Subject: bug#11993: Emacs frames on other display hang during recursive edit on a different display

From: [email-masked]
Date: Wed, 18 Jul 2012 20:34:19 -0700

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and the GNU bug tracker at debbugs.gnu.org.  Please check that
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Please write in English if possible, as the Emacs maintainers
usually do not have translators for other languages.

Please describe exactly what actions triggered the bug, and
the precise symptoms of the bug.  If you can, give a recipe
starting from `emacs -Q':

    emacs -Q

        ...opens a frame (X Window)

        ...select that window, use it a bit to see that all works

        ESC-X make-frame-on-display

        ... type in display name
        ... note: in may case, the display is a different VNC session

        ... switch to the just opened emacs frame in that display, use it a
bit
        to see that all works

        ... switch back, again, just to see that all works.

        ... in eother of the frames, type

        ESC-X recursive-edit

        ...  I am still able to work in the frame that initiated the
recursive
        edit.

        ... However, in the other frames of the emacs, while I can select
the
        frame (X Window), and the cursor changes from outline to filled, I
        cannot do anything useful.  The other frame(s) are hung: typing is
not
        accepted, mouse clicks do not move the cursor.

        ... but the frame in which you typed recursive-edit still works

        ... switch back to that frame, type

        ESC-X exit-recursive-edit

        ... everything now works, in all frames.

    Further investigation shows that this hang occurs whenever the
    minibuffer is open in another frame.  I also find

        http://www.mail-archive.com/[email-masked]/msg08103.html

    to which Stallman responded:

        Re: Emacs hangs on current display when the minibuffer is
active on another
display
        Richard Stallman
        Wed, 27 Sep 2006 19:15:16 -0700

            If I leave the emacs on one
            display with the minibuffer active, emacs on the other display
does
            not respond to anything until the minibuffer input is resolved
(input
            entered, or quit).

        It is nearly impossible to fix this without making Emacs
        multi-threaded.  I hope that will be done some day, but I
        don't know if anyone is working on it.

    I suppose that I could give up and not report this bug.

    However, (a) reporting that this occurs with recursive-edit as well as
    minibuffer open may help the next person who encounters this bug, and
    (b) while I can imagine ways that the minibuffrer problem may be
    difficult to fix without multithreading (or good non-blocking
    asynchronous I/O), I must admit that I cannot imagine why recursive-edit
    would be like that.

    Also (c) I could swear that I *have* been able to use recursive-edit
    with multiple frames in the past, on older versions of emacs.  However,
I
    cannot reproduce this at the moment - all of the different versions of
    emacs I have access to have this problem.

    (By the way, my apologies for mailing this bug report from Microsoft
    Outlook or Gmail, although it was prepared in EMACS.)

If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
    `bt full' and `xbacktrace'.
For information about debugging Emacs, please read the file
/home/glew/import/emacs/emacs-24.1/install-dir-personal/share/emacs/24.1/etc/DEBUG.

In GNU Emacs 24.1.1 (x86_64-unknown-linux-gnu, GTK+ Version 2.10.4)
 of 2012-07-13 on mipscs587
Windowing system distributor `The XFree86 Project, Inc', version
11.0.40300000
Configured using:
 `configure '--with-gif=no'
 '--prefix=/home/glew/import/emacs/emacs-24.1/install-dir-personal''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: C
  value of $XMODIFIERS: nil
  locale-coding-system: nil
  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

Recent input:
<help-echo> <down-mouse-1> <mouse-1> <escape> x m a
k e - f r a m e <tab> - o n <tab> <return> l o c a
l h o s t L : 1 <backspace> <backspace> <backspace>
: 1 2 <return> <switch-frame> <help-echo> <down-mouse-1>
<mouse-1> <escape> x r e c u r s i v e - e d u <backspace>
i t <return> <down-mouse-1> <mouse-1> <escape> x e
x i t - r e c u r s i v e - e d i t <return> <switch-frame>
<down-mouse-1> <mouse-1> <down-mouse-1> <mouse-1> <down-mouse-1>
<mouse-1> q q q <down-mouse-1> <mouse-1> <backspace>
<backspace> <backspace> <escape> x r e p o r t - e
m a c s - b u g <return>

Recent messages:
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