var rules = {
	'.small-photo' : function(e) {
		e.onclick = function() {
			var main = $('main_photo');
			var alt = $("image_"+this.alt);
			main.src = alt.src;
			//main.width = alt.width;
			//main.height = alt.height;
		}
	}
}
Behaviour.register(rules);