[Haskell-cafe] HPC and derived instances

Hello! Why isn't there an option to control whether HPC, the Haskell Program Coverage, will consider derived instances "coverable". I'm using it and my top level coverage is 52% while my expression coverage is at 92%. Looking carefully we see that most non-tested top level definitions are derived Show, Eq and Ord instances that I always derive for most data types (as this is a library). I think it is nice that it recognizes class instances, but there should be a flag to ignore at least the derived ones. Am I missing something? Thanks! :) -- Felipe.