Note: With a recently checked out Emacs 25.0.50 I can trigger both assertions as described below. Concerning Emacs 24.3.1 I can trigger only the first assertion but not the second one. Kind regards, Andreas 1) The first assertion is triggered by: * run emacs -Q -l pm-01.el * press "delete" twice And this is the backtrace: #0 0x00007ffff37d120b in raise (sig=6) at ../nptl/sysdeps/unix/sysv/linux/pt-raise.c:37 #1 0x000000000057f286 in terminate_due_to_signal (sig=6, backtrace_limit=2147483647) at emacs.c:386 #2 0x000000000060ca9d in die (msg=0x6f2768 "row >= 0 && row < matrix->nrows", file=0x6f2540 "dispnew.c", line=1405) at alloc.c:7108 #3 0x0000000000418d3e in matrix_row (matrix=0xf84b40, row=-1) at dispnew.c:1405 #4 0x0000000000479d85 in try_window_id (w=0x137c530) at xdisp.c:18436 #5 0x000000000046ee38 in redisplay_window (window=..., just_this_one_p=true) at xdisp.c:16396 #6 0x00000000004660e2 in redisplay_window_1 (window=...) at xdisp.c:14310 #7 0x000000000062cade in internal_condition_case_1 (bfun=0x4660a0 , arg=..., handlers=..., hfun=0x466024 ) at eval.c:1369 #8 0x000000000046529f in redisplay_internal () at xdisp.c:13953 #9 0x000000000046287a in redisplay () at xdisp.c:13158 #10 0x0000000000586ef8 in read_char (commandflag=1, map=..., prev_event=..., used_mouse_menu=0x7fffffffd865, end_time=0x0) at keyboard.c:2643 #11 0x0000000000596ced in read_key_sequence (keybuf=0x7fffffffda90, bufsize=30, prompt=..., dont_downcase_last=false, can_return_switch_frame=true, fix_current_buffer=true, prevent_redisplay=false) at keyboard.c:9257 #12 0x0000000000583e16 in command_loop_1 () at keyboard.c:1510 #13 0x000000000062c96d in internal_condition_case (bfun=0x583a3f , handlers=..., hfun=0x5831af ) at eval.c:1345 #14 0x00000000005836dd in command_loop_2 (ignore=...) at keyboard.c:1245 #15 0x000000000062bddb in internal_catch (tag=..., func=0x5836ba , arg=...) at eval.c:1106 #16 0x0000000000583691 in command_loop () at keyboard.c:1224 #17 0x0000000000582cdb in recursive_edit_1 () at keyboard.c:834 #18 0x0000000000582eab in Frecursive_edit () at keyboard.c:905 #19 0x0000000000580c10 in main (argc=4, argv=0x7fffffffde58) at emacs.c:1619 2) The second assertion is triggered by: * run emacs -Q -l pm-01.el * press "a" twice And this is the backtrace: #0 0x00007ffff37d120b in raise (sig=6) at ../nptl/sysdeps/unix/sysv/linux/pt-raise.c:37 #1 0x000000000057f286 in terminate_due_to_signal (sig=6, backtrace_limit=2147483647) at emacs.c:386 #2 0x000000000060ca9d in die (msg=0x6f92ee "row->enabled_p", file=0x6f6640 "xdisp.c", line=17524) at alloc.c:7108 #3 0x00000000004772c9 in find_last_row_displaying_text (matrix=0x15f57d0, it=0x7fffffff8690, start=0x1d8c720) at xdisp.c:17524 #4 0x0000000000479fce in try_window_id (w=0x137c530) at xdisp.c:18485 #5 0x000000000046ee38 in redisplay_window (window=..., just_this_one_p=true) at xdisp.c:16396 #6 0x00000000004660e2 in redisplay_window_1 (window=...) at xdisp.c:14310 #7 0x000000000062cade in internal_condition_case_1 (bfun=0x4660a0 , arg=..., handlers=..., hfun=0x466024 ) at eval.c:1369 #8 0x000000000046529f in redisplay_internal () at xdisp.c:13953 #9 0x000000000046287a in redisplay () at xdisp.c:13158 #10 0x0000000000586ef8 in read_char (commandflag=1, map=..., prev_event=..., used_mouse_menu=0x7fffffffd865, end_time=0x0) at keyboard.c:2643 #11 0x0000000000596ced in read_key_sequence (keybuf=0x7fffffffda90, bufsize=30, prompt=..., dont_downcase_last=false, can_return_switch_frame=true, fix_current_buffer=true, prevent_redisplay=false) at keyboard.c:9257 #12 0x0000000000583e16 in command_loop_1 () at keyboard.c:1510 #13 0x000000000062c96d in internal_condition_case (bfun=0x583a3f , handlers=..., hfun=0x5831af ) at eval.c:1345 #14 0x00000000005836dd in command_loop_2 (ignore=...) at keyboard.c:1245 #15 0x000000000062bddb in internal_catch (tag=..., func=0x5836ba , arg=...) at eval.c:1106 #16 0x0000000000583691 in command_loop () at keyboard.c:1224 #17 0x0000000000582cdb in recursive_edit_1 () at keyboard.c:834 #18 0x0000000000582eab in Frecursive_edit () at keyboard.c:905 #19 0x0000000000580c10 in main (argc=4, argv=0x7fffffffde58) at emacs.c:1619 In GNU Emacs 25.0.50.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.10.8) of 2015-01-04 on winky Repository revision: d7e858bcc6f353ea3e955ca2a91d7b5c33bb6611 Windowing system distributor `The X.Org Foundation', version 11.0.11501000 System Description: Ubuntu 14.04.1 LTS Configured using: `configure --prefix=/home/andreas/local/emacs --enable-checking=all --enable-check-lisp-object-type 'CFLAGS=-g3 -O0'' Configured features: XPM JPEG TIFF GIF PNG SOUND DBUS GSETTINGS NOTIFY GNUTLS LIBXML2 FREETYPE XFT ZLIB Important settings: value of $LC_COLLATE: en_US.UTF-8 value of $LC_CTYPE: en_US.UTF-8 value of $LC_MESSAGES: en_US.UTF-8 value of $LANG: en_US.UTF-8 value of $XMODIFIERS: @im=ibus locale-coding-system: utf-8-unix Major mode: Lisp Interaction Minor modes in effect: tooltip-mode: t global-eldoc-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 blink-cursor-mode: t auto-composition-mode: t auto-encryption-mode: t auto-compression-mode: t line-number-mode: t Recent messages: For information about GNU Emacs and the GNU system, type C-h C-a. Load-path shadows: None found. Features: (shadow sort gnus-util mail-extr emacsbug message dired format-spec rfc822 mml easymenu 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 time-date tooltip eldoc 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 elisp-mode 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 gfilenotify dynamic-setting system-font-setting font-render-setting move-toolbar gtk x-toolkit x multi-tty emacs) Memory information: ((conses 16 76943 4320) (symbols 48 18291 1) (miscs 40 45 125) (strings 32 11760 3895) (string-bytes 1 323298) (vectors 16 10065) (vector-slots 8 395354 9010) (floats 8 72 61) (intervals 56 192 0) (buffers 976 11) (heap 1024 44733 1424))