function menu_show(id_num){

	//alert(id_num);
	var test = document.getElementById('nav_item_'+id_num).className;

	if(test != 'selected_nav'){

		document.getElementById('nav_item_'+id_num).className = 'selected_nav';
		document.getElementById('arrow_'+id_num).style.display = '';

	}


}

function menu_hide(id_num){

	document.getElementById('nav_item_'+id_num).className = 'un_selected_nav';
	document.getElementById('arrow_'+id_num).style.display = 'none';
	
}