Fix embed mode detection
Review Request #123680 - Created May 8, 2015 and submitted
Wow, I have no idea how this happened. I wrote an big test case and spent a lot of time playing with tabs. Stephan Binner even told me about this a month ago, but I didn't quite understand the problem...
Broken embed mode detection means that the tabbed interface is disabled. It actually made it into release... ugh
Tabs work again.