This also slightly affects Qt apps to the degree that their respective icons are not shown anymore in the panel (and windowframe). This also seems to happen only in Gnome as Kubuntu users don't report any problems.
temporary fix: (downgrade) sudo apt-get install xserver-xorg-core=2:1.3.0.0.dfsg-12ubuntu8
This also slightly affects Qt apps to the degree that their respective icons are not shown anymore in the panel (and windowframe). This also seems to happen only in Gnome as Kubuntu users don't report any problems.
temporary fix: (downgrade) xorg-core= 2:1.3.0. 0.dfsg- 12ubuntu8
sudo apt-get install xserver-