var last_description;

function showDescription(obj)
{
	if(document.getElementById(obj)==null) return false;
	hide_all_descriptions();
	if(document.getElementById(obj).style.display!='none') return false;
	document.getElementById(obj).style.display='block';
	last_description=obj;
	return true;
}

function hide_all_descriptions()
{
	var trs=document.getElementsByTagName('div');
	for(var i=0;i<trs.length;i++)
	{
		if(trs[i].getAttribute('class')!=null && trs[i].getAttribute('class')=='description')
			trs[i].style.display='none';
	}
}