1 There are other, equally valid, interpretations of the acronym RSS.
2 You must register with Yahoo! to obtain a developer’s ID to use the web service. If you don’t want to do that, the hosted version of the application reads from an XML file instead of accessing the on line web service.
3 You may already be familiar with Java’s JNI—the Java Native Interface. The GWT’s JSNI is a clever take, both in name and in deed, of the JNI.
4 UIObject is the superclass of Widget.
5 The Address Book application does not implement a true closure because the state of the callstack is not retained, but the effect is much the same as a true closure.