2 - this is request by others as well. I will add an option to allow user choose display how many lines display. Or add a short outline at the beginning of text, for example, these text are leading with
` at beginning of content:
` # this is online heading
` This is some sub title, short description etc.
This part text only for outline, it won't render in HTML, PDF or any other format. Not sure if this is good idea, at least, another user is happy with this.
3 - A little surprise - I thought this is very straightforward function...
4 - I have thought fix typewriter scrolling line is fixed in middle of window, however, when I was implementing, I found it looks more flexible if user can change it. Maybe I can add some option to allow user fix or change this.
Marker of beginning of content is really a good point, I will add an indicator of this.