I use Saki's state provider and this extension(great extenstion btw), they don't mash. Saki's state provider is an alternative to the cookie provider. SmartCheckBoxSelectionModel sets the provider to be cookies, stomping Saki's provider.

To resolve the issue I just removed the state provider settings (method onMouseDown, onHDMouseDown), not sure if you want to remove them ongoing, could be better just to check to see if a state provider is defined before setting it.