bug#16909: 24.3; scrolling *Completions* window with tab sometimes chooses a wrong window

[martin rudalics]

> Yes, I just have (for the first time, my bug report was about 24.3).
> And 2 things:
>
> 1. I still get invalid buffer, Meaning:
> - (setq other-window-scroll-buffer "*Completions*")
> - C-M-v always scrolls Completions buffer as it should
> - kill the completions buffer
> - C-M-v -> "Invalid buffer'

I checked in another fix.  Try now with emacs -Q

(progn
  (with-current-buffer (get-buffer-create "*foo*")
    (dotimes (i 100)
      (insert "foo......\n\n....foo....\n\n......foo\n\n....foo...."))
    (goto-char (point-min)))
  (display-buffer "*foo*")
  (with-current-buffer (get-buffer-create "*bar*")
    (dotimes (i 100)
      (insert "bar......\n\n....bar....\n\n......bar\n\n....bar...."))
    (goto-char (point-min)))
  (set-window-buffer (split-window) "*bar*")
  (setq other-window-scroll-buffer (get-buffer "*foo*")))

and do C-M-v.  It should scroll *foo*'s window.  Next do

(kill-buffer "*foo*")

It should scroll *bar*'s window now.

> 2. But most interestingly, on the latest trunk I cannot reproduce my
> original issue anymore.
> Contrary to 24.3 TAB for auto-complete seems to work just fine. I'll
> investigate this more
> to make sure it really is as it should and will report my findings.
> If it's just a coincidence (my local work environment is playing tricks on
> me) I'll
> try to implement some fix this weekend.
>
> Were you ever able to reproduce this issue on trunk? If so, when?

Always.  On the attached screenshot you see the selected window at the
bottom right and the *Completions* window at the bottom left.  I can't
scroll the *Completions* window via C-M-v from the selected window.  So
I'm afraid you still have to look into this.

martin