The graphics is just a png file with all the needed to make the controls. Honestly, I don't know how the Game Maker UI system works. I shall investigate that. But the png file I guess can be imported and used in any engine.
In this case, I tagged it for Godot because the zip includes a ready-to-use godot resource, that you just drag and change the theme to all the controls in your scene. If I'm able to do such a thing automatically for other engines, I may include those in future updates.