I would like to see two things that makes life easier
A navigation window on the left that lists the Headings and lets you jump quickly to another chapter, ideally the depth can be configured and this could be folded.
A feature to split the current screen to be able to enter text at two locations. Like in a cooking recipy where you have the ingredients a document start and the text below. Or in code where you have a section to define variables and below code. Or if you write meeting minutes and work on the minutes in the lower and on the participants in the upper window. Or when note taking in a web meeting you can see the participants in the upper window and take notes in the lower one. Alternatively you use open in a new window but this not so intuitive as you first have to look where the window is open which is distracting.