it works Rated 4 out of 5 stars

the button appears in extra bar (at botton of browser window) ONLY when there is a tab with the exact same url as any other

to improve it..., the owner of this addon should allow user option treat urls with anchor or query as the same.

This review is for a previous version of the add-on (0.12.1-signed.1-signed).  This user has a previous review of this add-on.