme modules weren't being loaded. I've fixed that by adding back debian/ patches/ 061_multiarch_ module_ fallback. patch as the theme packages don't have the modules in a versioned library directory. However GTK+ now crashes when loading the modules, so more investigation required.