Be careful with old versions!
These versions are displayed for reference and testing purposes. You should always use the latest version of an add-on.
Full list of fixes: http://bri.kz/acr07bugs
* Enable and Disable buttons are no longer shown at the same time in Firefox 4's Add-ons Manager details view
* Fix button sizing issues in Firefox 4
* Fixed issues with Thunderbird compatibility
Also adds a number of new locales.