function getULMargin(el)  {
  var node = el.firstChild;
  var elHeight = 19;
  var totalHeight = elHeight;
  while (node != null) {
    totalHeight = totalHeight + elHeight;
    node = node.nextSibling;
  }
  if (totalHeight > elHeight) {
    elMargin = Math.round(totalHeight / 2)  ;
  } else  {
    elMargin = totalHeight;
  }
  return elMargin;
}

function displayULElement(el,status) {  
  var node = el.firstChild;
  while (node != null) {
    if (node.nodeName == 'UL') {    
      if (status) {
        document.getElementById("header").style.zIndex = '200';
        var marginTop = getULMargin(node);
        node.style.display = 'block';
        node.style.marginTop = '-'+marginTop+'px';
      } else  {
        document.getElementById("header").style.zIndex = '20';
        node.style.display = 'none';
      }  
      return false;
    }
    node = node.nextSibling;
  }
}