Losing Rollover when mousing onto submenu

[Doubledown]

I'm using images (with rollover images) in my top-level menu. My problem is that when I mouse onto the menu item's submenu, the top-level menu item reverts back to it's original state. I'd like it to stay in it's rollover state until I mouse onto another menu item. What do I need to do?

Thanks for any help.