I couldn't begin to tell you what I did to cause it to go bye bye, it just went away and I was left with a big blank space in the middle of my workspace. I still have my Aux Viewport, I can even drag it into the central area and expand it, but then I lose the Aux Viewport. Also there seems to be no easy way to get back from full screen.
I hate to say it, but it's crap like this that makes me glad DS is free. If I'd paid for software that behaved like this I do believe I'd be pissed. I tried searching the forums, I don't know if anyone else ever tries that but in my experience it is an excercise in futility. It has to be the worst search engine ever.
Anyway, I appreciate any advise on offer. I'm sure that there is some unintuitive sub-menu that will get my Viewport back that I just can't find.