Rated 5 out of 5 stars

Doesn't work since firefox 36 update .

This review is for a previous version of the add-on (3.2.1-signed). 

Firefox 36 is working for me, with Thumbnail Zoom Plus version 3.2.
Is it not showing pop-ups at all, on any site? Do you see any error indicator? Is there an error message in Tools > Web Developer > Browser Console?

You can reply to me at firefox.add.on@davidadler.name

Thanks,
David