Create a overlay screen while a game/program is running?

Does anyone know how I can create a screen overlay while a program is running? Mainly while a game is running. If anyone has used xFire or Steam, these use this feature.

I've created a winform which starts the game/program and then minimizes. Could t开发者_如何学运维he overlay be created in the same winform? Thanks for the help! :)

I'm assuming you mean an overlay.

No, there's no way to create one for most games using Windows Forms. You'll need to attach to the DX surface manually. The best way of doing this is to use native C/C++; it's theoretically possible to do this using C# but it would be extraordinarily slow and kludgy.