This concept is called "outliner", see e.g. https://en.wikipedia.org/wiki/Ecco_Pro https://en.wikipedia.org/wiki/Ecco_Pro or https://github.com/rochus-keller/cr

This concept is called "outliner", see e.g. https://en.wikipedia.org/wiki/Ecco_Pro https://en.wikipedia.org/wiki/Ecco_Pro or https://github.com/rochus-keller/crossline/ https://github.com/rochus-keller/crossline/.