Subject: bug#23450: 24.5; Lossing DECCKM application sequences on "fg"

From: Julien Palard <[email-masked]>
Date: Wed, 4 May 2016 18:18:14 +0200

Hi,

We noticed a bug, we're reproducing it like twice a week but we're still
unable to reproduce it explicitly, sorry for that.

Bug is: After sending emacs to the background with `C-z` and getting it
back with `fg`, sometimes, our terminal misses the
[DECCKM](http://www.vt100.net/docs/vt510-rm/DECCKM.html) flag.

We can easily fix it via `(send-string-to-terminal "\e[?1h")`, so we're
"sure" that this flag the "missing one", but we have no proof emacs is
faulty here.

It look like we're not alone:
http://stackoverflow.com/questions/4548106/screen-somehow-unmaps-my-arrow-keys-in-emacs-after-a-z/37032152

Here, we reproduced it with:

 - urxvt, putty, gnome term
 - emacs 24.5.1, emacs 24.4.1
 - GNU screen 4.02.01, 4.03.01, tmux 2.2
 - Debian GNU/Linux 8.4 (jessie)

Configured using:
 `configure --build x86_64-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/lib
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-pop=yes
 --enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.5/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.5/site-lisp:/usr/share/emacs/site-lisp
 --build x86_64-linux-gnu --prefix=/usr --sharedstatedir=/var/lib
 --libexecdir=/usr/lib --localstatedir=/var/lib
 --infodir=/usr/share/info --mandir=/usr/share/man --with-pop=yes
 --enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.5/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.5/site-lisp:/usr/share/emacs/site-lisp
 --with-x=no --without-gconf --without-gsettings 'CFLAGS=-g -O2
 -fstack-protector-strong -Wformat -Werror=format-security -Wall'
 CPPFLAGS=-D_FORTIFY_SOURCE=2 LDFLAGS=-Wl,-z,relro'

Important settings:
  value of $LC_ALL: en_US.utf8
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

     Minor modes in effect:
  global-company-mode: t
  company-mode: t
  global-flycheck-mode: t
  flycheck-mode: t
  icomplete-mode: t
  show-paren-mode: t
  tooltip-mode: t
  electric-indent-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
Quit
M-[ c is undefined [2 times]
M-[ d is undefined
M-[ c is undefined
Quit
call-interactively: Symbol's value as variable is void: Warning
M-[ d is undefined
M-[ c is undefined [2 times]
M-[ d is undefined
M-[ c is undefined

Load-path shadows:
/usr/share/emacs/24.5/site-lisp/debian-startup hides
/usr/share/emacs/site-lisp/debian-startup
/usr/share/emacs24/site-lisp/dictionaries-common/flyspell hides
/usr/share/emacs/24.5/lisp/textmodes/flyspell
/usr/share/emacs/site-lisp/rst hides
/usr/share/emacs/24.5/lisp/textmodes/rst
/usr/share/emacs24/site-lisp/dictionaries-common/ispell hides
/usr/share/emacs/24.5/lisp/textmodes/ispell

Features:
(shadow sort gnus-util mail-extr emacsbug message format-spec rfc822 mml
mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev
gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util
help-fns mail-prsvr mail-utils windmove mule-util xterm warnings
company-files company-oddmuse company-keywords company-gtags
company-dabbrev-code company-dabbrev company-capf company-cmake
company-ropemacs company-xcode company-clang company-semantic
company-eclim company-template company-css company-nxml company-bbdb
company-jedi jedi-core python-environment epc ctable concurrent deferred
company-etags etags ring company solarized-theme solarized-definitions
flycheck regexp-opt find-func help-mode rx subr-x seq dash icomplete
info tool-bar easymenu cl-macs package epg-config time-date paren
footnote edmacro kmacro cl gv cl-loaddefs cl-lib tooltip electric
uniquify ediff-hook vc-hooks lisp-float-type tabulated-list newcomment
lisp-mode prog-mode register page menu-bar rfn-eshadow timer select
mouse jit-lock font-lock syntax facemenu font-core frame cham georgian
utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
japanese hebrew greek romanian slovak czech european ethiopic indian
cyrillic chinese case-table epa-hook jka-cmpr-hook help simple abbrev
minibuffer nadvice loaddefs button faces cus-face macroexp files
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote make-network-process
dbusbind gfilenotify multi-tty emacs)

Memory information:
((conses 16 170938 7052)
 (symbols 48 24321 1)
 (miscs 40 47 144)
 (strings 32 34351 4678)
 (string-bytes 1 910734)
 (vectors 16 15367)
 (vector-slots 8 408448 2523)
 (floats 8 86 337)
 (intervals 56 250 123)
 (buffers 960 12)
 (heap 1024 23206 943))

-- 
Julien Palard
http://mdk.fr