Language - the program interface.
The Contents group specifies the appearance of a book contents tree:
- Draw focused rectangle - a selected chapter will be placed in a rectangle.
- Full row selection - a whole line will be selected including the chapter ID.
- Horizontal lines - separates chapters with horizontal lines
- Vertical lines - separates a chapter ID from a title with a vertical line.
- Quick edit mode - clicking a chapter name makes it possible to edit it in this mode at once.