Re: comint read-only prompt

[Richard Stallman]

    > I don't feel very strongly about it, but I tend to agree with Noah on
    > this one: read-only properties are often annoying and should be used
    > *very* sparingly.

    Perhaps this should be told in the ELisp manual.

I think so.  But can we make the advice any more specific than just
"very sparingly"?

It seems to me that read-only properties are useful for creating a
structure within which there are editable fields.  For instance,
Custom, and the minibuffer, and maybe forms.el (if it uses them).

Are there any other types of situation where they are useful?