Manually add a line marker where text is paused

When I read a text without finishing it, I would like to add a line where I stopped. I know, that the scrollposition is saved, but on a tablet with small text size this can be a very large area. Would be great if one could put a line to the text with a double tap for example.

Start by locating the reader screen and the existing scroll-position save and restore behavior. Determine how a user gesture such as a double tap could place a visible marker at the current text line, then verify that the marker remains visible when returning to the unfinished text.

Written by the indexing model from the issue text.