Data.Array.MArray "lost" bounds

With ghc-6.6 there is a change in module Data.Array.MArray which now includes a function getBounds :: (MArray a e m, Ix i) => a i e -> m (i,i) but it misses the good old bounds [which had type bounds :: (HasBounds a, Ix i) => aie -> (i,i)]. What is the rational behind this change? Are MArrays now able to change there size? Thanks for any eplanations, Andreas