It's only a link to the hangouts page, which is reloaded EVERY TIME you open the pop-up. Finally it's better to open the actual web page in a tab of the browser, at least you can pass to another tab without the need to reload the page every time.

This may be a very useful add-on, but it gives me no way of choosing which Google account I want to use or knowing which Google account is being used. Add that capability and I'll try it again. Without that it is useless to me.