Scrollbars in FE are pretty small and have some quirks in behavior. I believe a few changes would help a bit.

Right now if you grab a scrollbar and scroll down, if you stray away from the bar area, the scrolling stops. If you move back to the bar area, the scrolling won't resume. Except on mouseDown event, which will snap the scrollbar to the area you currently point to.

It would be nice if the scrollbar didn't require such exact precision: scrolling up/down would work even if you stray from the exact area of the scrollbar. At the very least, getting the scrolling back on once the mouse comes back to the scrollbar area would help us old people with trembling hands.

For an example of what I'm talking about, just check ordinary browser scrollbars, stray left & right and see how they continue working, at least unless you enter another element with scrolling capabilities.