// Define Behavior rules
var myrules = {
  'div#family_0' : function(el) {
    el.onmouseover = function() {
	  toggleBackground(el.id);
	  return false;
    },
	el.onmouseout = function() {
	  toggleBackground(el.id);
	  return false;
	}
  },
  'div#family_1' : function(el) {
    el.onmouseover = function() {
	  toggleBackground(el.id);
	  return false;
    },
	el.onmouseout = function() {
	  toggleBackground(el.id);
	  return false;
	}
  },
  'div#family_2' : function(el) {
    el.onmouseover = function() {
	  toggleBackground(el.id);
	  return false;
    },
	el.onmouseout = function() {
	  toggleBackground(el.id);
	  return false;
	}
  }
};
Behaviour.register(myrules);

function toggleBackground(id) {
	$(id).className = ($(id).className == id) ? id+'_over' : id;
}