display-buffer-overriding-action

[Chong Yidong]

The new display-buffer design seems to work OK, but one aspect of it is
still bugging me: do we really need display-buffer-overriding-action?

If memory serves, the original idea was to allow the user to easily
impose options to override the ACTION argument to display-buffer,
applying to all buffers (unlike display-buffer-alist).  Such an option
might include the choice of window to reuse (currently not implemented).

But display-buffer-default-action should instead be used for such
purposes.  If we can assume that Lisp callers don't abuse the ACTION
argument for frivolous reasons, it is smarter to honor their specific
requests.  Such an override should not be necessary.