Thunderbird dropdown menu not readable

I use a modified version of the Dust Theme on a fresh Ubuntu Jaunty install.
When I try to enter email recipients in Thunderbird from the provided dropdown list the list background has almost matching colors with the list entries so it can barely be read. It looks like this:

http://bayimg.com/image/japiaaabi.jpg

(Please note I Gauss blurred the entries in the list but the problematic situation is still clearly visible). The list contains multiple entries starting "info@..."

On any other theme when I change the "Input boxes" parameter in the "Appearance" dialog I can produce different text color. Not here. The list stays dark with very dark writing on it. You can make it out if you squint at it but it's very inconvenient. All other menus seem to work fine besides minor already reported bugs (section headings in Thunderbird prefs dialog #346762).