var index = "apresentacao";

function show( divshow ) {
	if ( index != divshow  ){
			divindex = document.getElementById( index );
			if ( divindex ) {
				divindex.style.display = "none";
			}
	}

	div = document.getElementById( divshow );
	if ( div ) {
		index = div.id;
		div.style.display = "block";
	}

    return false;
}