bug#25062: 24.5; Frame title (with "%b" format) changes when going to minibuffer

[Jonathan Marten <jjm@keelhaul.me.uk>]

When using the "%b" substitution in frame-title-format (the default
value includes this when there are multiple frames), the user would
expect the name of the buffer that they are editing to be shown.  This
happens, but when going to the minibuffer for any sort of prompt the
title changes to the buffer name of the minibuffer - "*Minibuf-0*" or
similar.  This may be what is happening internally, but it is an
implementation detail which does not need to be revealed.  The user
might wonder why the window title is changing just because they are
being prompted for some information.

Applying the following patch corrects this.  If the selected window is a 
minibuffer window, it evaluates the format string in the buffer of the 
minibuffer-selected-window instead of the buffer of the minibuffer.  With this 
patch, the frame title stays the same as before when being prompted in the 
minibuffer.

--- emacs-24.5/src/xdisp.c.orig	2015-04-02 08:23:06.000000000 +0100
+++ emacs-24.5/src/xdisp.c	2016-11-22 11:29:13.978385207 +0000
@@ -11612,6 +11612,7 @@
     {
       /* Do we have more than one visible frame on this X display?  */
       Lisp_Object tail, other_frame, fmt;
+      Lisp_Object this_window;
       ptrdiff_t title_start;
       char *title;
       ptrdiff_t len;
@@ -11640,9 +11641,17 @@
 			     format_mode_line_unwind_data
 			       (f, current_buffer, selected_window, 0));
 
-      Fselect_window (f->selected_window, Qt);
+      this_window = f->selected_window;
+      if ( MINI_WINDOW_P (XWINDOW (this_window)))
+        {
+          Lisp_Object original_window = Fminibuffer_selected_window ();
+          if (!NILP (original_window))
+            this_window = original_window;
+        }
+      Fselect_window (this_window, Qt);
+
       set_buffer_internal_1
-	(XBUFFER (XWINDOW (f->selected_window)->contents));
+	(XBUFFER (XWINDOW (this_window)->contents));
       fmt = FRAME_ICONIFIED_P (f) ? Vicon_title_format : Vframe_title_format;
 
       mode_line_target = MODE_LINE_TITLE;





In GNU Emacs 24.5.1 (x86_64-pc-linux-gnu, GTK+ Version 2.24.31)
 of 2016-11-22 on keelhaul
Windowing system distributor `The X.Org Foundation', version 11.0.11804000
Configured using:
 `configure --prefix=/usr --build=x86_64-pc-linux-gnu
 --host=x86_64-pc-linux-gnu --mandir=/usr/share/man
 --infodir=/usr/share/info --datadir=/usr/share --sysconfdir=/etc
 --localstatedir=/var/lib --disable-dependency-tracking
 --disable-silent-rules --docdir=/usr/share/doc/emacs-24.5-r3
 --htmldir=/usr/share/doc/emacs-24.5-r3/html --libdir=/usr/lib64
 --program-suffix=-emacs-24 --infodir=/usr/share/info/emacs-24
 --localstatedir=/var
 --enable-locallisppath=/etc/emacs:/usr/share/emacs/site-lisp
 --with-gameuser=:gamestat --without-compress-install
 --with-file-notification=inotify --enable-acl --without-dbus
 --without-gpm --without-hesiod --without-kerberos --without-kerberos5
 --with-xml2 --without-selinux --with-gnutls --without-wide-int
 --with-zlib --with-sound=alsa --with-x --without-ns --without-gconf
 --without-gsettings --with-toolkit-scroll-bars --with-gif --with-jpeg
 --with-png --with-rsvg --with-tiff --with-xpm --with-imagemagick
 --with-xft --without-libotf --without-m17n-flt --with-x-toolkit=gtk2
 GENTOO_PACKAGE=app-editors/emacs-24.5-r3 'CFLAGS=-O2 -march=native
 -pipe' CPPFLAGS= 'LDFLAGS=-Wl,-O1 -Wl,--as-needed''

Important settings:
  value of $EMACSLOADPATH: /usr/local/lib/xemacs/local:
  value of $LC_COLLATE: C
  value of $LC_MONETARY: en_GB.UTF-8
  value of $LC_TIME: C
  value of $LANG: en_GB.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  asi-indent-mode: 
  tooltip-mode: t
  mouse-wheel-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
  transient-mark-mode: t

Recent messages:
byte-code: End of buffer [2 times]
byte-code: Beginning of buffer [2 times]
Saving /home/jjm/.newsrc...
Saving file /home/jjm/.newsrc...
Wrote /home/jjm/.newsrc
Saving /home/jjm/.newsrc...done
Saving /home/jjm/.newsrc.eld...
Saving file /home/jjm/.newsrc.eld...
Wrote /home/jjm/.newsrc.eld
Saving /home/jjm/.newsrc.eld...done
End of buffer [2 times]

Load-path shadows:
/usr/local/lib/xemacs/local/site-start hides /etc/emacs/site-start

Features:
(shadow sort mail-extr warnings emacsbug sendmail gnus-topic utf-7
nndraft nnmh nnimap parse-time utf7 nnfolder gnus-agent gnus-srvr
gnus-score score-mode nnvirtual gnus-msg gnus-art mm-uu mml2015
epg-config mm-view mml-smime smime dig gnus-cache gnus-sum netrc gnutls
network-stream starttls tls nntp gnus-group gnus-undo nnmail mail-source
nnoo gnus-start gnus-spec gnus-int gnus-range message format-spec rfc822
mml mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231 rfc2047
rfc2045 ietf-drums mailabbrev gmm-utils mailheader gnus-win gnus
gnus-ems nnheader mail-utils wid-edit pp server sunkbd redo+ paren
browse-url paren-xe blink-paren buffer-frame frame-select
auto-set-indent sourcepair url url-proxy url-privacy url-expand
url-methods url-history url-cookie url-domsuf url-util url-parse
auth-source eieio byte-opt bytecomp byte-compile cl-extra cl-loaddefs
cl-lib cconv eieio-core gnus-util mm-util mail-prsvr password-cache
url-vars mailcap compile comint ansi-color ring sgml-mode psgml easymenu
datetrack edj site-gentoo gnu-compat advice help-fns time-date tooltip
electric uniquify ediff-hook vc-hooks lisp-float-type mwheel x-win x-dnd
tool-bar dnd fontset image regexp-opt fringe tabulated-list newcomment
lisp-mode prog-mode register page menu-bar rfn-eshadow timer select
scroll-bar 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
inotify dynamic-setting font-render-setting move-toolbar gtk x-toolkit x
multi-tty emacs)

Memory information:
((conses 16 173555 13977)
 (symbols 48 28250 0)
 (miscs 40 110 146)
 (strings 32 39827 6642)
 (string-bytes 1 1298501)
 (vectors 16 20550)
 (vector-slots 8 511832 8105)
 (floats 8 233 332)
 (intervals 56 295 0)
 (buffers 960 19)
 (heap 1024 40082 5871))