How is this done?

does anyone know how this is done?
specifically, the way they are opening and closing information and adjusting the scrolling so that the new information is at the top of the screen while appearing to never leave the original frame. For instance, is the information that is opened when you click on the headings being loaded externally into an empty movie clip?
Any suggestions would be appreciated. Even if you can only offer key words for searching other threads - that would be a help.

Thank you