I think it would be very helpful, especially to new users, if the online help index column scrolled independently of the main topic area so that the topic and sub-topics showed next to the main article. This is much easier to show than to describe so I’ll include pictures. It’s rather confusing as it currently stands until you figure out that you have to scroll to find the current topic on display and any sub -topics. If it scrolled you could easily see all the available topics and select them easily.
Help Site with Scrolling Index: