Creating Drop-down Menu (Intermediate)

[FONT=“Times New Roman”][SIZE=“3”][COLOR=“RoyalBlue”]Hello:

I have read the tutorial on creating drop-down menus which is simple enough but not quite like the one I’m trying to create, which is demonstrated on this site – (top right, only certain buttons have submenus).

How do I go about creating this navigation menu? Is it a movieclip played on rollover or is it ActionScript-heavy? I had originally planned to approach it as a MC played on rollover but I wouldn’t know where to start, as the hard part for me is veiling the submenu items before it unfolds on rollover.