Maybe just link to examples on GitHub or on your website. You could also publish the entire book in HTML and host it behind a paywall on your own website. An interactive book sounds great!
It's nice to see these encouraging posts.

I'm still messing around with PDF settings. I might be able to make this work. If I do turn the book project into a Kickstarter project, I want to be sure that my idea actually works. I thought it did when I first started the project, but it seems that something might have changed.
But as for the Kickstarter idea, as a way to promote Stencyl, I saw this page...
http://www.stencyl.com/help/view/how-to-create-engine-extension/It seems that the Extension Ideas could be a good Kickstarter project.
- Dialog System
- Web Views
- Video
- Gamepads
- Push Notifications
- Data Structures (Dictionary, Trees)
- P2P Multiplayer / Networking
- Google Analytics
(I'm not a fan of Google Analytics... I like Piwik.)
Couldn't one... or all ...of these ideas be rolled into a Kickstarter project? I was thinking of making the book with Stencyl, using a Web View, which is how I stumbled on the Engine Extension page. I smiled when I saw the Multiplayer / Networking listing. It seems that there could be a demand for this kind of stuff.