$ gdb gtk-window-decorator 
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Reading symbols from gtk-window-decorator...done.
(gdb) run
Starting program: /usr/bin/gtk-window-decorator 
warning: Could not load shared library symbols for linux-vdso.so.1.
Do you need "set solib-search-path" or "set sysroot"?
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/libthread_db.so.1".

** (gtk-window-decorator:5050): WARNING **: Couldn't register with accessibility bus: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.
[New Thread 0x7fffe8e4c700 (LWP 5054)]
[New Thread 0x7fffe3fff700 (LWP 5055)]

(gtk-window-decorator:5050): Pango-CRITICAL **: pango_font_description_from_string: assertion 'str != NULL' failed

(gtk-window-decorator:5050): Pango-CRITICAL **: pango_font_description_get_size: assertion 'desc != NULL' failed

(gtk-window-decorator:5050): Pango-CRITICAL **: pango_font_description_set_size: assertion 'desc != NULL' failed

(gtk-window-decorator:5050): Gtk-CRITICAL **: gtk_style_context_get_property: assertion 'priv->widget != NULL || priv->widget_path != NULL' failed

(gtk-window-decorator:5050): GLib-GObject-WARNING **: gtype.c:4221: type id '0' is invalid

(gtk-window-decorator:5050): GLib-GObject-WARNING **: can't peek value table for type '<invalid>' which is not currently referenced

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff6e09aa3 in gtk_style_context_get_valist () from /usr/lib/libgtk-3.so.0
(gdb) bt
#0  0x00007ffff6e09aa3 in gtk_style_context_get_valist () from /usr/lib/libgtk-3.so.0
#1  0x00007ffff6e09d63 in gtk_style_context_get () from /usr/lib/libgtk-3.so.0
#2  0x000000000041b8bb in frame_update_titlebar_font (frame=frame@entry=0x71ed00)
    at /home/korrode/builds/compiz-manjaro/compiz-manjaro-debug/src/compiz-0.9.12.0/gtk/window-decorator/decorator.c:157
#3  0x0000000000410ad3 in decor_frame_refresh (frame=0x71ed00)
    at /home/korrode/builds/compiz-manjaro/compiz-manjaro-debug/src/compiz-0.9.12.0/gtk/window-decorator/frames.c:91
#4  0x0000000000410c52 in gwd_get_decor_frame (frame_name=0x4222b9 "bare")
    at /home/korrode/builds/compiz-manjaro/compiz-manjaro-debug/src/compiz-0.9.12.0/gtk/window-decorator/frames.c:140
#5  0x000000000041cea8 in update_default_decorations (screen=0x6bc0d0)
    at /home/korrode/builds/compiz-manjaro/compiz-manjaro-debug/src/compiz-0.9.12.0/gtk/window-decorator/decorator.c:1335
#6  0x0000000000419c30 in decorations_changed (screen=0x6f8970)
    at /home/korrode/builds/compiz-manjaro/compiz-manjaro-debug/src/compiz-0.9.12.0/gtk/window-decorator/wnck.c:198
#7  0x000000000041e1fc in gwd_settings_notified_impl_update_decorations (notified=0x878c40)
    at /home/korrode/builds/compiz-manjaro/compiz-manjaro-debug/src/compiz-0.9.12.0/gtk/window-decorator/gwd-settings-notified.c:66
#8  0x00007ffff5b0fedd in g_list_foreach () from /usr/lib/libglib-2.0.so.0
#9  0x000000000041fb8a in release_notify_funcs (settings=<optimized out>)
    at /home/korrode/builds/compiz-manjaro/compiz-manjaro-debug/src/compiz-0.9.12.0/gtk/window-decorator/gwd-settings.c:147
#10 gwd_settings_thaw_updates (writable=<optimized out>)
    at /home/korrode/builds/compiz-manjaro/compiz-manjaro-debug/src/compiz-0.9.12.0/gtk/window-decorator/gwd-settings.c:548
#11 0x000000000040d987 in main (argc=1, argv=0x7fffffffe728)
    at /home/korrode/builds/compiz-manjaro/compiz-manjaro-debug/src/compiz-0.9.12.0/gtk/window-decorator/gtk-window-decorator.c:395