Add Persistent Vertical Document Navigation Column that Displays Headings #387
Description
The addition of a persistent vertical navigation column at the left or right of the HTML document, similar to those in Word and PDF documents, would be of great help, especially when navigating long documents. An extra bonus would be to include the ability to expand and collapse individual headings/subheadings within the navigation.
Not included in this issue, but something to think about: the ability to collapse headings/subheadings within the document itself.