bug#52053: 29.0.50; Nonsensical button "C-x C-f" in scratch buffer

[Gregory Heytings]

> Thanks, but I'd prefer a less obscure way of telling whether this is 
> going into *Help* buffers.  Is this really the only way?

I agree with you that it's a bit obscure, and I tried to find a better 
way, but couldn't.  Someone else might have a better idea.  I think 
another possible way would be to query this-command:

(in-help (or (eq major-mode 'help-mode)
             (and this-command
                  (where-is-internal this-command help-map t))))

But somehow I find this even less elegant, and I'm less certain about its 
correctness.

> Or maybe the mouse-face etc. should not be put as part of 
> substitute-command-keys, but by the Help mode itself, when the text is 
> already in the *Help* buffer?  As we use substitute-command-keys more 
> and more, these problems will probably pop up more and more, so maybe we 
> should rethink whether this part is really something it should do.

With this patch it shouldn't happen outside of Help mode anymore.