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.

More generally, we should not remove `widen' as a command, even if in only some
contexts. Likewise, `narrow'. What we should do is provide more user control
(not less), possibly by creating a `widen-one-level' command as I suggested
earlier.

As I suggested in the thread for bug #5839, one way to at least not encourage
user narrowing when that might get users (especially newbies) into trouble,
would be to inhibit the activation of the `Narrow' lighter in the mode line (the
lighter would still be shown but would not act as a widening button).