The fix is present in Ubuntu Precise and in Linux Mint Lisa. In Oneiric, you can change the GTK theme (right click on desktop ⇒ change background to open the preferences window), or download the fixed GTK debs from Linux Mint repository here and install them manyally with
sudo apt-get install qt4-qtconfig
and set GTK+ as GUI style under System ⇒ Preferences ⇒ QT4 Settings.
Here's some extra, if you wish to work on resolving this problem: