Clicking hyperlink to another chapter does not update chapter property
When the "next chapter" buttons are used in Gnome Books then the chapter number is set within libgepub, the content is updated, and a notify::chapter
signal is emitted.
When a link is followed within an ebook between chapters, the content is updated but the chapter number is not set and so no notify::chapter
signal is emitted. This means that the Gnome Books UI (and other users) aren't informed of internal navigation and can't update appropriately when it happens.
(Based on gnome-books#19)