I like this extension (v1.0.1) which now works also with TB3 beta. Just a small problem. You have named a button button-forward. This makes a problem with standard buttons because one of them has the same name, so in several themes, this makes TB confuses standard icons withs yours. There was not this problem with the previous version (0.9, I think). But anyway, nice extension.
This review is for a previous version of the add-on (1.0.1).