bug#20206: 25.0.50; [PATCH] keep diff-mode's window visible when we visit sources from diff-mode

[martin rudalics]

>    (find-file "dat")
>    (find-file "dat.patch")        # open both files; one window/frame

You here ...

>    (split-window-horizontally)    # two windows; both show "dat.patch"
>    (other-window 1)               # switch to right window
>    (switch-to-buffer "asdf")      # switch to dummy "asdf" buffer
>    (other-window 1)               # left window active with "dat.patch",
>                                   # right shows "asdf"
>
>    (switch-to-buffer "dat")
>    (switch-to-buffer "dat.patch") # left window: show "dat" and then back
>                                   # to "dat.patch"

... and here tell Emacs that you very much like having dat and dat.patch
share the same window.  OTOH, the split-window-horizontally,
other-window, switch-to-buffer "asdf" sequence indicates that you rather
want the other window keep showing asdf.  So `display-buffer' will have
a hard time concluding here ...

>    (diff-goto-source))            # navigate to the diff source

... that you want to show dat in the window formerly occupied by asdf.

> In emacs23 the "dat" buffer is shown in the window OTHER than the one
> showing the diff. In emacs24, the diff window is covered up.

I see.  I don't yet have a solution for this.

martin