function windowPopup(wUrl, wWidth, wHeight) {
    var xPos = (screen.availWidth  / 2) - (wWidth / 2);
    var yPos = (screen.availHeight / 2) - (wHeight / 2);
    window.open(wUrl, '', 'directories=no,location=no,menubar=no,resizable=yes,scrollbars=no,status=no,toolbar=no,width='+wWidth+',height='+wHeight+',left='+xPos+',top='+yPos);
}