atari:xbios: Let SDL handles centering on screen.
atari:xbios: Keep non offseted value
atari:xbios: Properly setup pixels using offset.
atari:xbios: fixes centering also when surface is locked.
atari:timer: Throttles calls to BackgroundTask function, to avoid it being called too frequently.
atari:ikbd: Fix for Coldfire CPU. Contributed by Vincent Riviere.
atari:gem: Restore mouse on exit. Process mouse status after all events are processed.
atari:gem: Read application ID so we can use it.
atari:gem: Generate a fake message to mark regularly when to stop processing events.