Rated 5 out of 5 stars

Works well in Firefox 3.5 and latest nightly build (forced install). Tooltip says up as long as I want it to.

P.S. Please change the default preview image for this addon. It was very confusing the first time I tried to install it -- especially since my nightly build wasn't officially compatible.

This review is for a previous version of the add-on (1.0). 

Indeed

You're right. I've replaced it by a customized tooltip.