function mostra(lay) {
	if (document.layers) {
		document.uno.visibility='hidden'
		document.due.visibility='hidden'
		document.tre.visibility='hidden'
                document.quattro.visibility='hidden'
                document.cinque.visibility='hidden'
                if (lay != "canc") window.setTimeout("document."+lay+".visibility='visible'",50)
		}
	else {
		document.getElementById('uno').style.visibility = 'hidden'
		document.getElementById('due').style.visibility = 'hidden'
		document.getElementById('tre').style.visibility = 'hidden'
		document.getElementById('quattro').style.visibility = 'hidden'
		document.getElementById('cinque').style.visibility = 'hidden'
                if (lay != "canc") document.getElementById(lay).style.visibility='visible'
		}
}