How do you draw on the screen?

[FoxyXXX]

Hello, first of all I wanted to say thank you for this software.
I've been using it for a couple of months and thanks to you I sleep better at night!

I program all sorts of things for games myself,
My question is not so much related to games.
But I was interested in how you draw the "orange effect" on the screen

I will send for information please. Because I told you that it does not interfere with programs that capture the screen and more...

I would appreciate information on the subject. I'm trying to draw on the screen using your method (I'm currently a reverse engineer, but I'd rather ask the smart programmers here)