This can be done by creating transparent windows that cover the screen(s) and using SetSystemUIMode(), but I wouldn't recommend it. If you want your app to stay frontmost you should make it full screen.
That would work correctly for the most part, although to ensure readability/etc, I would replace '3' with '3.0' to ensure that the compiler produces a floating point literal (GCC should be okay, but better safe than sorry *g*).