Rated 4 out of 5 stars

yazan: Ibizanhound tarih: Mart 11, 2016 ·

Worked fine for me until FF 45. If I am not mistaken the author is not supporting its development anymore. Anyone knows any alternatives?

This review is for a previous version of the add-on (1.7.5.1-signed). 

yazan: Paolo "Kaosmos" (Geliştirici) tarih: Haz. 24, 2016 ·

This bug should be fixed in 1.7.6 version, released now.
A workaround is to set the preference "extensions.profileswitcher.use_onbeforeunload" to false, but I suggest to try before the new version.

I'm still supporting the development, because this extension is for Thunderbird too, of course when XPCOM/XUL will be dropped support for Firefox will end.