I type the url in the address box, say www.linkedin.com Browser tries to establish connection and timouts. I press add-on's button with "X" on it. I see nice box with "Non-proxied page" on it and nice picture like My Computer -> about:newtab. I see www.linkedin.com in the address box. I stay puzzled about how the hell do I enable this add-on for this site.
I do not consider this scenario like anything near to "working". Do developers ever test their products these days?
