The API spec for java.awt.MenuBar.add(Menu) should state explicitly that if
the menu has been part of another menu bar, that menu is removed from its menu
bar. This is very similar to the spec for Menu.add(MenuItem).
This behavior is reasonable (a menu cannot belong to two menu bars at the same time) and this is what Sun's implementation does. However, it is not formally
required, which caused TCK test exclusions.