function scroll_gallery(direction) {
	photos = $('.photos div');
	shown = $('.photos div.shown').length;
	len = photos.length;
	ltail = 0;
	for(i=0;i < len && !$(photos[i]).hasClass('shown');i++) ltail++;
	rtail = len - ltail - shown;
	if(!ltail && !rtail) return;
	if(direction == 'right') {
		if(!rtail) return;
		$(photos[ltail]).removeClass('shown');
		$(photos[ltail+shown]).addClass('shown');
	} else if(direction == 'left') {
		if(!ltail) return;
		$(photos[ltail+shown-1]).removeClass('shown');
		$(photos[ltail-1]).addClass('shown');
	}
}