function hide_all () {
	var hEls = document.getElementById("nav").getElementsByTagName("ul");
	
	for (var i=0, len=hEls.length; i<len; i++) {
		if (hEls[i].parentNode) {hEls[i].parentNode.className = "plus";}
		hEls[i].style.display = "none";		
	}
}

function show_element (tmp) {
	 var tmp_id = document.getElementById("nav" + tmp);
	 if (tmp_id.style.display=='block') { 
	 	hide_all ();
	 	}
	 else {
	 	hide_all ();
		tmp_id.style.display = 'block';
	 	if (tmp_id.parentNode) {tmp_id.parentNode.className = "minus";}
	 	}
}