Reported by jdahlin:

When resizing things, I think it's related to the main window of gazpacho I
sometimes get a crash. Backtrace attached in additional information. 

 bin/gazpacho:63: GtkWarning: file gtkwidget.c: line 2674
(gtk_widget_size_allocate): assertion `GTK_IS_WIDGET (widget)' failed
  gtk.main()

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -150505280 (LWP 8214)]
0x00e7f853 in gtk_combo_box_popdown () from /usr/lib/libgtk-x11-2.0.so.0
(gdb) bt
0 0x00e7f853 in gtk_combo_box_popdown () from /usr/lib/libgtk-x11-2.0.so.0
1 0x421ab1ee in g_cclosure_marshal_VOID__BOXED ()
   from /usr/lib/libgobject-2.0.so.0
2 0x421964f7 in g_cclosure_new_swap () from /usr/lib/libgobject-2.0.so.0
3 0x42196160 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
4 0x421a99be in g_signal_emit_by_name () from /usr/lib/libgobject-2.0.so.0
5 0x421a9157 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
6 0x421a9454 in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
7 0x01004c8f in gtk_widget_size_allocate () from /usr/lib/libgtk-x11-2.0.so.0
8 0x00f6b2e9 in gtk_table_get_homogeneous ()
   from /usr/lib/libgtk-x11-2.0.so.0
9 0x421ab1ee in g_cclosure_marshal_VOID__BOXED ()
   from /usr/lib/libgobject-2.0.so.0
10 0x421964f7 in g_cclosure_new_swap () from /usr/lib/libgobject-2.0.so.0
11 0x42196160 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
12 0x421a99be in g_signal_emit_by_name () from /usr/lib/libgobject-2.0.so.0
13 0x421a9157 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
14 0x421a9454 in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
15 0x01004c8f in gtk_widget_size_allocate () from /usr/lib/libgtk-x11-2.0.so.0
16 0x00ffca6e in gtk_vbox_new () from /usr/lib/libgtk-x11-2.0.so.0
17 0x421ab1ee in g_cclosure_marshal_VOID__BOXED ()
   from /usr/lib/libgobject-2.0.so.0
18 0x421964f7 in g_cclosure_new_swap () from /usr/lib/libgobject-2.0.so.0
19 0x42196160 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
20 0x421a99be in g_signal_emit_by_name () from /usr/lib/libgobject-2.0.so.0
21 0x421a9157 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
22 0x421a9454 in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
23 0x01004c8f in gtk_widget_size_allocate () from /usr/lib/libgtk-x11-2.0.so.0
0000024 0x00ffe428 in gtk_viewport_get_shadow_type ()
   from /usr/lib/libgtk-x11-2.0.so.0
0000025 0x421ab1ee in g_cclosure_marshal_VOID__BOXED ()
   from /usr/lib/libgobject-2.0.so.0
0000026 0x421964f7 in g_cclosure_new_swap () from /usr/lib/libgobject-2.0.so.0
0000027 0x42196160 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
0000028 0x421a99be in g_signal_emit_by_name () from /usr/lib/libgobject-2.0.so.0
0000029 0x421a9157 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
0000030 0x421a9454 in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
0000031 0x01004c8f in gtk_widget_size_allocate () from /usr/lib/libgtk-x11-2.0.so.0
32 0x00f49642 in gtk_scrolled_window_get_shadow_type ()
   from /usr/lib/libgtk-x11-2.0.so.0
0000033 0x421ab1ee in g_cclosure_marshal_VOID__BOXED ()
   from /usr/lib/libgobject-2.0.so.0
0000034 0x421964f7 in g_cclosure_new_swap () from /usr/lib/libgobject-2.0.so.0
0000035 0x42196160 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
0000036 0x421a99be in g_signal_emit_by_name () from /usr/lib/libgobject-2.0.so.0
0000037 0x421a9157 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
0000038 0x421a9454 in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
0000039 0x01004c8f in gtk_widget_size_allocate () from /usr/lib/libgtk-x11-2.0.so.0
0000040 0x00f1cef4 in gtk_notebook_new () from /usr/lib/libgtk-x11-2.0.so.0
0000041 0x421ab1ee in g_cclosure_marshal_VOID__BOXED ()
   from /usr/lib/libgobject-2.0.so.0
---Type <return> to continue, or q <return> to quit---
0000042 0x421964f7 in g_cclosure_new_swap () from /usr/lib/libgobject-2.0.so.0
0000043 0x42196160 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
44 0x421a99be in g_signal_emit_by_name () from /usr/lib/libgobject-2.0.so.0
45 0x421a9157 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
46 0x421a9454 in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
0000047 0x01004c8f in gtk_widget_size_allocate () from /usr/lib/libgtk-x11-2.0.so.0
0000048 0x00eadf29 in gtk_expander_get_type () from /usr/lib/libgtk-x11-2.0.so.0
0000049 0x421ab1ee in g_cclosure_marshal_VOID__BOXED ()
   from /usr/lib/libgobject-2.0.so.0
0000050 0x421964f7 in g_cclosure_new_swap () from /usr/lib/libgobject-2.0.so.0
0000051 0x42196160 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
0000052 0x421a99be in g_signal_emit_by_name () from /usr/lib/libgobject-2.0.so.0
