// requires: non-null callback method or listener class // effects: adds the callback to the list of layer cbs public void AddLayerChangedCallback(LayerChangedCallback callback) { _layerChangeCbs.Add(callback); }
// requires: non-null callback method or listener class // effects: removes the callback from the list of layer cbs; noop if not found public void RemoveLayerChangedCallback(LayerChangedCallback callback) { _layerChangeCbs.Remove(callback); }