According to the documentation for kATEDocumentResourceChangedNotifier, it is supposed to be "Sent when ATE document resources, such as named style, have changed."

I have never found this to be true, in any version since the ATE was added. This has always been a serious pain point, because we build small previews of text styles and we have to rebuild them every time we open a UI that shows them, because we have no way of knowing if they have changed (or if they even still exist, or any have been added!).

Since it's never been sent before, there can't be much code expecting it -- so how much downside could there be to suddenly start sending them correctly?