imgIContainer should be split into two separate interfaces, one for decoders and libpr0n itself to use, and one for external users who just want to draw or get information about the current image. Bug 753 comment 48 has some specific suggestions as to what needs to be done.

one thing to note is that we should stop exposing StartAnimation here. All these consumers call it in OnStartContainer, which is stupid, because it's a no-op until >1 frames are available.

note - lockImage/unlockImage should probably be internal here, and we should require everyone to go through their imgIRequest to do locks/unlocks. Much less error prone I think.

This seems to be a duplicate of Bug 584841. Please re-open if this is not the case.