Rated 5 out of 5 stars

I think, this is newer versions of Popup Inspector 0.1
https://addons.mozilla.org/en-US/firefox/addon/popupinspector/
But sade, that Popup Inspector is not updated, and that the description of Element Inspector is not international.

This review is for a previous version of the add-on (0.0.3.1-signed).