Get the court to order discovery on all of your computers. They could probably also get subpoenas for the source code hosting sites to reveal relevant access logs. Or someone could admit to reading the source code someplace public, like a bug tracker. Or they could argue that the choice of variable names and minor details of algorithm details are too close to be coincidence. A jury convicted Google because of rangeCheck, after all.

> 2. If microsoft sued wine devs it would be horrible for Microsofts public image. They won't do it.

No it wouldn't, particularly not if they had a strong case (e.g., someone bragging about it). If you think MS looks bad for suing people for stealing the code, then you'd have to think the FSF looks bad for suing people for violating the GPL and stealing the code of, say, Linux.

> 3. I hope the WINE devs don't listen to you.

I hope they don't listen to you. The repercussions are quite large--it's not unimaginable that shutting down the WINE project could result from a lost case. These cases do happen, and defendants do lose (Oracle v. Google is a notable recent one, and that's based on IMHO fairly weak evidence). There's a reason that projects that do major reverse engineering for interoperability have rather elaborate procedures for doing so.