function open_close(topic_list,head_tag)
	{
		if( document.getElementById(topic_list).style.display == 'none' )
		{
			document.getElementById(topic_list).style.display = '';
			document.getElementById(head_tag).style.background = 'transparent url(/congress/images/open.gif) no-repeat';
		}
		else
		{
			document.getElementById(topic_list).style.display = 'none';
			document.getElementById(head_tag).style.background = 'transparent url(/congress/images/closed.gif) no-repeat';
		}
	}