// JavaScript Document
function popupCenter(url, name, width, height) {
    var left = (screen.availWidth - width) / 2;
    var top  = (screen.availHeight - height) / 2;
    var options = "left=" + left + ",top=" + top + 
       ",width=" + width + ",height=" + height;
    window.open(url, name, options);
}