A couple of additions to the above: After I removed the community-themes package and rebooting everything works as expected and the themes look as intended. No problems at all.
I realized that my custom theme DustyFox, which I thought depended on Dust, was actually modified to the degree that it had nothing to do with Dust any longer. Sorry for the misinformation, therefore. All this seems to indicate, at least to such a layman as I am, that the bizarre behaviour depended on the community-themes package. Thank you for your attention on this report! -- Changing theme causes 100 % CPU & hang https://bugs.launchpad.net/bugs/316575 You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gnome-control-center in ubuntu. -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs