My question was how to leave and get back to a running/suspended/whatever modern app. Mousing to the upper left corner does nothing at all for me. No popups, nada. I'll take a look at the properties sheet for the start screen (when I figure out where it is LOL!) Edit: Found it, but the second box in the navigation tab of the properties window, switch between running apps when I click the top left corner, is grayed out. Now what?
Maybe I misunderstood what I read about modern apps in a couple of other places. I was under the impression they were suspended -- i.e., not running but not closed -- when you moved away from them. Basically just like a smartphone. That link in the post above says, "When you stop using an app, Windows leaves it running in the background and then, after a while, closes it for you."
So, for example, when I run Windows Update from the desktop, updates will download in the background. What happens when I run the modern app version of Windows Update? I got started on this train of thought because a few days ago I started Update by searching for it on the start screen instead of going through the control panel. That started the modern app version. The 8.1 update hadn't been pushed to me yet but there was a bunch of other updates available. Started to download them and went back to business. An hour later, I went back to Update again, and the progress bar was still where it was when I left the app.
I can't believe that you can't have a modern app continue to work in the background while you're doing something else. So I must be doing something wrong.