Navbar dropdown menus

[Oddjob]

Can someone give me a detailed explanation on how this is done?

[merk]

It is achieved in a very similar fashion to http://dynamicdrive.com/dynamicindex8/dhtmlwindow.htm (though, it also takes account of each link, and the relative location of those links in the document).

Why do you need to know? It isnt exactly easy to explain unless I know your expertise level.