function isVisible(node)
{
  for( var parent; parent = node.parentNode; node = parent )
    if (parent.style && parent.style.display == 'none')
      return false;
  return true;
}

function toggle(szID)
{
  var e = document.layers ? document.layers[szID] :
            document.getElementById ? document.getElementById(szID) :
              document.all[szID];
  var obj = e.style;
  var visible = document.layers ? (obj.display == 'hide') : (obj.display == 'none');
  obj.display = document.layers ? (visible ? 'show' : 'hide') : (visible ? '' : 'none');
  alt();
}

function alt()
{
  var fill = 0;
  var table = document.layers ? document.layers['listing'] :
                document.getElementById ? document.getElementById('listing') :
                   document.all['listing'];

  var rows = table.getElementsByTagName('a');

  if (rows == undefined || rows.length == 0)
	return;

  for(var i = 0; i < rows.length; i++)
  {
    if (!isVisible(rows[i]))
      continue;

    if(fill)
    {
      rows[i].className = 'b';
    } else {
      rows[i].className = 'w';
    }

    fill = !fill;
  }
}