function openWindow(width,height,url) {
    x = (640 - width)/2, y = (480 - height)/2;
	if (screen) {
        y = (screen.availHeight - height)/2;
        x = (screen.availWidth - width)/2;
    }
	window.open(url,'newWin','width='+width+',height='+height+',screenX='+x+',screenY='+y+',top='+y+',left='+x);
}