function centerPopup (url, nome, w, h, scroll) {
    var winl = (screen.width - w) / 2;
    var wint = (screen.height - h) / 2;
    winprops = 'height='+h+',width='+w+',top='+wint+',left='+winl+',scrollbars='+scroll+',resizable, toolbars=false'
    win = window.open(url, nome, winprops)
    if (parseInt(navigator.appVersion) >= 4) { win.window.focus(); }
}