READ BEFORE POSTING A REVIEW Rated 5 out of 5 stars
BEFORE YOU COMPLAIN IT DOESN'T WORK...
please understand that the dev has allegedly passed away, though this is not confirmed - i do know he is not responding to email
the modded version by the fella in china works with FF release version 23.* - you can find the link here:
direct link: http://sta.sh/0voqv5zgrq2
the only problem i'm personally aware of is a possible issue with restoring closed tabs on occasion
this extension is rather popular and the only one of its kind that offers the features it does - hopefully someone will take over this project