MenuContainer

[James Du]

in API we could find class Component implements interface MenuContainer
My puzzles are
1. why class Frame still declared implements MenuContainer explicitly? isn't it true that a subclass automatically implements all the interfaces that implemented by its superclass?
2. why class Component implements MenuContainer? since only a few special subclass can actually hold a menu component? to be the worst, i find there's only one method "remove" in the MenuContainer is related to the Menu component, and Component provides no real implementation!
Any comments are greatly welcomed
James