Comment 2 for bug 1178767

I'd go with fixing the dodgy code in spritegroups rather than adding iterator access to GL3Slots, and I've fixed it in my private branch. It will be uploaded in the next revision.

However, one thing of note is that I'm looking at killing off SpriteGroups. Not sure if this will materialise or not, but it could do. The reason is that cameras simply do everything better than SpriteGroups, so it's very hard to justify keeping them.