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 Flat Folder Tree by Topoldo
Rated 4 out of 5 stars
It seems not to work anymore with TB 60. Promotion or collapse of folders has no effect, at least IMHO. I hope it could be updated even if I suspect it will be not.
Topoldo
To create your own collections, you must have a Mozilla Add-ons account.