BoxUI(Containable) has -> BrownMenuButton(Containable)
You can see that Box is both classes.
Screen is a Surface so it does not inherit that Container but it has a get_rect method which is the requirement for something to be a container. Everything can be a container as long as it has get_rect.
I made two new classes.
Containable
Container
The setup on the main menu now is that:
Screen(Container) has -> BoxUI(Containable)
and
BoxUI(Containable) has -> BrownMenuButton(Containable)
You can see that Box is both classes.
Screen is a Surface so it does not inherit that Container but it has a get_rect method which is the requirement for something to be a container. Everything can be a container as long as it has get_rect.