/* apertura popup */
function calc_left (w) {
   var left = (screen.availWidth / 2) - (w / 2);
   return (left);
}
function calc_top (h) {
   var top = (screen.availHeight / 2) - (h / 2);
   return (top);
}
function popup (url, id, w, h, scrollbars) {
   var top = calc_top (h);
   var left = calc_left (w);

   popupwindow = window.open(url, id, 'width='+w+',height='+h+',scrollbars='+scrollbars+',left='+left+',top='+top+',screenX='+left+',screenY='+top);
   popupwindow.focus();
}


/* popup segnala ad un amico */
function newsSegnala(url) {
   popup(url,'segnala_news_window',600,530,'no');
}