Ah, the blessed relief!
A friend of mine wrote with this to say:
I spotted this on your blog. The good news is, Yes, you can turn it off. The bad news is, I’ve forgotten how. Let me know if you can’t find it (it’s a checkbox in some kind of options dialog box somewhere) and I’ll see if I can find out …
Well, after some effort I found the appropriate checkbox, and yes it does work, after a fashion anyway.
No more irritating dialogs to interrupt my flow.
But, no more automatic correction of my identifier capitalization either.
Pity - I was getting used to it as a kind of feedback that I hadn’t typed something incorrectly.
Oh well. Never mind.