function mostrar(a)
        {
                document.getElementById(a).style.display="";
        }

        function esconder(a)
        {
                document.getElementById(a).style.display="none";
        }
		function alternar(obj) {
		var el = document.getElementById(obj);
		if ( el.style.display != 'none' ) {
		el.style.display = 'none';
		}
		else {
		el.style.display = '';
		}
		}

	function mudarimagem(img_name,img_src) {
document[img_name].src=img_src;
}