issue on close second/popup windows Rated 4 out of 5 stars

It's perfect if the developer could fix this bug!!!
http://support.mozilla.com/en-US/questions/796858
BUG: When you open 2 windows or more, it will pop up a warning when I close anyone of it.

This review is for a previous version of the add-on (1.0.3.1-signed). 

We will fix it in the upcoming version.