Rated 5 out of 5 stars
I have the bad habit of taking habits very quickly. That includes dear Firefox browser, bookmarks sidebar all the same. 'Flat Bookmarks' disturbed me first, breaking ny habits, so I removed it... to realize I was missing 'Flat Bookmarks' !
It's another way of moving around the bookmarks within the sidebar, but it is both smarter and easier, once you get used to it (...), than the usual traveling.
I don't know who the author, Gomita, is, but he/she is certainly quite a clever person: this extension is "smart", and I love smartness :)