The original commit of the PortletPreferencesBackingBean.java class was OK in that the action listener method signatures looked like the following:
... BUT a subsequent commit (that happened on the same day) removed the javax.faces.event.ActionEvent argument:
This caused a regression such that the "Save" and "Reset" buttons stopped working because Mojarra was unable to find the action listener methods on the beans.
NOTE: JSF 2.x has a feature such that action listeners do not require the javax.faces.event.ActionEvent argument.