When working on math it is very common to have a formula that you need to reference often. At the moment we always just have to either zoom out, or keep scrolling back to the section we wrote it in.

It would be great if we could do some kind of rectangular selection and have just that section of the page become a floating popup window (perhaps as a small square on the opposite side of our writing hand?) showing the contents that we selected, so that we dont have to keep awkwardly navigating through all the pages.

And maybe this extra feature is asking too much, but it would be amazing if for each notebook we could then have some kind of "index" of all the selections we made so that we could frequently switch what we show in our popup window.