When clicking in the scroll bar's track to move it, most implementations of a scroll bar move the scroll when the click begins and allow you to drag during the click.
Our current implementation uses the
widget.Clickable type, and that only emits "full" click events (press and release together). We'd need to essentially build our own raw pointer event handler.
This would also potentially be an opportunity to unify our Drag event handling and our click event handling into a single hit area, though I'm not 100% certain that is possible. Something to explore during implementation.