http://bugs.winehq.org/show_bug.cgi?id=17423
--- Comment #11 from Stefan Dösinger stefandoesinger@gmx.at 2009-02-21 15:07:02 --- (*) What I wanted to say here: Its quite possible to sneak this hack past the test because there's only a small difference in the test's setup, and a pretty high tolerance for different colors. I think(haven't tested) that the test accepts the results produced by my patch.
If you modify the vertex shader 2 in the test to produce values that are vastly different from the z values the difference becomes obvious.