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 Extra Folder Columns by thomas_besser
Rated 3 out of 5 stars
I like this extension.
But since TB 3.1 it can no longer be installed as global extension (see http://kb.mozillazine.org/Installing_extensions#Global_installation). TB reports it as 'incompatible' with this version (tried TB 5, 6 and 7).
Single-user Installation works!?
Support for global installation is something that was removed from Thunderbird, Firefox etc (i.e. gecko). It is not something that can be affected by this extension.
To create your own collections, you must have a Mozilla Add-ons account.