$(document).ready(
	function()
	{
		$("li:has(ul)").click(
			function()
			{
				//hides all other sub menus before displaying a new submenu
				$('#nav li ul').css('display','none');
				//removes the sel tag from all main-item links (level 1 menu items) before adding a new one.
				$('#nav .sel').removeClass('sel')
				
				var p = $(this);
				var ul = p.children("ul");
				//adds .sel class to the clicked menu item
				p.children("a").addClass("sel");
				//displays submenu items
				ul.css("display", "block");
			},
			function()
			{
				var p = $(this);
				var ul = p.children("ul");
			}
		);
	}
);