It turns out this isn't even a bug in mutter. It's actually a bug in mutter-theme-viewer, and a slightly oddity in light-themes.
** Description changed: See screenshot To reproduce: sudo apt-get install human-theme dconf-editor, set org.pantheon.desktop.gala.appearance.theme to "Human" + Set Gtk+ widget theme to radiance. ** Also affects: light-themes (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1090896 Title: metacity themes not coloured correctly To manage notifications about this bug go to: https://bugs.launchpad.net/gala/+bug/1090896/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs