function toggleLayer( whichLayer )
  {
    var elem, vis;
    if( document.getElementById ) // this is the way the standards work
      elem = document.getElementById( whichLayer );
    else if( document.all ) // this is the way old msie versions work
        elem = document.all[whichLayer];
    else if( document.layers ) // this is the way nn4 works
      elem = document.layers[whichLayer];
    vis = elem.style;
    // if the style.display value is blank we try to figure it out here
    if(vis.display==''&&elem.offsetWidth!=undefined&&elem.offsetHeight!=undefined)
      vis.display = (elem.offsetWidth!=0&&elem.offsetHeight!=0)?'block':'none';
    vis.display = (vis.display==''||vis.display=='block')?'none':'block';
  }
  
  function showLayer( whichLayer )
  {
    var elem, vis;
    if( document.getElementById ) // this is the way the standards work
      elem = document.getElementById( whichLayer );
    else if( document.all ) // this is the way old msie versions work
        elem = document.all[whichLayer];
    else if( document.layers ) // this is the way nn4 works
      elem = document.layers[whichLayer];
    vis = elem.style;
    // if the style.display value is blank we try to figure it out here
    //if(vis.display==''&&elem.offsetWidth!=undefined&&elem.offsetHeight!=undefined)
      //vis.display = (elem.offsetWidth!=0&&elem.offsetHeight!=0)?'block':'none';
    vis.display = 'block';
  }
  
  function hideLayer( whichLayer )
  {
    var elem, vis;
    if( document.getElementById ) // this is the way the standards work
      elem = document.getElementById( whichLayer );
    else if( document.all ) // this is the way old msie versions work
        elem = document.all[whichLayer];
    else if( document.layers ) // this is the way nn4 works
      elem = document.layers[whichLayer];
    vis = elem.style;
    // if the style.display value is blank we try to figure it out here
    //if(vis.display==''&&elem.offsetWidth!=undefined&&elem.offsetHeight!=undefined)
      //vis.display = (elem.offsetWidth!=0&&elem.offsetHeight!=0)?'block':'none';
    vis.display = 'none';
  }