Hello, as I don't have W10 installed right now, I'll ask: ) If in W10 the window with Metro app become inactive, will the Metro be suspended? Thanks for answer.
Since windowed Modern apps are now handled by ApplicationFrameHost, they all are simply "fooled" into being full-screen for compatibility with older apps, and are still running in AppContainer integrity level. That means any on-screen app will be running regardless if being overlapped with other windows and you make other windows active. I.e. you don't necessarily need a Modern app to be foreground for it to be running. However a modern app will still be tombstoned when minimized unless the app has a background worker process implemented and running.