RE: Emacs's handling of line numbers [from bug#5042]

[Drew Adams]

> >> > For the same reason that the narrowing stack that Drew
> >> > proposes could be useful: if I'm reading an Info node, my
> >> > narrowing/widening shouldn't interfere with the use of narrowing
> >> > by Info-mode, because that's just an artifact of its
> >> > implementation. Being able to do M-x widen in an Info node
> >> > and seeing the whole buffer is IMO a "bug"
> >> > because it destroys the abstraction.
> >>
> >> I agree that user commands (with the prefix map `C-x n') should not
> >> widen or narrow the Info buffer outside of the current Info node.
> >> Only some low-level functions should be allowed to do this.
> >
> > That's going too far, IMO. As Eli will perhaps point out 
> > (see bug #5839), there are reasons that some users will
> > want to widen Info buffers.
> 
> I think Juri sugggested that there should not be an interactive
> command for doing that. Would not low level elisp functions be enough
> for the purpose of widening Info buffers?

(All commands are interactive.) Yes, I understood that that was Juri's
suggestion.

I disagree - `widen' should be a user command. And it should be available (but
not especially encouraged) in Info - see the reasons that Eli gave in the bug
#5839 thread as one example.

The proper way to tame widening is not to eliminate `widen' as a user command or
to restrict its use in a coarse, black-and-white way. The proper way is to:

1. Remove the button on the `Narrow' lighter in modes such as Info where we
don't want newbies to narrow without knowing what they're doing. (And perhaps
(_perhaps_), in such contexts, also ask for confirmation if the user invokes
`widen' in such a context. We already disable the command by default.)

2. Provide another command, `widen-one-level', which gives users more control
over the scope of widening. It would give them the same degree of control they
have now for narrowing. (No, this wouldn't prevent a user from widening to the
top level in Info, but it would give users more control generally.)