Klaus and Craig --
Although I'd never posted before, I've been following these forums for nearly two years, which have helped me to solve a few problems. Thanks to all!
(BTW, I learned the basics of programming via Hypertalk ca. 1989, to which I switched to the superb, yet ill-fated Prograph IDE. LiveCode has been a godsend.)
I don't think that the bugs reported by Craig and by Klaus are relevant, inasmuch as the text fields in my PDF form include no borders.
As noted, at my end the app works fine in macOS 10.6.8, in the last version of 10.11.x, and in 10.12.4. Sans reports of PDF problems with LC 7.x and macOS 10.12.3, I'm at a loss.
Although the person who experienced the reported PDF problem had been provided a free copy of the app, she and other non-savvy computer users are not inclined to cooperate in trouble-shooting.
It's hard to find beta testers.
I'll just plunge ahead, assuming that my app will work under the most recent macOS with LiveCode 7.x.