CSS Flyout Menu Gets Cut Off By Borders Of Its Container In IE9

I have a flyout menu that (of course) looks great in FF/Chrome, but in IE, it's choking. I have a complete example up on JS Fiddle: http://jsfiddle.net/JXw3S/4/ If you hover over

Solution 1:

#primarymenu has a z-index value set, which is causing the problem in IE9.

http://jsfiddle.net/JXw3S/5/