I'm not entirely sure... I know it worked in 2K, but didn't work for Win9x line, so I'm pretty sure it was in 2K/NT APIs, and not the 3.x/9x/me line. I don't t

I'm not entirely sure... I know it worked in 2K, but didn't work for Win9x line, so I'm pretty sure it was in 2K/NT APIs, and not the 3.x/9x/me line. I don't think it was used by any of MS's internal themes until XP though.