Rated 1 out of 5 stars

This add-on cannot coexist with Display MUA and Header Tools Extension.
I deleted this add-on and use userChrome.css as follows:
http://forums.mozillazine.org/viewtopic.php?f=30&t=1852065&start=0
http://kb.mozillazine.org/Thunderbird_3.1_-_New_Features_and_Changes#Gaining_Vertical_Space

This review is for a previous version of the add-on (1.2.3).