@Override
    protected void onUnload() {
        isFocused = false;
        super.onUnload();
    }
Called when the loading state changes. By default, this implementation
fires a {@link LoadingStateChangeEvent}.

@param state the new loading state
stroom-core-client-widget/src/main/java/com/google/gwt/user/cellview/client/AbstractHasData.java