function openWindow(url, n, w, h, xpos, ypos) {
xpos = (screen.width-w)/2;
ypos = (screen.height-h)/2;
var windowprops = "width=" + w + ",height=" + h +",left=" + xpos +",top="+ ypos+",scrollbars='yes'";
var windowname = n;
popup = window.open(url,windowname,windowprops);
if(window.focus){
popup.focus();
}

}