Robert, I have been trying to figure out how your patch to xwinclip works. In particular, I was wondering how it got notification that the selection had changed when it was owned by another window. I can now sum up your changes in a sentence:
XA_CUT_BUFFER0 is watched for changes and the selection is copied to the Windows clipboard whenever cut buffer 0 is changed. That may not be a completely clean way to solve the problem forever, but it does work, at the very least. Harold