Here's my pitch

You know how some websites have a little progress bar highlight across the top of the page to show how much of the page you've read?

Imagine a similar tool that shows you how much of the page is in view and how much remains, but persistently visible on every window on your computer, along the right side, integrated into a user interface tool that's wide enough that you can click on it, and not a moving target that disappears sometimes

I call it the "scroll bar"