// expand/hide toggle.
function toggleDiv(divId, linkId, showText, hideText) {
    var link    = document.getElementById(linkId);
    var oldText = link.innerHTML;
    var div     = document.getElementById(divId);
    
    if (oldText == showText) {
      div.style.visibility = 'visible';
      div.style.position   = 'static';
      link.innerHTML = hideText;
    } else {
      div.style.visibility = 'hidden';
      div.style.position   = 'absolute';
      link.innerHTML = showText;
    }
}