bug#7368: Testcase

[martin rudalics]

> C-h v pop-up-frames RET says:
>
> pop-up-frames's value is nil
>
> Documentation:
> Whether `display-buffer' should make a separate frame.
> If nil, never make a separate frame.
>
> However, a new frame *does* pop up for me after running the following code:
>
> (let ((foo (get-buffer-create "foo.el"))
>       (bar (get-buffer-create "bar.el")))
>   (switch-to-buffer foo)
>   (delete-other-windows)
>   (completion-at-point)
>   (display-buffer bar t))

On my trunk Emacs your code produces a new window on the selected frame.
Apparently, some of your settings prevent it from splitting the selected
window and the second argument t means `display-buffer' must not reuse
the selected window.  So `display-buffer' simply has no other choice but
making a new frame.

BTW, the snippet

(progn
  (delete-other-windows)
  (display-buffer (other-buffer) t))

should be sufficient for exhibiting the behavior you observe.

martin