have been visiting many flash sites that work in a very attractive way, meaning:
there is a steady background (never disappearing while browsing the site) and all the contents appearing inside a shape (most usually a rectangle)which is the only thing changing while browsing.
I am sure this is a rather stupid q, but would you please give me a hint or redirect me to a relevant thread (can't figure which keywords i should use for searching)?

Thank you in advance.