function wopen(url, name, w, h)
{
// Fudge factors for window decoration space.
 // In my tests these work well on all platforms & browsers.
w += 32;
h += 96;
 var win = window.open(url,
  name, 
  'width=' + w + ', height=' + h + ', ' +
  'location=no, menubar=no, ' +
  'status=no, toolbar=no, scrollbars=no, resizable=no');
 win.resizeTo(w, h);
 win.focus();
}
function set_cookie ( cookie_name, cookie_value,
    lifespan_in_days, valid_domain )
{
    var domain_string = valid_domain ?
                       ("; domain=" + valid_domain) : '' ;
    document.cookie = cookie_name +
                       "=" + encodeURIComponent( cookie_value ) +
                       "; max-age=" + 60 * 60 *
                       24 * lifespan_in_days +
                       "; path=/" + domain_string ;
}
function get_cookie ( cookie_name )
{
    var cookie_string = document.cookie ;
    if (cookie_string.length != 0) {
        var cookie_value = cookie_string.match (
                        '(^|;)[\s]*' +
                        cookie_name +
                        '=([^;]*)' );
        return decodeURIComponent ( cookie_value[2] ) ;
    }
    return '' ;
}