Publishing Code on Digital Platforms

I plan to write a new book next year (Effective C++11, about which I'll have more to say later, probably in January), and I'm laying the groundwork for it.  Part of that groundwork is doing what I can to ensure that the book looks good on all target platforms, by which I mean ink on paper as well as various digital representations (e.g., PDF, HTML, ePub, etc.)  I've noticed that many books containing code examples display, er, suboptimally on one or more digital devices, and I want to avoid that.  To that end, I've started a list of characteristics I think code displays should have, i.e., that readers should be able to take for granted in code displays.

A "code display" is code sitting in a paragraph on its own, i.e., like this:

// This code display consists of a class definition and a free function
class Widget {
public:
  explicit Widget();
  Widget(const Widget& rhs);
  Widget(Widget&& rhs);
  ...
};

std::ostream& operator<<(std::ostream& s, const Widget& w);

Here's my list so far:

• Code should be syntax-highlighted.
• Code should be copyable and pastable as text. This rules out using images for code displays.
• Code should be copyable and pastable as code. For example, if the code display has line numbers, there should be a way to copy and/or paste such that the line numbers are omitted.
• Code should be searchable. This also rules out using images for code displays.
• Viewing Code displays should not require horizontal scrolling.
• Code displays should have no bad line breaks.  This means no automatic wraparound due to the code not fitting in the available horizontal space.

There's a caveat to this "code reader's bill of rights." If you choose to view a code display in a "pathological" way, you lose the last two guarantees.  In general, this means that I expect you to have some reasonable horizontal width available on whatever device you're using.  If you view a code display on an iPhone in portrait mode, you're on your own.  If you view code on 10" tablet and set the font size to 200, you're on your own. If you view code on a giant PC screen and set the viewing window to 10 pixels wide, all bets are off.  As an author, I'm willing to do what I must to offer you these guarantees, and I'm willing to browbeat my publisher into offering them, too, but you have to give us a reasonable field to play on.

Are there other things you, as a reader, would like to be able to take for granted when viewing code displays in a technical publication?  Are there problems with code displays on digital devices that you've run into and that are not addressed above?  If so, let me know. Bear in mind that I'm trying to identify basic characteristics you should be able to take for granted, but currently cannot.  I'm happy to hear about nice-to-haves, too (e.g. it'd be nice to be able to click on or gesture over some code and have it automatically sent to an online site such as ideone or Live Work Space to be compiled and executed), but what I'm really interested in are things you should be able to take for granted.

Thanks,

Scott