function displaySubmenu(e){


	$$('.subheaders').invoke('hide');
	$$('.nav_main_sub_dynamic').invoke('hide');

	var nextsub = Event.element(e).up().next('.nav_main_sub');
	
	if (nextsub != null) {
		nextsub.show();
	}

}

function toggleLayers(e){

	if($('nav_main') == e.element()) {
		$$('.subheaders').invoke('show');
		$$('.nav_main_sub_dynamic').invoke('hide');
	}

}

Event.observe(window, 'load', function() {

	var active = false;

	// search for active menuitem	
	$$('#nav_main ul li.level1').each(function(element) {

			if (element.hasClassName('active'))
			{
				$$('#nav_main ul li.active .nav_main_sub').invoke('show');
				active = true;
			}
     });

	 // if user isn't on active menuitem
	 if (!active)
	 {
		 $$('#nav_main ul li .subheaders').invoke('show');
		 $('nav_main').observe('mouseout', toggleLayers);
	 }

	 // listen on mouseover and display submenu
	 $$('#nav_main ul li a.over span').invoke('observe', 'mouseover', displaySubmenu);


});