Public bug reported: Wipe our your ~/.cache/thumbnails directory.
Open unity-control-center -> Appearance. Check the contents of ~/.cache/thumbnails. Notice that thumbnails of 256px (the bigger dimension) are placed under the "normal" subdirectory. According to the specs at https://specifications.freedesktop.org/thumbnail-spec/thumbnail-spec-latest.html and https://developer.gnome.org/gnome-desktop3/stable/GnomeDesktopThumbnailFactory.html this is incorrect, the "normal" directory should contain thumbnails of 128px, whereas the "large" directory stores thumbnails of 256px. This means that this cache is at a nonstandard location and as such, is not shared with the rest of the apps. All the other thumbnails I've gathered during years of using my system are under the proper subdirectory. gnome-shell and gnome-control-center also stores them under the proper one, so I suspect it's a downstream Unity bug, not an upstream GNOME one. ProblemType: Bug DistroRelease: Ubuntu 17.04 Package: unity-control-center 15.04.0+17.04.20170402.6-0ubuntu1 ProcVersionSignature: Ubuntu 4.10.0-15.17-generic 4.10.5 Uname: Linux 4.10.0-15-generic x86_64 ApportVersion: 2.20.4-0ubuntu3 Architecture: amd64 CurrentDesktop: Unity:Unity7 Date: Sat Apr 8 11:49:38 2017 InstallationDate: Installed on 2016-11-09 (149 days ago) InstallationMedia: Ubuntu 16.10 "Yakkety Yak" - Release amd64 (20161012.2) SourcePackage: unity-control-center UpgradeStatus: Upgraded to zesty on 2017-04-05 (2 days ago) ** Affects: unity-control-center (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug zesty -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1681059 Title: Misplaces cached background image thumbnails To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/unity-control-center/+bug/1681059/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
