bug#70949: display-buffer-choose-some-window

[martin rudalics]

> The most reliable way to identify a series of related buffers
> is to set a buffer-local variable in the origin buffer
> to the window where outgoing buffers are displayed.

How would this work in the case of 'vc-dir'?  There you have a status
buffer whose buffer-local variable you probably want to set.  You call
'vc-diff' which calls 'vc-diff-internal' which eventually calls
'pop-to-buffer' which chooses the window of the outgoing buffer.  How
would you set up the variable in this scenario?

> Ideally, the users need to express their preference by a single alist entry.
> For example:
>
>    (use-previous-window . t) -- then all outgoing buffers will be displayed
>                                 in the same window
>
>    (use-mru-window . t) -- then all outgoing buffers will be displayed
>                            in the most recently used window
>                            instead of the default lru
>
> Or maybe a unified alist entry:
>
>    (prefer . previous-window)
>    (prefer . mru-window)

It's trivial to set up such an association for "*vc-diff*".  But what
would you do when calling 'vc-diff' with a different BUFFER argument?
Which kind of association would you set up for showing the next error
buffer in compilation output?

martin