In the demo:
https://mbostock.github.io/stack/
scrolling down works fine, but once down a few pages, if then resizing (vigorously) the Safari window, scrolling messages seem to be sent.
Perhaps this is a result of the resizing of the scroll bar hitting some limits that send scroll messages. But I'm only guessing.
This does not happen on the first slide/page. You'll need to go down a few pages/slides before resizing to see this happen.