function $id(id) {
	return document.getElementById(id);
}
function nav_open(menu) {
	if ($id('lnav_' + menu).style.display == 'block')
		nav_close();
	else {
		nav_close();
		$id('lnav_' + menu).style.display = 'block';
	}
}
function nav_close() {
	eleUL = document.getElementsByTagName('ul');
	for (i=0; i<eleUL.length; i++)
		if (eleUL[i].id.indexOf('lnav_') != -1)
			eleUL[i].style.display = 'none';
}