function popup(url, name, height, width)
{
    var left = (screen.width - width) / 2;
    var top = (screen.height - height) / 2;
    var w = window.open(url, name, "scrollbars=no,resizable=no,toolbar=no,menubar=no,location=no,status=no," + "height=" + height + ",width=" + width + ",left=" + left + ",top=" + top);
    w.focus();
}