Re: xref and displaying locations in appropriate window or frame

[Juri Linkov]

> I suppose there should be three modes but my understanding of this might
> be completely inadequate:
>
> - One that never displays the *xref* window but displays the next target
>   buffer via a command.  This is what etags did once IIRC.  I don't know
>   whether it's still around and has/had suitable navigational facilities
>   to return to the previous target buffer, for example.  Completion at
>   point works in a similar way if I'm not mistaken.
>
> - One that keeps the *xref* window open forever until the user deletes
>   it explicitly.  That's the variant we discuss here.  I think that this
>   variant should show the *xref* window at the bottom of the frame and
>   should show *xref* even if there is only one possible choice.
>
> - One that auto-hides the *xref* window as soon as the user makes a
>   choice.  That's the one proposed by xref.el and I believe it would
>   need an explicit command to redisplay the *xref* buffer instead of
>   asking the user to explicitly switch to it.  This variant should show
>   the *xref* buffer via ‘pop-to-buffer’ and probably replace it with the
>   target buffer whenever the user makes a choice.  It would immediately
>   show the target buffer when there's only one choice.  Completing via
>   the *Completions* window very much works according to this principle.

I think that once *xref* is displayed, it has to remain displayed
as long as the user continues the current navigation.

Whether to display *xref* initially should depend on the initial command, so
we could have two commands: one that displays *xref*, and another that doesn't
(i.e. your first and second options above).

In other respects, I see no reason for *xref* to operate differently from *grep*
and other similar existing next-error providers, so to display the *xref* window
using the default display action, and never auto-hide it.