AS3 Navigation with Submenu - need help

I need help creating a Nav with a submenu. Basically it needs to work like this: When you roll over the first button… the two buttons below it slide down a bit and 4 buttons appear below that… this needs to stay visible as long as you are rolled over the main button or the submenu… I can’t seem to get the events right.

Anyone know of any tutorials? Or show me a quick examples? Thanks!