base-3.0.3.0 not backwards compatible with base-3.0.2.0

Hi all, Could anyone confirm the following claims? * base-3.0.3.0 (shipped with GHC 6.10.1) is supposed to be backwards compatible with base-3.0.2.0 (shipped with GHC 6.8.3) ... * ... but it isn't! (For example, the Arrow class from Control.Arrow is a subclass of Category from Control.Category in base-3.0.3.0, but not in base-3.0.2.0.) Do we know of any similar issues? What's the recommended workaround when shipping code that is to support both GHC 6.8.* and GHC 6.10.*?) Thanks, Stefan