function finestra (pagina,wi,he) {
var winl = (screen.width - wi) / 2;
var wint = (screen.height - he) / 3;
  win = window.open(pagina, "finestra",'resizable=yes,width='+wi+',height='+he+',outerheight='+he+',left='+winl+',top='+wint+',scrollbars=yes'); return false
}