It works everywhere for the vast majority. Apple designs their software for the devices that it is for based in the original version of those devices. If they want to make some button involved in something or something else off the screen, that is perfectly up to them--the OS doesn't revolve only around the screen itself.The control center is meant to be used from wherever you are. Not just at the home screen. It still doesn't work.
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But tons (pretty much most of the other cases) stay in place just fine without some sort of a "pocket" or "lip" that has to be at the bottom of the case to hold it in place. This is a fairly isolated design it seems given that most cases that do cover that part do it because they pretty much cover all non-screen areas (like some Otterbox cases) while pretty much all the other cases don't cover the front of the phone at all.The Belkin Flex cases are gorgeous. Minimal branding, soft yet resilient.
It holds the case into place.
Given the uniqueness of the case unfortunately it seems like it might introduce some practicality issues.