It would be great for me if the App Structure Panel just allows you to move anything to be within anything else.
It has always felt too restrictive to me and seems to continue to be that in 6.8.0.
Maybe if there is resistance to this idea, there could just an an option we can set that allows it if we choose, which defaults to off.
This is already in 7.0.0 .... 
If you had been at the Meetup, you would have learnt that what you ask for is already available ,,, and more!!!
Instead of fiddling around with 6.8 start using 7b4. same engine different UI.
Getting back to the Meetup .... never mind.
That’s fab news. 
What more could you want than a feature request that is developed instantly? 
One step at a time! 