this is a common UIBinder Composite class. Notes:
1) for YUI, we are binding plain HTML Elements, like @UiField Element tabViewEl1;
2) then in the constructor, after this GWT widget is initialized with initWidget(uiBinder.createAndBindUi(this));, we call YUIBinder.bindYUI passing this Element UIFields corresponding to YUI stuff and register myself as a listener to be notified when YUI binding is done to start working.
3) in yuiBinded() callback we ask for YUI Widgets and start working with them.
@author sg