EPUB: Previous/Next buttons should follow content.opf, not toc.ncx

[brjsp]

Some EPUB files have chapters which are not referenced by any anchor in toc.ncx. This causes missing/inaccessible content in kchmviewer.

[u-235]

Hi. Can you download such an ebook for the tests?

[brjsp]

https://libgen.li/ads.php?md5=6395F862507F37848EFAEDBB27968F7A

[u-235]

Thank you, it's clear what's going wrong.

Historically kchmviewer uses the table of contents for jumps using the "Next" and "Previous" buttons, most likely this is due to the lack of an official CHM specification. And there is no special code yet for navigating using the navigation map.

Conclusions:

• Add code for navigation map processing.
• Change the action of the "Home" button to show the title page instead of the first page in the table of contents.
• It would be useful to add an indication of the presence of hidden pages.

The goal is clear, but I don't have time to implement it yet.