Running application above a game

Hello all.
First of all sorry for my bad english.
I want to create an application which runs above a game in fullscreen? I have tried, the "TopMost = True", but when I run, my game, i can not see my application, and use its bottums. Can you help me, find the right code. Thank you.

The games, are League of Legends, and CSS. If it helps.

Games uses DirectDraw, Direct3D, OpenGL or any other video stream to get dynamic display on your screen.

Check this link : http://stackoverflow.com/questions/4...x-game-overlay