function PopupCentrata(width,height,file) {
   var w = width;
   var h = height;
   var l = Math.floor((screen.width-w)/2);
   var t = Math.floor((screen.height-h)/2);
      window.open(file,"finestra","width=" + w + ",height=" + h + ",top=" + t + ",left=" + l);
 }