To try the thousands of add-ons available here, download Mozilla Firefox, a fast, free way to surf the Web!
CloseWelcome to Firefox Add-ons.
Choose from thousands of extra features and styles to make Firefox your own.
CloseReview for Color Folders by Dioxaz
Rated 5 out of 5 stars
I'd like to thank Strim for fixing this extension and putting it online, as it appears to work perfectly now! (at least, in Thunderbird 24 and Xubuntu 12.04)
Weirdly, editing the colorfolders.js file as Strim suggested it wouldn't work my case (I even performed a diff showing me the same exact differences as Strim's ones but it still wouldn't work), so that link to a fixed version is more than welcome.
To create your own collections, you must have a Mozilla Add-ons account.