(gdb) set env GDK_SYNCHRONIZE=1
(gdb) run
Starting program: /mnt/wd20ezrx-00dc0b0/JHBuild/3.20/install/bin/gnome-flashback 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffea07f700 (LWP 19403)]
[New Thread 0x7fffe987e700 (LWP 19404)]
[New Thread 0x7fffe8e79700 (LWP 19405)]
[New Thread 0x7fffdbfff700 (LWP 19406)]

(gnome-flashback:19399): Gdk-ERROR **: The program 'gnome-flashback' received an X Window System error.
This probably reflects a bug in the program.
The error was 'XSyncBadCounter'.
  (Details: serial 1610 error_code 134 request_code 134 (SYNC) minor_code 3)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the GDK_SYNCHRONIZE environment
   variable to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

Program received signal SIGTRAP, Trace/breakpoint trap.
_g_log_abort (breakpoint=1) at gmessages.c:327
327	}
(gdb) bt
#0  _g_log_abort (breakpoint=1) at gmessages.c:327
#1  0x00007ffff2bff15f in g_logv (log_domain=0x7ffff4637282 "Gdk", log_level=G_LOG_LEVEL_ERROR, format=0x7ffff4637a9d "%s", args=0x7fffffffca10) at gmessages.c:1079
#2  0x00007ffff2bff288 in g_log (log_domain=0x7ffff4637282 "Gdk", log_level=G_LOG_LEVEL_ERROR, format=0x7ffff4637a9d "%s") at gmessages.c:1118
#3  0x00007ffff45cab47 in _gdk_x11_display_error_event () from /mnt/wd20ezrx-00dc0b0/JHBuild/3.20/install/lib/libgdk-3.so.0
#4  0x00007ffff45da80e in gdk_x_error () from /mnt/wd20ezrx-00dc0b0/JHBuild/3.20/install/lib/libgdk-3.so.0
#5  0x00007ffff5393c4d in _XError () from /usr/lib/x86_64-linux-gnu/libX11.so.6
#6  0x00007ffff5390ad7 in ?? () from /usr/lib/x86_64-linux-gnu/libX11.so.6
#7  0x00007ffff5390b95 in ?? () from /usr/lib/x86_64-linux-gnu/libX11.so.6
#8  0x00007ffff5391b50 in _XReply () from /usr/lib/x86_64-linux-gnu/libX11.so.6
#9  0x00007ffff538d48d in XSync () from /usr/lib/x86_64-linux-gnu/libX11.so.6
#10 0x00007ffff538d52b in ?? () from /usr/lib/x86_64-linux-gnu/libX11.so.6
#11 0x00007ffff645e4c9 in XSyncSetCounter () from /usr/lib/x86_64-linux-gnu/libXext.so.6
#12 0x00007ffff45e469f in set_sync_counter () from /mnt/wd20ezrx-00dc0b0/JHBuild/3.20/install/lib/libgdk-3.so.0
#13 0x00007ffff45e47c0 in window_pre_damage () from /mnt/wd20ezrx-00dc0b0/JHBuild/3.20/install/lib/libgdk-3.so.0
#14 0x00007ffff45e47ee in on_surface_changed () from /mnt/wd20ezrx-00dc0b0/JHBuild/3.20/install/lib/libgdk-3.so.0
#15 0x00007ffff3a16db8 in ?? () from /usr/lib/x86_64-linux-gnu/libcairo.so.2
#16 0x00007ffff39be6b4 in ?? () from /usr/lib/x86_64-linux-gnu/libcairo.so.2
#17 0x00007ffff3a17396 in cairo_surface_set_mime_data () from /usr/lib/x86_64-linux-gnu/libcairo.so.2
#18 0x00007ffff45e48c2 in unhook_surface_changed () from /mnt/wd20ezrx-00dc0b0/JHBuild/3.20/install/lib/libgdk-3.so.0
#19 0x00007ffff45e788e in gdk_x11_window_destroy () from /mnt/wd20ezrx-00dc0b0/JHBuild/3.20/install/lib/libgdk-3.so.0
#20 0x00007ffff45a537d in _gdk_window_destroy_hierarchy () from /mnt/wd20ezrx-00dc0b0/JHBuild/3.20/install/lib/libgdk-3.so.0
#21 0x00007ffff45a547a in gdk_window_destroy () from /mnt/wd20ezrx-00dc0b0/JHBuild/3.20/install/lib/libgdk-3.so.0
#22 0x00007ffff4d4db03 in gtk_widget_real_unrealize () from /mnt/wd20ezrx-00dc0b0/JHBuild/3.20/install/lib/libgtk-3.so.0
#23 0x00007ffff4d6a32c in gtk_window_unrealize () from /mnt/wd20ezrx-00dc0b0/JHBuild/3.20/install/lib/libgtk-3.so.0
#24 0x00007ffff4d9e8d5 in gtk_plug_unrealize () from /mnt/wd20ezrx-00dc0b0/JHBuild/3.20/install/lib/libgtk-3.so.0
