Currently, contract law do not dictate if it can be exchanged. E-books might or might not be transferable, and its currently up to the e-book seller to decide if that is the case. Property law, as far as e-books are property, do not come into effect unless e-book is made to be governed by property rules.
Could you explain how property law comes into effect in this case? If it does not, why could patents not be treated in the exact same and equal way.