Live mockup showing the draggable sections (source)
Mockup of the structure and metadata form, with draggable sections. Actions are stored within a dropdown menu. No support for nested sections.
Mockup that includes section headings
Mockup of edit form for a very long book. The zig-zag is not a part of the form; it's just to avoid actually adding 100 boxes in the mockup.
Live mockup (source)
Complete navigation bar
Simple navigation bar
Mockup of the editing interface with the option to choose a section from the left
Mockup of the editing interface with the option to choose a section from a dropdown above