the question is to know if you want to have abstract classes specifying 
coherent interface.
In general this is a good idea. And SLint detects this kind of problems.

>> I did find a valid one and reported it to mantis
>> #0000651. MorphicEvent>>cursorPoint refers to position
>> which is not defined for MorphicEvent (only in its
>> subclasses).
>
> Of course, we never have any instances of MorphicEvent, as it's an 
> abstract
> class.

stef