If you don't mind, I'd mark this bug as duplicate of (later filed) bug #1280665 which correctly attributes the bug to be in SDL 1.2 which enables backingstore wrongly in composited environment (if I understood correctly).
Please give out your test result there on the PPA version, and if I incorrectly marked this as duplicate please remove the duplicate status.
If you don't mind, I'd mark this bug as duplicate of (later filed) bug #1280665 which correctly attributes the bug to be in SDL 1.2 which enables backingstore wrongly in composited environment (if I understood correctly).
Please give out your test result there on the PPA version, and if I incorrectly marked this as duplicate please remove the duplicate status.