TextEditor scroll notification?

Is there a way to know when the user has scrolled down to the end of a TextEditor? We’d like to enable an Acknowledge button, but only after the user scrolls down to the bottom (on the assumption that means they actually read the text they are agreeing to). Similar to a License Agreement in an installer. I don’t see a listener callback that would do that. Perhaps I need to override a scroll method and issue my own callback?