[Development] Multiple QML engines with different import paths, file selectors, etc

[Ulf Hermann]

> Hi, have you considered how you can keep compatibility, by making this 
> change either opt-in or opt-out? Since it seems the refactoring is 
> already done, it feels like you are making a bet that only has a 
> negative outcome for those porting/trying to keep up. 😊 Good for 
> maintenance, bad for users?

I'm specifically asking here for any use cases that aren't already 
broken. If you have something like that, please let me know. I will 
consider it. I can't really make the whole thing opt-in or opt-out 
without leaving QTBUG-120189 open.

best,
Ulf