public StaticGroupShape(IList<Collidable> collidables, StaticGroup owner) { this.StaticGroup = owner; CollidableTree = new BoundingBoxTree<Collidable>(collidables); //Rather than hooking up a bunch of ShapeChanged events here that don't capture the full capacity of change //in our child collidables, we will rely on the user telling the collidable tree to reformat itself directly. }