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 her
  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';


}