Allow scrolling as is typical in desktop environments.

Currently scrollview scrolling with a mouse is not as good as with touch. This allows a scroll bar that is always present, and when clicking and dragging on the scroll bar, there is no time or distance minimum for it to scroll. It also scrolls down when you drag down instead of scrolling up as was the case. Finally, when the bar is dragged a full screen width, the scroll view child is also scrolled from top to bottom. This is all expected in desktop environments.

The only issue I can see, is that if enabled, the scroll bar will obscure whatever is underneath it. But I couldn't find a way to deal with this.