Rated 5 out of 5 stars

Campact Menu for 3.5 vs 2.3
https://addons.mozilla.org/ja/firefox/addons/versions/4550
Japanese addons site that requests for login (it is expermental addon but works very well)
The author obviously is the same: the great Milly C
The language of addon is the same of your browser...no Japanese :)

This review is for a previous version of the add-on (2.3.0).