From: TwoTailedFox
Owning?
Yes, Microsoft still owns that code, like I own the code I contributed to ReactOS. They (and me too :)) have given an irrevokable, perpetual license to use it, but they still own it.
If this code is open-source/public domain, what is the problem?
There is no legal problem, but it can get confusing. "You guys didn't use any of the leaked source code, so there is no Microsoft code in your OS?" "Well, actually, there are a few bits of Microsoft code". I agree with Steven, it's much better to not have to explain this.
GvG