var lastone_opened = '';
function showmenu(elem) {
	if(document.getElementById(elem).style.visibility != 'visible') {
		if(lastone_opened != '') {
			document.getElementById(lastone_opened).style.visibility = 'hidden'; 
		}
		document.getElementById(elem).style.visibility = 'visible';
		lastone_opened = elem;
	}
}
function hidemenu() {
	if(lastone_opened != '') {
		document.getElementById(lastone_opened).style.visibility = 'hidden';
	}
}