implement FlashSurface.clear()
minor
work on render targets and renderers
work on render targets and renderers
implement Node.getDescendants()
implement Node.getDescendantsByName()
nullify stack in iterative preorder
better split Node.getDescendantsByName() into two functions: getDescendantByName() and getAllDescendantsByName()
add SpriteGroup.getDescendantByName() and SpriteGroup.getAllDescendantsByName()
implement SpriteTools.computeLocalAxisAlignedBoundingBox()
return this in set() and setProduct()