Boostnote: Support outlines/TOC in preview

[codito]

Scenario

An outliner (e.g. clickable list of headings in a doc) in preview mode can help navigate sections in a long document easily. I use boostnote for taking book notes. Currently editing a ~1500 lines doc with tens of chapters/sections, could save a bunch of keystrokes with this functionality available :)

Example

Here are a few example screenshots of similar idea in the wild.

1. VoOM outliner for VIM with markdown
   

2. Typora editor
   

[kazup01]

Hi @codito, thank you for your awesome suggestion! I also want it.
I made a mockup on a trial basis, what do you think about it?

[codito]

@kazup01 thanks for quick response. Mockup looks great!

Will the sidebar be optionally visible based on user action (may be a hotkey)? This way if anyone prefers a editor-only view (for distraction free writing), they can hide it. I like the idea of indenting sub headings, it looks neat.

[lpld]

This would be a great addition. For now, I can't find any way to navigate within a note, there is even no search in preview (or did i miss something?)

[Flexo013]

This will probably be fulfilled by this new feature from this issue: #3172

[Flexo013]

Duplicate of #2294 (which has funding)