The Director is the component which takes care about going back and forth between scenes.
The Director is a shared (singleton) object. It knows which scene is currently active, and it handles a stack of scenes to allow things like "scene calls" (pausing a Scene and putting it on hold while other enters, and then returning to the original). The push, replacement or end of the current scene is made by director.
The Director is also responsible of initializing the main window.