QWindow create/destroy API

From the current documentation and personal experience it is unclear what are the advantages of having the QWindow create/destroy API ? Is it a premature optimization or is there some great benefits? What are those? Disadvantage is that it makes the code seemingly unnecessary more complex? The QWindow can get lazy initialized (::create()) from arbitrary places, potentially making code and behaviour between platform inconsistent. It is likely that even QWidgets and Qt Quick can call create() in different order on window hierarchy - I did not look at this, but it is not impossible.

Investigate and decide if this API makes sense in Qt 6. Perhaps creating QWindow should always acquire a native resource from ctor.