Rated 4 out of 5 stars
v1.3.6; FF 12.0 on OS X [10.6.8]
Doesn't display correctly, only half of the bookmarks show. Close window & open a new one and it works correctly.
Used Anders Labich's solution below and installed v1.3.3 & set automatic updates to off. Works perfectly every time FF is launched!
-1 star but still a great add-on.