Form on foreground

Hello,

I want to implement a program with a form which is always on the foreground, even if some games (e.g. DOOM) are started.

I have tried to hold the form in foreground with the API-Function
"SetWindowPos". This function fits my needs so long I not
start a game. Maybe if the DIRECT-X functionality which is used
in the most games is activated my form disappears.

But I want to hold the window of my program always in foreground no matter which application is active.

Thank you in advance!!!