var lastCat='';

function getObject(ID,Silent){
	
	Silent=(typeof Silent=='undefined' ? false : Silent);
	
	var object;
	if(document.getElementById){object=document.getElementById(ID);}
	else if(document.all){object=document.all[ID];}
	else if(document.layers){object=document.layers[ID];}
	else{
		if(!Silent){
			alert('Cannot access object: '+ID);
		}
		return null;
	}
	if(object==null){
		if(!Silent){
			alert('Object not found: '+ID);
		}
	}
	return object;
}

function showCat(catID){
	  var newcat = getObject(catID,true);
	  if (newcat == null){
		  return;
	  }
	
	if(lastCat!=''){
		var opencat = getObject(lastCat,true);
		if (opencat != null){
			opencat.style.display='none';
		}
	}
	
	if(lastCat==catID){
		lastCat='';
	}
	else{
			newcat.style.display='block';	
			lastCat=catID;
	}
}