After a fresh installation of Ubuntu Gnome 15.10, Qt apps like qpdfview or QuiteRSS suddenly stopped inheriting the global GTK theme, in my case Numix. The same is also true for the default Adwaita theme, so most likely it's not the theme's fault. It seems, that these apps always use the Cleanlooks Qt theme, regardless of the present GTK theme.
I've never had any problems with theming on previous installations of Ubuntu Gnome.
qt4-qtconfig and playing with different settings (GUI style: default, cleanlooks or gtk+) didn't have any effect on these apps.
qt4-qtconfig app itself is themed properly. So after selecting a different theme, e.g. "desktop settings (default)" or "windows", the theme of this app changes, but not in
QuiteRSS. The trick with installing
libgnomeui-0 (mentioned here) didn't help either.
Does anyone experience the same and know of a workaround?