martin rudalics <rudalics@gmx....> writes:

>> My "interesting" result is that eventually the `foo' buffer ends being
>
> What does "eventually" mean?

This is the exact recipe:

emacs -Q

Start by evaluating this in *scratch*

(display-buffer
(get-buffer-create "foo")
'((use-side-window bottom 0) (pop-up-window-set-height . 1)))

Now do a C-h f <some-function-name> INTRO

The frame is splitted into two windows, one for *scratch* and another
for *Help*, "foo" is gone, C-x 1 does not work from *scratch*, C-x 1
from the *Help* buffer reports

byte-code: Cannot make side window the only window

>> displayed on a regular window covering half the screen with its usual
>> modeline. That window wont go away easily (C-x 1 while the other window
>> is active has no effect).
>
> That's part of the idea.  C-x 1 should not delete such windows and
> should not make such a window the only one on its frame.

It seems that Emacs reuses that window for displaying other buffers
(*Help*, in the recipe described above)