Skins and behaviors should be able to add pseudo class states to the control. They already have the ability to override public PseudoClass.States getPseudoClassStates() { in SkinBase and BehaviorSkinBase classes. But that is useless without the ability to notify the control when a change to the state has occurred.

It is possible to allow SkinBase access by overriding the protected method in control there for granting package access. But that will not work for BehaviorSkinBase as that is in a different package. It seems that as getPseudoClassStates() is public it should be that pseudoClassStateChanged() should also be public