What I think the "issue" is is the fact that the way how the book is written is still the same as the signs, and you can't, and shouldn't, be able to edit much on a sign, since it has only four lines.
What I think would improve the writing a lot is if you could do things like: "Pressing Ctrl+A will select the whole page." or "Pressing Ctrl and the Left/Right Arrow will select everything the cursor passes though." because this happens with commands, and it's really handy.
Actually, no. I checked and in 14w05b this happens as well. I'll edit this once I see where it really origins from.