Option 3 is what I did in Gobo as a temporary solution (we need to exclude two cursor classes as well).
I just checked, and our code at AXAR does not seem to use these two tree classes. So this is fine with me.

As for option 4, it cannot be worse to have a cursor class which inherits from a tree cursor class and a linked list cursor class than having linked tree class which inherits from a tree class and a linked list class.

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Eric Bezault