The API doc pages are kind of a nuisance to navigate now, with two different scroll bars. It’s a nice idea to have the table-of-contents sidebar stay put, but the actually functionality is a mess. It was better without it.
Keyboard and mouse navigation are both a pain now, changing based on where your mouse cursor currently is, or where you last clicked…
Most of the time you can’t see the top, bottom, or the handle of the inner scroll bar, so you can’t tell where you are in the doc. When you hit one end of the inner frame then you start scrolling the outer one, which throws everything off.
Nested, scrolling frames are just a bad idea.