bug#6204: vc-dir always splits the frame

[Stefan Monnier]

>> No, the application's choice should prevail because it's more specific.
> I thought the idea was that an application can override a user's
> customizations iff it explicitly states that.

Yes and the users can still do that with special-display-regexps.
But pop-up-frames and pop-up-windows are really very vague global
preferences, whereas an application going through to trouble of
specifying default-params has decided that it usually deserves
special treatment.

> So should `pop-up-windows' be considered a "weaker" option than
> `special-display-regexps' wrt the argument of `display-buffer'?

Very much so, yes, since it's only a boolean value and applies to all
display-buffer calls, it's very non-discerning and carries very little
information about the user's preferences.

Some of the intention behind the `default-params' would be to get rid of
calls to switch-to-buffer (replaced by calls to pop-to-buffer with
a same-window default-param).  Such cases already disregard
pop-up-windows and pop-up-frames, so ignoring them w.r.t default-params
would be consistent with such a case.


        Stefan