YAHOO.util.Event.onContentReady("navmenu", function () {
    var oMenu = new YAHOO.widget.MenuBar("navmenu", { 
		autosubmenudisplay: true,
		constraintoviewport: false,
		showdelay: 0
	});
    
	function onMenuBarBeforeShow() {
		var oParent = this.parent;
		if (oParent && oParent instanceof YAHOO.widget.MenuBarItem) {
			this.cfg.setProperty("zindex", 3);
		}
	}

	oMenu.subscribe("beforeShow", onMenuBarBeforeShow);

    oMenu.render();
});