kik wrote:
option 1: supposing it's possible to detect if the Modern Start Screen is currently opened, always go back to the Modern Start Screen in this case.
or option 2: supposing it's possible to detect if the Desktop is currently opened, always go back to the Desktop Screen in this case.
I don't understand - if the Modern Start Screen is already opened, there is nowhere to go - you are already there. Same with the Desktop.
Either way, any such discussion is just theoretical, because there is no way to detect when an application exits. Not without some serious hooking into the OS anyway.
Also, you are assuming a very trivial usage - open application, use it, close it. In practice people run multiple applications simultaneously and close them in arbitrary order. That seriously complicates things.