In V 12.1, on windows, typing tutorial/VirtualBookOverview in the help windows shows this
Is it possible to obtain the earlier virtual book look, which is much nicer, since it is has expandable table to contents inline, so easier to view and navigate, as shown here by Jens (It seems new Virtual book was written using collection of notebooks, and hence missing table of contents (also called bookmarks in PDF files) which is very important for navigations of large documents). The first thing I do when I open a PDF file, is open the bookmarks view.
