Confirming that the driver from Hardy Proposed fixed the problem. Shadows are back to the normal black and the incorrect drawing of the gtk-window-decorator on unfocused windows does not happen anymore.
GeForce 8400M GS :~$ apt-cache policy nvidia-glx-new nvidia-glx-new: Installed: 169.12+2.6.24.12-17.36 Candidate: 169.12+2.6.24.12-17.36 Version table: *** 169.12+2.6.24.12-17.36 0 500 http://us.archive.ubuntu.com hardy-proposed/restricted Packages 100 /var/lib/dpkg/status 169.12+2.6.24.12-16.34 0 500 http://us.archive.ubuntu.com hardy/restricted Packages -- [nvidia 169.xx] gtk window decorator somtimes draws decoration ugly or not at all https://bugs.launchpad.net/bugs/186382 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs