I'll take another look with that in mind.

macros.html might be difficult, though. I don't want to require users of the newsletter macro to add anything else to their template (because inevitably it'll be missed). But I haven't come up with a way to get the information about whether the macro was used and what form ID it ended up with out of the macro, so we could add the right code to a common js include or something and make it work right.