bug#6204: vc-dir always splits the frame

[Stefan Monnier]

>> Indeed.  A good way would be to provide a way to override pop-up-windows
>> (both nil and t) in special-display-regexps.  We already have
>> (same-window . t), so we only need to add the other half.
> In Juri's `switch-to-buffer-other-window' case such options would be
> useless anyway.

I was thinking of the OP's vc-dir case.

>> But maybe the user would like to follow the application's special
>> handling, even tho she modified her pop-up-windows for other reasons.
>> I think it's much better to use 2 separate variables, where the
>> user-controlled var is never modified by Elisp code.
> Applications that do care enough should either (1) use `split-window'
> and `set-window-buffer' or (2) provide a separate customizable option
> like `foo-pop-up-windows' and let the user decide whether this should
> pop up a new window and where.

If the buffer names are sufficiently regular and unique,
special-display-regexps can already provide the needed customizability
without any need for a new option.


        Stefan