How to fix broken workspace switcher?

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http://askubuntu.com – My workspace switcher gets broken after each upgrade. It does not have the orange glow around active workspace. Also there is no shadow on the inactive ones (wallpaper does not get greyed out). It works fine in guest session so it has to be related to some config files. Reinstalling does not help. I once deleted most config files and it got back to normal but I'm not sure which files are the culprit. Has anyone experienced this? It has happened to me on multiple machines and in a VirtualBox guest running on Windows. (HowTos)