Please help how to make this work in FullScreen Games

[justachild8]

I really want to use rounded corners but they don't work in fullscreen games. I have come across this: https://spazzarama.com/2011/03/14/c-screen-capture-and-overlays-for-direct3d-9-10-and-11-using-api-hooks/

Can you give idea how to make this work in any fullscreen app?