awful

Nothing loads inside the border... it's just a white page.

All I get is a pretty border. I can't see my contacts, messages, nothing. All I get is a blank white pane.

Didn't work.

Shortly after installing and trying out this add-on, someone named "Barbara" showed up in my contact list. I do not know this person. I have never accepted this person. I am not even sure this is a person. In other words, either this add-on has been compromised by malware, or it IS malware. I uninstalled it immediately, and I suggest others not to touch this either.

puts the hangouts website in the sidebar, it's completley unusable.

I keep getting an error that Firefox is blocking cookies and it's only blocking third party. If I navigate to hangouts.google.com and have no problem signing in.

A pinned tab + setting ctrl-tab to visit tabs in most recent order is pretty much superior - this addon's pop-out widget just displays the hangouts page, but it reloads every time you open it, so a very nice delay there. It also asks for the "read all webpage data" permission for some reason.

Unfortunately that seems to be what all these hangouts plugins do...

Maybe add some way to quickly respond to messages when you get one, like the respond-in-the-notification thing that Android apps tend to have? This would be somewhat complicated I imagine, but it would make for a killer extension.