Rated 5 out of 5 stars

I'm amazed at how useful this is. I never liked the back/forward button. So this is a welcomed improvement over it. Good work and better idea!

As REVerdi said there is a need to avoid the appearance of the menu when you're closing a tab by double click. A timer could be added so it handles the event with a small delay that accounts for one used by the double click.

This review is for a previous version of the add-on (2.0.4). 

Double-click problem is fixed

The new release is still in the sandbox, but you can try it if you want.
https://addons.mozilla.org/en-US/firefox/addons/versions/13000
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After a little consideration, a timer seems to be a better option, I'll try to implement it. Thanks for your suggestion.