Public bug reported: I've found this warning in .xsession-errors. It seems to be the culprit:
Avertissement du gestionnaire de fenêtres : Impossible de charger le thème « Adwaita » : Ligne 119 caractère 50: Impossible de comprendre le composant de couleur « custom(wm_title_highlight,gtk:base » dans la spécification de couleur A rough translation would be: Window manager warning: Unable to load the « Adwaita » theme : Line 119 character 50: Unable to parse the color component « custom(wm_title_highlight,gtk:base » in the color specification ProblemType: Bug DistroRelease: Ubuntu 11.10 Package: gnome-shell 3.1.3-0ubuntu3 ProcVersionSignature: Ubuntu 3.0.0-8.11-generic-pae 3.0.1 Uname: Linux 3.0.0-8-generic-pae i686 Architecture: i386 Date: Thu Aug 18 09:51:06 2011 InstallationMedia: Ubuntu 10.04.1 LTS "Lucid Lynx" - Release i386 (20100816.1) SourcePackage: gnome-shell UpgradeStatus: Upgraded to oneiric on 2011-08-12 (5 days ago) ** Affects: gnome-shell (Ubuntu) Importance: Undecided Status: New ** Tags: apport-bug i386 oneiric -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/828543 Title: Adwaita window decoration broken in gnome-shell To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-shell/+bug/828543/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs