Option to have the BBDB window pop up by splitting the biggest window?

[N. Jackson]

Emacs version 27.0.50 (f3f67cf0b9a6388d423e048a7aafad2eb531b5a5)
GTK+ Version 3.22.26
BBDB version 3.2 from GNU Elpa

When reading news and mail in Gnus the arrangement of windows in the
frame is something like Fig. 1.

  +-------------------------------+
  |                               |
  |           Summary             |
  |                               |
  +-------------------------------+
  |                               |
  |                               |
  |                               |
  |           Article             |
  |                               |
  |                               |
  |                               |
  +-------------------------------+
  Fig. 1

When I use BBDB, it pops up it's buffer in a third window at the
bottom of the frame like this:

  +-------------------------------+
  |                               |
  |           Summary             |
  |                               |
  +-------------------------------+
  |                               |
  |                               |
  |           Article             |
  |                               |
  |                               |
  |-------------------------------|
  |            BBDB               |
  +-------------------------------+
  Fig. 2

This doesn't work well for me because my display is short and wide.
This default configuration reduces the precious vertical space in my
Article buffer, and also gives me a BBDB buffer that isn't really
tall enough to be useful.

When I set the BBDB variable `bbdb-mua-pop-up' to the value `horiz',
I get following layout:

  +-------------------------------+
  |                   |           |
  |      Summary      |   BBDB    |
  |                   |           |
  +-------------------------------+
  |                               |
  |                               |
  |                               |
  |            Article            |
  |                               |
  |                               |
  |                               |
  +-------------------------------+
  Fig. 3
  
But I would very much prefer to have

  +-------------------------------+
  |                               |
  |           Summary             |
  |                               |
  +-------------------------------+
  |                   |           |
  |                   |           |
  |                   |           |
  |      Article      |   BBDB    |
  |                   |           |
  |                   |           |
  |                   |           |
  +-------------------------------+
  Fig. 4
  
because the Summary buffer contains long lines here (191 characters
or more), so I don't want its window split; whereas the Article
buffer is typically filled at 80 or 76 or 72 characters so there is
lots of unused space at the right side of its window. Additionally
this window arrangement would provide a more generously-sized BBDB
buffer window.

Is there an option currently in BBDB to get the Fig. 4 layout? If
not, is there a possibility of one being added?

I notice that there is code in `bbdb-pop-up-window' so that the
"biggest" (actually tallest) window is split, but only in the case
of the so-called "vertical" split. Could (optional?) code be added
to the so-called "horizontal" split case so that it also looks for
the "biggest" window to split. Paradoxically, though, it would also
need to look for the tallest window to achieve Fig. 4.

What do you think?

N.