Hi, I'm seeing symptoms very similar to those in #12258, although I can't get the graphical dialog from `emacs -Q`. Running the following elisp causes a modal dialog to open that cannot be closed (none of 'yes', 'no' or the close window buttons do anything). When this happens, I also cannot interact with the main emacs frame: (let ((last-nonmenu-event nil) (use-dialog-box t)) (y-or-n-p "foo ")) Backtraces after getting running the above elisp (sorry I don't have gdb installed): (lldb) thread backtrace all * thread #1: tid = 0x76aa31, 0x00007fff9ad20a1a libsystem_kernel.dylib`mach_msg_trap + 10, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP * frame #0: 0x00007fff9ad20a1a libsystem_kernel.dylib`mach_msg_trap + 10 frame #1: 0x00007fff9ad1fd18 libsystem_kernel.dylib`mach_msg + 64 frame #2: 0x00007fff923a1fc5 CoreFoundation`__CFRunLoopServiceMachPort + 181 frame #3: 0x00007fff923a15e9 CoreFoundation`__CFRunLoopRun + 1161 frame #4: 0x00007fff923a0f25 CoreFoundation`CFRunLoopRunSpecific + 309 frame #5: 0x00007fff955faa0d HIToolbox`RunCurrentEventLoopInMode + 226 frame #6: 0x00007fff955fa7b7 HIToolbox`ReceiveNextEventCommon + 479 frame #7: 0x00007fff955fa5bc HIToolbox`_BlockUntilNextEventMatchingListInModeWithFilter + 65 frame #8: 0x00007fff8efb126e AppKit`_DPSNextEvent + 1434 frame #9: 0x00007fff8efb08bb AppKit`-[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 122 frame #10: 0x00007fff8f30fe2e AppKit`-[NSApplication _realDoModalLoop:peek:] + 642 frame #11: 0x00007fff8f30e54e AppKit`-[NSApplication runModalForWindow:] + 117 frame #12: 0x000000010017c840 Emacs`-[EmacsDialogPanel runDialogAt:] + 225 frame #13: 0x000000010017b60c Emacs`ns_popup_dialog + 707 frame #14: 0x00000001001064a0 Emacs`Ffuncall + 1037 frame #15: 0x000000010013876e Emacs`exec_byte_code + 2069 frame #16: 0x0000000100106ecc Emacs`funcall_lambda + 761 frame #17: 0x0000000100105cd5 Emacs`apply_lambda + 285 frame #18: 0x0000000100102f2f Emacs`eval_sub + 959 frame #19: 0x00000001001033de Emacs`Fprogn + 31 frame #20: 0x0000000100104283 Emacs`Flet + 635 frame #21: 0x0000000100102f56 Emacs`eval_sub + 998 frame #22: 0x0000000100105ba3 Emacs`Feval + 99 frame #23: 0x000000010010637b Emacs`Ffuncall + 744 frame #24: 0x000000010013876e Emacs`exec_byte_code + 2069 frame #25: 0x0000000100106ecc Emacs`funcall_lambda + 761 frame #26: 0x00000001001062e7 Emacs`Ffuncall + 596 frame #27: 0x000000010013876e Emacs`exec_byte_code + 2069 frame #28: 0x0000000100106ecc Emacs`funcall_lambda + 761 frame #29: 0x00000001001062e7 Emacs`Ffuncall + 596 frame #30: 0x0000000100101ca6 Emacs`Fcall_interactively + 4866 frame #31: 0x00000001001064a0 Emacs`Ffuncall + 1037 frame #32: 0x000000010010694b Emacs`call3 + 53 frame #33: 0x0000000100099e5f Emacs`command_loop_1 + 2813 frame #34: 0x0000000100104c8c Emacs`internal_condition_case + 282 frame #35: 0x00000001000a8e56 Emacs`command_loop_2 + 53 frame #36: 0x000000010010476c Emacs`internal_catch + 212 frame #37: 0x0000000100098b98 Emacs`recursive_edit_1 + 321 frame #38: 0x0000000100098cde Emacs`Frecursive_edit + 250 frame #39: 0x0000000100097ba6 Emacs`main + 4891 thread #3: tid = 0x76ab55, 0x00007fff9ad25662 libsystem_kernel.dylib`kevent64 + 10, queue = 'com.apple.libdispatch-manager' frame #0: 0x00007fff9ad25662 libsystem_kernel.dylib`kevent64 + 10 frame #1: 0x00007fff9a9ed421 libdispatch.dylib`_dispatch_mgr_invoke + 239 frame #2: 0x00007fff9a9ed136 libdispatch.dylib`_dispatch_mgr_thread + 52 thread #5: tid = 0x76ab57, 0x00007fff9ad24e6a libsystem_kernel.dylib`__workq_kernreturn + 10 frame #0: 0x00007fff9ad24e6a libsystem_kernel.dylib`__workq_kernreturn + 10 frame #1: 0x00007fff90548f08 libsystem_pthread.dylib`_pthread_wqthread + 330 thread #6: tid = 0x76ab58, 0x00007fff9ad24e6a libsystem_kernel.dylib`__workq_kernreturn + 10 frame #0: 0x00007fff9ad24e6a libsystem_kernel.dylib`__workq_kernreturn + 10 frame #1: 0x00007fff90548f08 libsystem_pthread.dylib`_pthread_wqthread + 330 thread #7: tid = 0x76ab59, 0x00007fff9ad249aa libsystem_kernel.dylib`__select + 10 frame #0: 0x00007fff9ad249aa libsystem_kernel.dylib`__select + 10 frame #1: 0x0000000100168a35 Emacs`-[EmacsApp fd_handler:] + 237 frame #2: 0x00007fff99bff76b Foundation`__NSThread__main__ + 1318 frame #3: 0x00007fff90547899 libsystem_pthread.dylib`_pthread_body + 138 frame #4: 0x00007fff9054772a libsystem_pthread.dylib`_pthread_start + 137 thread #8: tid = 0x76ab5a, 0x00007fff9ad24e6a libsystem_kernel.dylib`__workq_kernreturn + 10 frame #0: 0x00007fff9ad24e6a libsystem_kernel.dylib`__workq_kernreturn + 10 frame #1: 0x00007fff90548f08 libsystem_pthread.dylib`_pthread_wqthread + 330 thread #9: tid = 0x76ab5e, 0x00007fff9ad20a1a libsystem_kernel.dylib`mach_msg_trap + 10 frame #0: 0x00007fff9ad20a1a libsystem_kernel.dylib`mach_msg_trap + 10 frame #1: 0x00007fff9ad1fd18 libsystem_kernel.dylib`mach_msg + 64 frame #2: 0x00007fff923a1fc5 CoreFoundation`__CFRunLoopServiceMachPort + 181 frame #3: 0x00007fff923a15e9 CoreFoundation`__CFRunLoopRun + 1161 frame #4: 0x00007fff923a0f25 CoreFoundation`CFRunLoopRunSpecific + 309 frame #5: 0x00007fff8f15105e AppKit`_NSEventThread + 144 frame #6: 0x00007fff90547899 libsystem_pthread.dylib`_pthread_body + 138 frame #7: 0x00007fff9054772a libsystem_pthread.dylib`_pthread_start + 137 thread #10: tid = 0x76abc8, 0x00007fff9ad24e6a libsystem_kernel.dylib`__workq_kernreturn + 10 frame #0: 0x00007fff9ad24e6a libsystem_kernel.dylib`__workq_kernreturn + 10 frame #1: 0x00007fff90548f08 libsystem_pthread.dylib`_pthread_wqthread + 330 In GNU Emacs 24.3.1 (x86_64-apple-darwin13.1.0, NS apple-appkit-1265.19) of 2014-04-07 on zev-mbp.corp.dropbox.com Windowing system distributor `Apple', version 10.3.1265 Configured using: `configure '--prefix=/usr/local/Cellar/emacs/24.3' '--without-dbus' '--enable-locallisppath=/usr/local/share/emacs/site-lisp' '--infodir=/usr/local/Cellar/emacs/24.3/share/info/emacs' '--without-gnutls' '--with-ns' '--disable-ns-self-contained' 'CC=clang'' Important settings: value of $LANG: en_US.UTF-8 locale-coding-system: utf-8-unix default enable-multibyte-characters: t Major mode: Lisp Interaction Minor modes in effect: window-numbering-mode: t iswitchb-mode: t show-paren-mode: t 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 line-number-mode: t transient-mark-mode: t Recent input: M-x e m a c s C-a C-k r e p o r t Recent messages: For information about GNU Emacs and the GNU system, type M-h C-a. Making completion list... Load-path shadows: None found. 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 mail-prsvr mail-utils help-mode easymenu ack-and-a-half thingatpt grep compile comint ansi-color ring ack-and-a-half-autoloads package cc-styles cc-align cc-engine cc-vars cc-defs edmacro kmacro column-marker window-numbering uniquify advice help-fns cl-lib advice-preload pod-mode iswitchb paren time-date tooltip ediff-hook vc-hooks lisp-float-type mwheel ns-win tool-bar dnd fontset image regexp-opt fringe tabulated-list newcomment lisp-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 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 ns multi-tty emacs)