What to do with the 'windows' render loop (single threaded but custom animation driver, so like a mix of basic+threaded).

It is a better alternative than 'basic' when threaded is not wanted since vsync should always be there on most systems with all QRhi backends. Then again it may be a waste of effort and will be rarely used since Vulkan, Metal and D3D (and OpenGL on Windows and most Linuxes) all default to threaded as of now.

Could be that the conclusion is to remove the 'windows' render loop in Qt 6.0.