I want middle-click and drag to scroll

When I middle-click on a link, I’m happy that most of the time it opens a new tab.
What I want is that when I middle-click on open background or non-UI element, that the (FireFox and many other programs, like older Visual Studio) cursor turn into a scrolling cursor, and I can either scroll up and down, or in any direction. I think it was called smooth scrolling. I don’t care if it’s smooth-scrolling. I do want it to be like this: middle-click, scroll with mouse, middle-click-again exits the feature (stops scrolling and ends mode).