Well at least once they pick some open source project, they contribute back the incremental iterations they do.. at least is better than companies that use and

Well at least once they pick some open source project, they contribute back the incremental iterations they do.. at least is better than companies that use and do not contribute back.. I think Xnu is a mix of the CMU kernel + Freebsd kernel stuff + apple specific things like graphical drivers interfaces, etc.. They keep it open the things they borrow and even improve.. im sure X11 improved a lot after apple started using it.. But it still debatable to defend the OS as open source.. just to elaborate a little bit more on my point