Making GWT custom widget

i want to make a GWT widget that looks like google+'s circle.

I checked on google's GWT website but they say that I have to look at the GWT source code (which is quite hard to understand for me)

I wonder if there exis开发者_StackOverflow中文版t any tutorial on making a custom GWT widget by using java?

Have you tried this :

http://code.google.com/webtoolkit/doc/latest/DevGuideUiCustomWidgets.html