The EnclosureContainer calls isVisible() on the relevant child Component to determine whether the content should be visible or not.
However, in the Component API, visibility is not only defined by isVisible(). There are also the methods isVisibilityAllowed() and isRenderAllowed(). The method determineVisibility() is a summary and yields the overall result whether a Component should be visible or not.
The EnclosureContainer should honor relevantChild.determineVisibility().
In our project a problem occurs because on the relevantChild, we use setVisibilityAllowed(false) to make it invisible, but the EnclosureContainer, or should I say its other contents, remain visible, which we did not expect.