It's not clear how to use it, no description in the addon page, and I've found nothing in the developer's page (if a content exists, it's not easy to find, the support page only shows support for an extension called Toolbar button, that is not present on Mozilla, and is only available on the support site). Please, add a description and screenshots!

In the sidebar, the storage button, gives an error page, the settings button shows the setting page (By the way, in the settings, this extension is called apt back button), but the dev didn't add options, so it's useless. I don't think this extension is maintained anymore.