> FWIW, there is a GDK_SYNCHRONIZE environment variable that makes GDK > call XSynchronize some places.
This the X error backtrace with GDK_SYNCHRONIZE set. Note this is not on Debian unstable and I couldn't install libX11 debug symbols. (gdb) bt #0 x_error (dpy=0x7ffff7e56460, error=0x7fffffffd560) at demo-Gtk.c:4257 #1 0x00007ffff6d03734 in _XError () at /lib/x86_64-linux-gnu/libX11.so.6 #2 0x00007ffff6d00107 in () at /lib/x86_64-linux-gnu/libX11.so.6 #3 0x00007ffff6d001a5 in () at /lib/x86_64-linux-gnu/libX11.so.6 #4 0x00007ffff6d0145d in _XReply () at /lib/x86_64-linux-gnu/libX11.so.6 #5 0x00007ffff6ceb54b in XInternAtom () at /lib/x86_64-linux-gnu/libX11.so.6 #6 0x00007ffff7ef76d4 in gdk_x11_atom_to_xatom_for_display (atom=0x9a, display=0x555555617020) at ../../../../../gdk/x11/gdkproperty-x11.c:115 #7 gdk_x11_atom_to_xatom_for_display (display=0x555555617020, atom=0x9a) at ../../../../../gdk/x11/gdkproperty-x11.c:96 #8 0x00007ffff7eeb65c in gdk_x11_display_translate_event (translator=<optimized out>, display=0x555555617020, event=0x5555559f2340, xevent=0x7fffffffd8e0) at ../../../../../gdk/x11/gdkdisplay-x11.c:1068 #9 0x00007ffff7ef1989 in _gdk_x11_event_translator_translate (translator=0x555555617020, display=0x555555617020, xevent=xevent@entry=0x7fffffffd8e0) at ../../../../../gdk/x11/gdkeventtranslator.c:51 #10 0x00007ffff7ef1474 in gdk_event_source_translate_event (xevent=0x7fffffffd8e0, event_source=0x555555629b40) at ../../../../../gdk/x11/gdkeventsource.c:243 #11 _gdk_x11_display_queue_events (display=0x555555617020) at ../../../../../gdk/x11/gdkeventsource.c:341 #12 0x00007ffff7eb90e4 in gdk_display_get_event (display=display@entry=0x555555617020) at ../../../../gdk/gdkdisplay.c:441 #13 0x00007ffff7ef10e6 in gdk_event_source_dispatch (source=<optimized out>, callback=<optimized out>, user_data=<optimized out>) at ../../../../../gdk/x11/gdkeventsource.c:363 #14 0x00007ffff718e17d in g_main_context_dispatch () at /lib/x86_64-linux-gnu/libglib-2.0.so.0 #15 0x00007ffff718e400 in () at /lib/x86_64-linux-gnu/libglib-2.0.so.0 #16 0x00007ffff718e4a3 in g_main_context_iteration () at /lib/x86_64-linux-gnu/libglib-2.0.so.0 #17 0x00007ffff7501fe5 in g_application_run () at /lib/x86_64-linux-gnu/libgio-2.0.so.0 #18 0x00005555555727e0 in main (argc=2, argv=0x7fffffffdcb8) at demo-Gtk.c:5365 (gdb)
