Old code (MooTools v1.2):
New code (MooTools v1.3):
This small change fixed all problems I had with dynamically loading data on my website (and it actually looks a bit better ;)). Hopefully it will be of use of you to, so you can also benefit of the new features that MooTools 1.3 has to offer!
I found one other change in behavior of Request.JSON(). In MooTools 1.2 you could request a page (or execute a command on your server) using Request.JSON() and return no data at all. With MooTools 1.3 the method will fail (calling the onFailure-method defined in the options) if you do not return a JSON-object (in my example I returned an empty string with the default server-headers). The fix for this is to use Request() instead since this method does not expect a JSON-object to be returned.