Wm notes 1.15.0

Pinging @mglukhovsky (and @larkost if he wants to check my checking on pull requests and issues).
This isn't actually easy to explain from the ticket, because part of the problem was that "OPAQUE" is a confusing term. (I was tempted to write "to make them more transparent" after "from error messages" but knew you'd call me on it.) I've added "when the data in the selection could not be printed"; if anyone has a better clarification I'm open to suggestions.