user32:clipboard winex11.drv (KDE) interference

[Esme Povirk (they/them)]

Can this situation happen on Windows? From what I've seen, Windows
code has no way of handling these random OpenClipboard failures. If it
really works that way, it seems like a design flaw in the Windows API
that we can't fix. It wouldn't be the first of those.

On Windows, we could fix this by running the tests on a separate
desktop (assuming the software that's intefering doesn't follow us
there), but that wouldn't help in Wine.