What is the name of the program for increasing the transparency of windows?

Question

Windows

Good evening! You need a program that can make the window 100% transparent, don't ask why, you just need
to make this window active and then transparent, and you can watch YouTube through it

Answer 1

Wow, simple question... Not only should the window frame be made transparent, but all the elements within it as well; Theoretically: you need to write a program that receives a window, all its elements, and then ... I won’t even say what’s next :) is there such a function as how to correctly apply it to an already running process, etc.