function open_url(url)
 {
 window.open(url);
 }

function toggle_extender(controlClass)
 {
 childElement = document.getElementById('extender-control');
 if (childElement.className == controlClass)
  {
  childElement.className = 'extended';
  }
 else
  {
  childElement.className = controlClass;
  }
 childElement = document.getElementById('extender');
 if (childElement.className == 'visible')
  {
  childElement.className = 'invisible';
  }
 else
  {
  childElement.className = 'visible';
  }
 }

function toggle_element(id)
 {
 collapsedElement = document.getElementById(id + '-collapsed');
 expandedElement = document.getElementById(id + '-expanded');
 if (collapsedElement.className == 'visible' && expandedElement.className == 'invisible')
  {
  collapsedElement.className = 'invisible';
  expandedElement.className = 'visible';
  }
 else
  {
  expandedElement.className = 'invisible';
  collapsedElement.className = 'visible';
  }
 }

function toggle_stage(id)
 {
 childElement = document.getElementById('stage_' + id).parentNode.getElementsByTagName('div');
 for (i = 0; i < childElement.length; i ++)
  {
  if (childElement[i].id.substring(0, 5) == 'stage')
   {
   if (childElement[i].id.substring(6) != id)
    {
    childElement[i].className = 'invisible';
    }
   else
    {
    childElement[i].className = 'visible';
    }
   }
  }
 }