R: provide an outline in the editor

[jennybc]

I'm really missing the outline view that RStudio gives for R scripts. Today, for me, it happens to be about looking at test files, but I think it's a feature I miss in general.

https://posit.co/blog/rstudio-v1-4-preview-little-things/

[jmcphers]

We do have outlining implemented; if you like it alongside your script you can drag it from its default location in the Explorer bar over to the secondary sidebar.

Of course now you can't see the Session tab concurrently; AFAIK it isn't currently possible to dock a pane inside an editor so you can get an RStudio-like experience.

[jennybc]

OK let it be known this issue is now about the improving the ergonomics of the outline, i.e. making it feel more integrated with the editor. The issue specific to test files is #1428.

[kevinushey]

I feel like VSCode's answer to this in the minimap, e.g.

but honestly, I'm not a huge fan of that compared to the directly-accessible outline.

[jmcphers]

The minimap looks cool but it doesn't offer any sort of searchable or clickable navigation targets. It's really just a very thick and beautiful scroll bar. I know people like it (and I use it occasionally myself) but it definitely isn't a replacement for an outline.

[jennybc]

I am living in harmony with the OUTLINE these days, so #1428 covers my remaining wish, which is that the OUTLINE learns how to work with test files.

[IyarLin]

The VSCode outline does not support sections, sub sections etc in a way that makes it easy to navigate a long script like the Rstudio IDE does. Would really love having those sections/subsections including indentations like it's in the Rstudio