In JSF 1.1, there was no StageManagerWrapper provided by JSF so we were extending the base StateManager. In 1.2 this class was provided in order to support the delegation chain. This delegation chain is important to support the JSR-301's portlet bridge.
Trinidad's StateManagerImpl should be changed to extend JSF1.2's StateManagerWrapper class in order to support this delegation chain. The mechanism used in 1.1 is not sufficient for 1.2 extensions which may require a StateManager.