When posing a character (e.g. sintel) in a scene file where the rig is linked from a library file, the proxy armature's 'rest position / pose position ' buttons are greyed out. In 2.49 it was possible to toggle them, useful sometimes for debugging issues and not wanting to see the animation (temporarily)

steps to reproduce:
1- link a character group
2- proxify (ctrl alt p) the control armature
3- observe the unclickable buttons..

not a major bug, but would be nice to have this back.
OS ubuntu 64 bit linux/ intel/ nvidia, but I don't think that's relevant here.