Attached is a patch to add fischer-random castling support to eboard. It's a bit ugly**, but eboard can now reconstruct the position from a movelist which includes a castling correctly***. The legality check also works, but it remains impossible to signify short/long castling in the normal way in the GUI.
** There probably is a better way to initalize a parameter than I did with the replacement cpos when cg==NULL.
*** This can be verified by loading a PGN of fischer-random game, or by beginning the observation of a wild/fr game after a castling has occured.