public void onValueChange(ValueChangeEvent<String> event) {
// Find the SinkInfo associated with the history context. If one is
// found, show it (It may not be found, for example, when the user mis-
// types a URL, or on startup, when the first context will be "").
String token = event.getValue();
SinkInfo info = list.find(token);
if (info == null) {
showInfo();
return;
}
show(info, false);