I just tried to view an emacs window that had been idle for a long time. I don't remember if I was using Alt-Tab to cycle through the open windows or if I clicked on the emacs icon in the task bar. When I couldn't get to the window, I checked the terminal from which I had started emacs under gdb, and I saw that emacs had crashed: Program received signal SIGSEGV, Segmentation fault. 0x000000010068e6c9 in deselect_palette (f=0x0, hdc=0x0) at /usr/src/debug/emacs-24.3.94-1/src/w32xfns.c:123 123 if (f->output_data.w32->old_palette) (gdb) bt #0 0x000000010068e6c9 in deselect_palette (f=0x0, hdc=0x0) at /usr/src/debug/emacs-24.3.94-1/src/w32xfns.c:123 #1 0x000000010068e798 in release_frame_dc (f=0x0, hdc=0x0) at /usr/src/debug/emacs-24.3.94-1/src/w32xfns.c:154 #2 0x0000000100691df6 in uniscribe_encode_char (font=0x1010f5e98 , c=32) at /usr/src/debug/emacs-24.3.94-1/src/w32uniscribe.c:585 #3 0x000000010047dfe5 in get_glyph_face_and_encoding (f=0x1010f3c48 , glyph=0x60075a850, char2b=0x4280ce L"\003腐 B", two_byte_p=0x0) at /usr/src/debug/emacs-24.3.94-1/src/xdisp.c:24024 #4 0x000000010047f230 in x_get_glyph_overhangs (glyph=0x60075a850, f=0x1010f3c48 , left=0x428130, right=0x42812c) at /usr/src/debug/emacs-24.3.94-1/src/xdisp.c:24367 #5 0x000000010047f55b in left_overwriting (s=0x4281c0) at /usr/src/debug/emacs-24.3.94-1/src/xdisp.c:24446 #6 0x0000000100481200 in draw_glyphs (w=0x1010f4c48 , x=625, row=0x600790f20, area=TEXT_AREA, start=77, end=78, hl= DRAW_NORMAL_TEXT, overlaps=0) at /usr/src/debug/emacs-24.3.94-1/src/xdisp.c:24945 #7 0x0000000100489ed1 in x_write_glyphs (w=0x1010f4c48 , updated_row=0x600790f20, start=0x60075ae20, updated_area=TEXT_AREA, len=1) at /usr/src/debug/emacs-24.3.94-1/src/xdisp.c:26812 #8 0x000000010040a277 in update_text_area (w=0x1010f4c48 , updated_row=0x600790f20, vpos=23) at /usr/src/debug/emacs-24.3.94-1/src/dispnew.c:3746 #9 0x000000010040a64d in update_window_line (w=0x1010f4c48 , vpos=23, mouse_face_overwritten_p=0x42878f) at /usr/src/debug/emacs-24.3.94-1/src/dispnew.c:3848 #10 0x000000010040952b in update_window (w=0x1010f4c48 , force_p=true) at /usr/src/debug/emacs-24.3.94-1/src/dispnew.c:3427 #11 0x0000000100408c9a in update_window_tree (w=0x1010f4c48 , force_p=true) at /usr/src/debug/emacs-24.3.94-1/src/dispnew.c:3210 #12 0x0000000100408c63 in update_window_tree (w=0x600691538, force_p=true) at /usr/src/debug/emacs-24.3.94-1/src/dispnew.c:3208 #13 0x00000001004088b7 in update_frame (f=0x1010f3c48 , force_p=true, inhibit_hairy_id_p=false) at /usr/src/debug/emacs-24.3.94-1/src/dispnew.c:3099 #14 0x0000000100453e6c in redisplay_internal () at /usr/src/debug/emacs-24.3.94-1/src/xdisp.c:13967 #15 0x000000010045495f in redisplay_preserve_echo_area (from_where=8) at /usr/src/debug/emacs-24.3.94-1/src/xdisp.c:14185 #16 0x00000001005475cc in detect_input_pending_run_timers (do_display=true) at /usr/src/debug/emacs-24.3.94-1/src/keyboard.c:9897 #17 0x000000010063a6e7 in wait_reading_process_output (time_limit=0, nsecs=0, read_kbd=-1, do_display=true, wait_for_cell=4306509874, wait_proc=0x0, just_wait_proc=0) at /usr/src/debug/emacs-24.3.94-1/src/process.c:4699 #18 0x0000000100538e14 in kbd_buffer_get_event (kbp=0x429b88, used_mouse_menu=0x42a3cf, end_time=0x0) at /usr/src/debug/emacs-24.3.94-1/src/keyboard.c:3906 #19 0x0000000100533cf3 in read_event_from_main_queue (end_time=0x0, local_getcjmp=0x429fb0, used_mouse_menu=0x42a3cf) at /usr/src/debug/emacs-24.3.94-1/src/keyboard.c:2246 #20 0x0000000100534030 in read_decoded_event_from_main_queue (end_time=0x0, local_getcjmp=0x429fb0, prev_event=4306509874, used_mouse_menu=0x42a3cf) at /usr/src/debug/emacs-24.3.94-1/src/keyboard.c:2309 #21 0x0000000100535fe4 in read_char (commandflag=1, map=25780162614, prev_event=4306509874, used_mouse_menu=0x42a3cf, end_time=0x0) at /usr/src/debug/emacs-24.3.94-1/src/keyboard.c:2895 #22 0x00000001005455af in read_key_sequence (keybuf=0x42a5e0, bufsize=30, prompt=4306509874, dont_downcase_last=false, can_return_switch_frame=true, fix_current_buffer=true, prevent_redisplay=false) at /usr/src/debug/emacs-24.3.94-1/src/keyboard.c:9088 #23 0x0000000100531a04 in command_loop_1 () at /usr/src/debug/emacs-24.3.94-1/src/keyboard.c:1452 #24 0x00000001005dbdf0 in internal_condition_case (bfun=0x1005314ef , handlers=4306584322, hfun=0x100530a7a ) at /usr/src/debug/emacs-24.3.94-1/src/eval.c:1348 #25 0x00000001005310bd in command_loop_2 (ignore=4306509874) at /usr/src/debug/emacs-24.3.94-1/src/keyboard.c:1177 #26 0x00000001005db141 in internal_catch (tag=4306578482, func=0x10053108b , arg=4306509874) at /usr/src/debug/emacs-24.3.94-1/src/eval.c:1112 #27 0x000000010053104c in command_loop () at /usr/src/debug/emacs-24.3.94-1/src/keyboard.c:1156 #28 0x00000001005304db in recursive_edit_1 () at /usr/src/debug/emacs-24.3.94-1/src/keyboard.c:777 #29 0x000000010053070d in Frecursive_edit () at /usr/src/debug/emacs-24.3.94-1/src/keyboard.c:848 #30 0x000000010052e3e3 in main (argc=1, argv=0x42ab00) at /usr/src/debug/emacs-24.3.94-1/src/emacs.c:1647 Lisp Backtrace: "redisplay_internal (C function)" (0xaf7720) A full backtrace of all threads is attached. At the time of the crash, the emacs frame was split into two windows. One was viewing a plain text C++ file (ASCII only), and the other was a *grep* buffer from `M-x rgrep'. I have no idea how that strange (Chinese?) character got into frame 3. I still have the gdb session open. Ken In GNU Emacs 24.3.94.1 (x86_64-unknown-cygwin) of 2014-10-03 on desktop-new Windowing system distributor `Microsoft Corp.', version 6.1.7601 Configured using: `configure --srcdir=/home/kbrown/src/cygemacs/emacs-24.3.94-1.x86_64/src/emacs-24.3.94 --prefix=/usr --exec-prefix=/usr --bindir=/usr/bin --sbindir=/usr/sbin --libexecdir=/usr/libexec --datadir=/usr/share --localstatedir=/var --sysconfdir=/etc --libdir=/usr/lib --datarootdir=/usr/share --docdir=/usr/share/doc/emacs --htmldir=/usr/share/doc/emacs/html -C --with-w32 --with-file-notification=no --enable-checking=yes,glyphs 'CFLAGS=-ggdb -O2 -pipe -Wimplicit-function-declaration -O0 -g3 -fdebug-prefix-map=/home/kbrown/src/cygemacs/emacs-24.3.94-1.x86_64/build=/usr/src/debug/emacs-24.3.94-1 -fdebug-prefix-map=/home/kbrown/src/cygemacs/emacs-24.3.94-1.x86_64/src/emacs-24.3.94=/usr/src/debug/emacs-24.3.94-1' CPPFLAGS= LDFLAGS=-Wl,--stack,0x400000' Important settings: value of $LANG: en_US.UTF-8 locale-coding-system: utf-8-unix Major mode: Text Minor modes in effect: show-paren-mode: t display-time-mode: t delete-selection-mode: t tooltip-mode: t electric-indent-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 auto-composition-mode: t auto-encryption-mode: t auto-compression-mode: t temp-buffer-resize-mode: t buffer-read-only: t column-number-mode: t line-number-mode: t auto-fill-function: do-auto-fill transient-mark-mode: t view-mode: t Load-path shadows: None found. Features: (misearch multi-isearch mailalias mailclient browse-url qp help-mode pp shadow gnus-util mail-extr emacsbug message cl-macs 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 mail-prsvr mail-utils view server dired edmacro kmacro solar cal-dst planner-diary cl gv diary-lib diary-loaddefs planner-publish muse-xml planner advice help-fns cal-menu calendar cal-loaddefs sort muse-colors muse-latex muse-html muse-xml-common cus-edit muse-publish muse-project muse-protocols muse-regexps wid-edit cl-loaddefs cl-lib derived muse muse-nested-tags muse-mode gap-mode-autoloads info easymenu muse-autoloads package epg-config preview-latex tex-site auto-loads saveplace paren help-at-pt time delsel cus-start cus-load time-date tooltip electric uniquify ediff-hook vc-hooks lisp-float-type mwheel w32-common-fns disp-table w32-win w32-vars 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 dbusbind w32 multi-tty emacs)