function openWindow(url, w, h) {
    var x=(document.layers)?(window.innerWidth-w)/2:(document.body.offsetWidth-w)/2
    var y=(document.layers)?(window.innerHeight-h)/2:(document.body.offsetHeight-h)/2;
    var t=(document.layers)?',screenX='+x+',screenY='+y : ',left='+x+',top='+y; // cross-browser code
    var x=window.open(url,'','scrollbars=yes,width='+w+',height='+h+',toolbar=yes,status=yes,menubar=yes,links=yes,resizable=yes'+t);
}