Welcome to Thunderbird Add-ons.
Add extra features and styles to make Thunderbird your own.Close
Rated 5 out of 5 stars
I've posted an updated version (working with Firefox 9) here: https://addons.mozilla.org/en-US/firefox/addon/dictionarysearchupdated/
I'll try to push updates within a day or so of new stable releases of Firefox. Many thanks to the original author.