如何使用setLevel：不会使窗口高于全屏游戏？

Most games (if not all) do not use Lion's full screen feature. They make themselves full screen using an unofficial method. The problem is - no matter how high I set the level of a window (I'm currently using level 25 - making the window higher than the status bar and its icons) it won't appear over the game. I want to achieve an effect similar to Steam's full screen overlay in game. Is this possible?Most games (if not all) do not use Lion's full