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
Page editing interface
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