function toggleLayer( whichLayer )
{
 var layer, header, layervis, headervis;
 var headerid = whichLayer + 'header';
 var arrowid = whichLayer + 'arrow';
 if( document.getElementById ) { // this is the way the standards work
   layer = document.getElementById( whichLayer );
   header = document.getElementById( headerid );
   arrow = document.getElementById( arrowid );
 } else if( document.all ) { // this is the way old msie versions work
   layer = document.all[whichLayer];
   header = document.all[headerid];
   arrow = document.all[arrowid];
 } else if( document.layers ) { // this is the way nn4 works
   layer = document.layers[whichLayer];
   header = document.layers[headerid];
   arrow = document.layers[arrowid];
 }
 layervis = layer.style;
 headerimg = header.style;
		   
// if the style.display value is blank we try to figure it out here
 if(layervis.display=='' && layer.offsetWidth!=undefined && layer.offsetHeight!=undefined) {
   layervis.display = (layer.offsetWidth!=0 && layer.offsetHeight!=0)?'block':'none';
   var arrowimg = (layer.offsetWidth!=0 && layer.offsetHeight!=0)?'/images/arrow-rt.gif':'/images/arrow-dn.gif';
 }
 layervis.display = (layervis.display==''||layervis.display=='block')?'none':'block';
 var arrowimg = (layer.offsetWidth!=0 && layer.offsetHeight!=0)?'/images/arrow-dn.gif':'/images/arrow-rt.gif';
 
// headerimg.backgroundImage = (headerimg.backgroundImage==''||headerimg.backgroundImage=='url(/images/arrow-rt.gif)')?'url(/images/arrow-dn.gif)':'url(/images/arrow-rt.gif)';
 //var arrowimg = '/images/arrow-dn.gif';
// arrow.src = (arrow.src==''||arrow.src=='/images/arrow-rt.gif')?'/images/arrow-dn.gif':'/images/arrow-rt.gif';
document.images[arrowid].src = arrowimg;
}