bug#12043: 24.1.50; NS: y-or-n-p-with-timeout with GUI hangs

[YAMAMOTO Mitsuharu]

Steps to reproduce:
  1. $ Emacs.app/Contents/MacOS/Emacs -Q
  2. (let (last-nonmenu-event) (y-or-n-p-with-timeout "foo" 3 'bar)) C-j
  3. Wait 3 seconds. 
  4. Repeat Step 2 and 3 if the dialog is popped down without hanging.

Result:
  It hangs within a few trials.
  Neither pushing buttons in the dialog nor C-g pops it down.

                                     YAMAMOTO Mitsuharu
                                mituharu@math.s.chiba-u.ac.jp

In GNU Emacs 24.1.50.1 (x86_64-apple-darwin11.4.0, NS apple-appkit-1138.47)
 of 2012-07-25 on yamamoto-no-iMac.local
Bzr revision: 109200 yamaoka@jpl.org-20120725032225-t89a214q5zgzlm5y
Windowing system distributor `Apple', version 10.3.1138
Configured using:
 `configure '--with-ns''

Important settings:
  value of $LANG: ja_JP.UTF-8
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t