It's always a pleasure to work on GWT: the code is quite clean and easy to read!
On a related note (to this patch), I was thinking about using CSS3 transitions for animations in widgets, when supported. The only issue is that there would only be an event fired at the end (ontransitionend). Is it really an issue to call child widget's onResize only once at the end of the animation, or should we "fake" the animation steps with a timer or requestAnimationFrame? (in which case maybe CSS transitions wouldn't be worth adding). -- http://groups.google.com/group/Google-Web-Toolkit-Contributors