#25 0x00007ffff2f200ac in g_cclosure_marshal_VOID__VOIDv (closure=0x6f0f80, return_value=0x0, instance=0xab44a0, args=0x7fffffffd5a0, marshal_data=0x7ffff4d9e7cb <gtk_plug_unrealize>, n_params=0, 
    param_types=0x0) at gmarshal.c:905
#26 0x00007ffff2f1d558 in g_type_class_meta_marshalv (closure=0x6f0f80, return_value=0x0, instance=0xab44a0, args=0x7fffffffd5a0, marshal_data=0xd0, n_params=0, param_types=0x0) at gclosure.c:1024
#27 0x00007ffff2f1d0da in _g_closure_invoke_va (closure=0x6f0f80, return_value=0x0, instance=0xab44a0, args=0x7fffffffd5a0, n_params=0, param_types=0x0) at gclosure.c:867
#28 0x00007ffff2f399d8 in g_signal_emit_valist (instance=0xab44a0, signal_id=34, detail=0, var_args=0x7fffffffd5a0) at gsignal.c:3294
#29 0x00007ffff2f3abe7 in g_signal_emit (instance=0xab44a0, signal_id=34, detail=0) at gsignal.c:3441
#30 0x00007ffff4d3f600 in gtk_widget_unrealize () from /mnt/wd20ezrx-00dc0b0/JHBuild/3.20/install/lib/libgtk-3.so.0
#31 0x00007ffff494f414 in gtk_status_icon_set_visible () from /mnt/wd20ezrx-00dc0b0/JHBuild/3.20/install/lib/libgtk-3.so.0
#32 0x000000000044f167 in gf_power_applet_sync (applet=0x7fffd4002240) at gf-power-applet.c:261
#33 0x000000000044f274 in device_proxy_ready_cb (source_object=0xb2c210, res=0x9402b0, user_data=0x7fffd4002240) at gf-power-applet.c:303
#34 0x00007ffff320deb0 in g_task_return_now (task=0x9402b0) at gtask.c:1107
#35 0x00007ffff320dfcc in g_task_return (task=0x9402b0, type=G_TASK_RETURN_SUCCESS) at gtask.c:1165
#36 0x00007ffff320ead8 in g_task_return_boolean (task=0x9402b0, result=1) at gtask.c:1650
#37 0x00007ffff328dc8c in init_second_async_cb (source_object=0xb2c210, res=0x7fffd4002e00, user_data=0x9402b0) at gdbusproxy.c:1806
#38 0x00007ffff320deb0 in g_task_return_now (task=0x7fffd4002e00) at gtask.c:1107
#39 0x00007ffff320dfcc in g_task_return (task=0x7fffd4002e00, type=G_TASK_RETURN_SUCCESS) at gtask.c:1165
#40 0x00007ffff320e91e in g_task_return_pointer (task=0x7fffd4002e00, result=0xb6fe90, result_destroy=0x7ffff2c400cc <g_variant_unref>) at gtask.c:1544
#41 0x00007ffff328d257 in async_init_get_all_cb (connection=0x6fb210, res=0x940450, user_data=0x7fffd4002e00) at gdbusproxy.c:1443
#42 0x00007ffff320deb0 in g_task_return_now (task=0x940450) at gtask.c:1107
#43 0x00007ffff320dfcc in g_task_return (task=0x940450, type=G_TASK_RETURN_SUCCESS) at gtask.c:1165
#44 0x00007ffff320e91e in g_task_return_pointer (task=0x940450, result=0xb6fe90, result_destroy=0x7ffff2c400cc <g_variant_unref>) at gtask.c:1544
#45 0x00007ffff327d5a7 in g_dbus_connection_call_done (source=0x6fb210, result=0xb1c500, user_data=0x940450) at gdbusconnection.c:5704
#46 0x00007ffff320deb0 in g_task_return_now (task=0xb1c500) at gtask.c:1107
#47 0x00007ffff320df0d in complete_in_idle_cb (task=0xb1c500) at gtask.c:1121
#48 0x00007ffff2bf80b4 in g_idle_dispatch (source=0x7fffdc014a80, callback=0x7ffff320def5 <complete_in_idle_cb>, user_data=0xb1c500) at gmain.c:5441
#49 0x00007ffff2bf5585 in g_main_dispatch (context=0x6e7820) at gmain.c:3154
#50 0x00007ffff2bf6448 in g_main_context_dispatch (context=0x6e7820) at gmain.c:3769
---Type <return> to continue, or q <return> to quit---
#51 0x00007ffff2bf663b in g_main_context_iterate (context=0x6e7820, block=1, dispatch=1, self=0x721aa0) at gmain.c:3840
#52 0x00007ffff2bf6a75 in g_main_loop_run (loop=0x85aef0) at gmain.c:4034
#53 0x0000000000418fec in main (argc=1, argv=0x7fffffffdd18) at gf-main.c:159
