Please read! Rated 4 out of 5 stars
It seems the developer (Ithinc) is not gone, deceased or what so ever. According his/her comment below and at the top of this add-on description he/she wrote this add-on will be updated at the end of September. In the meantime I advise everyone to use a fork called Tab Utilities Phoenix (by Stux) https://addons.mozilla.org/en-us/firefox/addon/tab-utilities-phoenix/. I advise Ithinc and Stux to work together to make sure there is only one solid, regularly updated add-on.This review is for a previous version of the add-on (1.5.1).