- Scroll events are fired, but only if attached using addEventListener.
- nsIScrollbarListener sends callbacks but there is no consumer listening to them
- scrollbox is the only element that has a API to retrieve and adjust the scroll position, yet all elements may be scrollable.
- Add onscroll event for XUL elements. May be just a matter of adding to the list in nsXULElement::IsEventHandler
- Remove nsIScrollbarListener