how to control a TabGroupMorph ?

I would like to make a specific action when selecting a page of a tabGroupMorph. 

After looking a bit, I didn't find an easy way to do that. Usually, to control a morph, for example a DropListMorph, I use the class defining the dropList as Model, and therefore implement myself a #selectionIndex: method that does what I want to do.

For TabGroupMorph I have the impression that there is not the possibility to set such a model and deal with #setSelector #getSelector mechanism. Am I wrong?

The solution I use for now is to define my own subclass of TabGroupMorph to make my specific actions, which doesn't look very nice.

As you know much more than me, How would you do that ? I probably miss something, but if there is effectively no easy way to control a TabGroupMorph, wouldn't it be a good thing to implement such a mechanism?