Rated 3 out of 5 stars

yazan: moojix tarih: Oca. 21, 2010 ·

On Mac and TB 3.0+ you need to install this add-on manually (the 0.0.5.1-mod version):
http://xsidebar.mozdev.org/modifiedmailnews.html#folderpanetools

With 0.0.5.1 version (installed through add-ons from thunderbird menu) i get the same error message
XML Parsing Error: undefined entity
Location: chrome://folderpane/content/folderpanePref.xul
Line Number 255, Column 19:

This review is for a previous version of the add-on (0.0.5.1).