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';}