Your question is unclear.
Perhaps if you give the name of the program someone here may have used it and have the answer.
AFAIK, all programs have their own User Interface and each is different from the other so I don't understand what you mean by full-screen Window.
The full screen often refers to I.E. or Windows Explorer which can easily be set.
I'm talking about programs that force you to run in a fullscreen mode. How can I run these programs in a window when they have no option to let me?
I heard that there was a pre-existent option in windows that would let you do it. Am I right, and if so how do I use it with programs? Thank you.