Thanks for the suggestion.
I already tried to implement image caching in the reader, but it's not working well. Your code will be helpful.
However I'll try to keep the reader as simple as possible as it's the easiest way to achieve a maximum compatibility with different devices. And because I'm not a big fan of Javascript development. So I'm not sold yet on the swiping and the use of JQuery, we'll see...

Unfortunately there is no HTML file in Jar: all the HTML is generated at runtime directly by the code (there is no template).

I could "externalize" the javascript though. Let me know if this would be useful to you even without the ability to modify the HTML.

I think a simple option to add a regular expresion (some kind of "mask" to identify folders to ignore) could do the job.
For instance you could ignore all "#recycle" directories.

I think I understand why it happens.
Now I have to find a fix...

I understand how it would be useful for Kindle owners, but it won't happen for the following reasons:

1- It would require a lot of work for an operation which can be done (although not as easily) by downloading the book (usually a small file) and sending it by email with your usual email app or website.

2- This is a Kindle specific feature. I prefer to work on "generic" features that can be used by all devices. Moreover, Amazon hardware and file formats (azw, mobi) are closed and undocumented, working on them is painful.

Sorry.