Re:What is Open Source? (Score 1)

Who said anything about Windows? Of course you can't legally fork Windows, because Microsoft has not licensed the Windows source code under its "Shared Source" initiative. You can't fix bugs in Windows, either. But that's irrelevant, because both the article and the post to which I responded talk specifically about source code which Microsoft releases under one of its "Shared Source" licenses. And for that source code, the answer is yes, you can fix bugs and release a competing product.

Can we do so in a manner that no longer requires anyone to pay Microsoft?

If you read the OSI's explanation of the shared source licenses, you'll see that Ms-PL and Ms-RL are more competition-friendly than most of the traditional open source licenses because they also indemnify all contributors against patent infringement. So you wouldn't be legally obliged to pay Microsoft anything if you wanted to rebrand their code and release a competing product.