var pop_window = '';
function open_window( url ) {
    if ( ! url ) {
         return false;
    }

    if (!pop_window.closed && pop_window.location) {
        pop_window.focus();
    } else {
        pop_window=window.open( url, '',
            'toolbar=0,location=0,directories=0,status=1,menubar=0,' +
            'scrollbars=yes,resizable=yes,' +
            'width=' + 620 + ',' +
            'height=' + 600 );
    }

    if ( ! pop_window.opener ) {
       pop_window.opener = window.window;
    }

    if ( window.focus ) {
        pop_window.focus();
    }

    return true;
}