function popupCenter(pageURL) {
    var w = 3*screen.width / 4;
    var h = 3*screen.height / 4;
    var left = (screen.width/2)-(w/2);
    var top = (screen.height/2)-(h/2);
    var targetWin = window.open(pageURL, "_blank", 'scrollbars=yes,resizable=yes,menubar=no,toolbars=no,directories=no,location=no,status=no, width=' + w + ', height=' + h + ', top=' + top + ', left=' + left);
}