function popup(url,windowWidth,windowHeight){
if (windowWidth == null) { windowWidth = 664 }
if (windowHeight == null) { windowHeight = 503 }

var newWindow = null;
newWindow=window.open('','newWindow','width=' + windowWidth + ',height=' + windowHeight + ',status=no,toolbar=no,menubar=no,directories=no,location=no,scrollbars=no,resizable=no,alwaysRaised=yes,screenX=0,screenY=0,titlebar=no,z-lock=yes,left=' + (screen.width - windowWidth) / 2 + ',top=' + (screen.height - windowHeight) / 2);
if (newWindow != null) {
if (newWindow.opener == null){ newWindow.opener = self; }
newWindow.location.href=url;
newWindow.focus();
}
}