To date my main criticism of dojo is the documentation. I’m not going to go so far to say there isn’t any, but it is really lacking for someone that wants to do more than just the simple examples they have shown. The book of dojo is a nice run broad rundown of things while the most useful part of it is the examples you get when you download the scripts. On the dojo website they mention a few books out now, so I may jump on that.
It is also worth noting I have been trying to get this same functionality out of Microsoft’s ASP.net Ajax with minimal success. I have found using a .net update panel combined with the ASP.net ajax controls can be a significant headache if you want to extend the basic features even minimally. One would assume the onResize event invoked by a resize control would be able to trigger an update panel, think again.