How is a non-standard interface for programs created?

Question

User interface

I understand that the question is very noob, but I am engaged in web programming, everything is simple there: controls can be styled as you like. But how to create a Windows program with a style, for example, like WinAmp? Or many crackers and patchers for paid programs also look quite unusual. On what is all this created?

Answer 1

Hundreds of ways.
It is possible to rivet on pure WinAPI.
And 20 years ago I did this in Delphi, there are special components for this.

Answer 2

Just like on the web, markup languages.
List of user interface description languages

Answer 3

non-standard interface for programs

It depends on what is considered standard.
For example, in Windows, system libraries are most often used to display windows.
But you can include a third party library.
Or completely write the window code yourself.