Thanks for the additional info. It's very clear now. It still sounds like a privilege problem to me. I'll try installing Warhammer on 64-bit Vista and see if I can learn something about it.

"Activate" Warhammer is probably as good a word as any. Actually I don't think there is a perfectly correct word for this, due to changes in Windows over the years. The three terms "activate," "give focus to," and "raise to the foreground" have become pretty complicated. There's a whole chapter about this in the fourth edition of "Programming Applications for Windows" (the standard book on Windows programming from Microsoft) which I think is about 20 pages long!