function popup(url, width, height, name, rtn)
{
    var open_args="toolbar=0,location=0,directories=0,status=0,scrollbars=0,menubar=0,resizable=0,width="+width+",height="+height;
    var win = window.open(url,name,open_args);
    win.moveTo((screen.availWidth-width)/2,(screen.availHeight-height)/2);
    win.focus();
    if (rtn) {
        return false;
    }
}