I have been looking at this bug because I consider it a showstopper... I can get the crash now I run this code (progn ; (setq g (make-glyph (concat (locate-data-directory "time") "l-0.0.xpm"))) (setq g (make-glyph "doesnotexist.text")) (setq e (make-extent nil nil)) (setq global-mode-string (list (cons e g))) ; (set-extent-begin-glyph (make-extent 10 20) g) (redisplay-frame) (make-frame-on-tty nil) (hanoi 1) (garbage-collect)) No crash happens if the glyph is put on a normal extent instead of in the modeline. The crash is in compact_string_chars, hitting this assert string = from_s_chars->string; assert (!(LRECORD_FREE_P (string))); Now look it with a debugger... (gdb) print *from_s_chars $2 = {string = 0x2d2d2d2d, chars = "R"} (gdb) print from_s_chars->string $3 = (Lisp_String *) 0x2d2d2d2d (gdb) print *(from_s_chars->string) Cannot access memory at address 0x2d2d2d2d (gdb) print (char *)(from_s_chars->string) $4 = 0x2d2d2d2d <Address 0x2d2d2d2d out of bounds> (gdb) print (char *)&(from_s_chars->string) $5 = 0x8616fc8 "----Raw-----XEmacs: tok.el doesnotexist.text (Emacs-Lisp)----All", '-' <repeats 16 times>, "\n" ( i.e. The assert is going of because the from_s_chars structure has been overwritten by the text of the modeline... Jan