[KevinH]

FYI: Being able to emulate older (broken?) e-readers would simply be too hard to do. The bugs and omissions can be processor, model, and of course e-reader firmware specific.

The future of all reading apps (and according to google, most future apps of any kind on many platforms) is really browser engine based SDKs on both Desktops and of mobile devises.

The problem is the competing browser engines out there still leave open variation in e-readers.

Firefox/Mozilla has their own engine. On mobile, Apple forces the developer to use its Webkit based Safari engine (forces all browser and web apps to use it), and therefore, of course, Apple prohibits use of Chrome's WebEngine variant for mobile.

So no QtWebEngine based e-reader can be used for iOS. So Firefox, Opera, Chrome, etc on iOS is really being done on Webkit.

And it looks like future epub specs will be html, css, accessibility, json, and browser based if you look at what is being pushed out there as the epub next gen.

So I was less worried about legacy e-readers and more focused on more modern e-readers based on browser engines that can support javascript.

Perhaps there is no need for an opensource Desktop epub3 e-reader without a cloud interface and its associated tracking.

Perhaps just adding the ability for PageEdit in Preview mode to show the epub in a paginated fashion (one page or two page spreads), and a formatted Table of Contents extracted from the nav would be enough.