var selectedSubMenu = null;

$(document).ready(function () {
    $(".bottom_menu_item").hover(function () {

		var subMenu = $(this).children(".submenu:first");
		if (subMenu.length == 1 && !subMenu.hasClass("positionned"))
		{		
			var offset = $(this).children(".menu_links:first").offset();
			var height = $(this).children(".menu_links:first").height();
			var width = $(this).children(".menu_links:first").width();
			var top = offset.top + height + "px";
			var left = offset.left + "px";
			
			subMenu.css({
					'position': 'absolute',
					'left': left,
					'top': top
				}).addClass("positionned");
		}
		
		if (selectedSubMenu != null && (subMenu.length == 0 || subMenu[0] != selectedSubMenu[0]))
		{
			selectedSubMenu.slideUp();
		}
		
		if (subMenu != selectedSubMenu)
		{
			selectedSubMenu = subMenu.slideDown();
		}
    });
});