In the past, I have been using Dojo Toolkit for relatively little projects. I choose Dojo by its well designed API and its rich and homogeneous set of widgets.jQuery and jQueryUI are great projects, but I found the problem of consistency with jQuery plugins. Each one follow its own rules, each one has its documentation and API, etc.
Because of this, once I know Dojo I chose it as my preferred framework for RIA applications.
Here I would like to present you a short introduction on how to create widgets in Dojo. It is a simply summary of things relate to the widgets creation, it is not a step by step tutorial or code sample:
The presentation is built using the impress.js tool, so I recommend to visualize it using Chrome browser. You can use a recent version of FireFox too, but I see Chrome is the one which make smoothest visualization.