53 0x421a9157 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
54 0x421a9454 in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
55 0x01004c8f in gtk_widget_size_allocate () from /usr/lib/libgtk-x11-2.0.so.0
56 0x00ffca6e in gtk_vbox_new () from /usr/lib/libgtk-x11-2.0.so.0
57 0x421ab1ee in g_cclosure_marshal_VOID__BOXED ()
   from /usr/lib/libgobject-2.0.so.0
58 0x421964f7 in g_cclosure_new_swap () from /usr/lib/libgobject-2.0.so.0
59 0x42196160 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
60 0x421a99be in g_signal_emit_by_name () from /usr/lib/libgobject-2.0.so.0
61 0x421a9157 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
62 0x421a9454 in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
63 0x01004c8f in gtk_widget_size_allocate () from /usr/lib/libgtk-x11-2.0.so.0
64 0x00ed51ec in gtk_hbox_new () from /usr/lib/libgtk-x11-2.0.so.0
65 0x421ab1ee in g_cclosure_marshal_VOID__BOXED ()
   from /usr/lib/libgobject-2.0.so.0
66 0x421964f7 in g_cclosure_new_swap () from /usr/lib/libgobject-2.0.so.0
67 0x42196160 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
68 0x421a99be in g_signal_emit_by_name () from /usr/lib/libgobject-2.0.so.0
69 0x421a9157 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
70 0x421a9454 in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
71 0x01004c8f in gtk_widget_size_allocate () from /usr/lib/libgtk-x11-2.0.so.0
72 0x00ffca6e in gtk_vbox_new () from /usr/lib/libgtk-x11-2.0.so.0
73 0x421ab1ee in g_cclosure_marshal_VOID__BOXED ()
   from /usr/lib/libgobject-2.0.so.0
74 0x421964f7 in g_cclosure_new_swap () from /usr/lib/libgobject-2.0.so.0
75 0x42196160 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
76 0x421a99be in g_signal_emit_by_name () from /usr/lib/libgobject-2.0.so.0
77 0x421a9157 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
0000078 0x421a9454 in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
0000079 0x01004c8f in gtk_widget_size_allocate () from /usr/lib/libgtk-x11-2.0.so.0
0000080 0x01014009 in gtk_window_reshow_with_initial_size ()
   from /usr/lib/libgtk-x11-2.0.so.0
0000081 0x421ab1ee in g_cclosure_marshal_VOID__BOXED ()
   from /usr/lib/libgobject-2.0.so.0
0000082 0x421964f7 in g_cclosure_new_swap () from /usr/lib/libgobject-2.0.so.0
0000083 0x42196160 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
84 0x421a99be in g_signal_emit_by_name () from /usr/lib/libgobject-2.0.so.0
85 0x421a9157 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
0000086 0x421a9454 in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
---Type <return> to continue, or q <return> to quit---
0000087 0x01004c8f in gtk_widget_size_allocate () from /usr/lib/libgtk-x11-2.0.so.0
0000088 0x0101588b in gtk_window_propagate_key_event ()
   from /usr/lib/libgtk-x11-2.0.so.0
0000089 0x421aa691 in g_cclosure_marshal_VOID__VOID ()
   from /usr/lib/libgobject-2.0.so.0
0000090 0x421964f7 in g_cclosure_new_swap () from /usr/lib/libgobject-2.0.so.0
0000091 0x42196160 in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
0000092 0x421a9bc5 in g_signal_emit_by_name () from /usr/lib/libgobject-2.0.so.0
0000093 0x421a9157 in g_signal_emit_valist () from /usr/lib/libgobject-2.0.so.0
0000094 0x421a9454 in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
0000095 0x00e87325 in gtk_container_check_resize ()
   from /usr/lib/libgtk-x11-2.0.so.0
0000096 0x00e870ef in gtk_container_set_reallocate_redraws ()
   from /usr/lib/libgtk-x11-2.0.so.0
0000097 0x075091f3 in g_child_watch_add () from /usr/lib/libglib-2.0.so.0
0000098 0x07505e4a in g_main_depth () from /usr/lib/libglib-2.0.so.0
99 0x07506f28 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
100 0x07507260 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
101 0x075078a3 in g_main_loop_run () from /usr/lib/libglib-2.0.so.0
102 0x00f05403 in gtk_main () from /usr/lib/libgtk-x11-2.0.so.0
0000103 0x006a6c16 in _wrap_gtk_main (self=0x0) at gtk.override:863
104 0x00187cb4 in eval_frame (f=0x831038c) at Python/ceval.c:3425
105 0x001890ae in PyEval_EvalCodeEx (co=0xf6ff34a0, globals=0xffffffff,
    locals=0x0, args=0x82e0164, argcount=1, kws=0x82e0168, kwcount=0,
    defs=0xf700ff58, defcount=1, closure=0x0) at Python/ceval.c:2663
0000106 0x00187c82 in eval_frame (f=0x82e0014) at Python/ceval.c:3528
107 0x001890ae in PyEval_EvalCodeEx (co=0xf6ff34e0, globals=0xffffffff,
    locals=0x0, args=0x0, argcount=0, kws=0x0, kwcount=0, defs=0x0,
    defcount=0, closure=0x0) at Python/ceval.c:2663
108 0x00189372 in PyEval_EvalCode (co=0x0, globals=0x0, locals=0x0)
    at Python/ceval.c:537
109 0x001a28b7 in run_node (n=0xf7037380,
    filename=0xffffffff <Address 0xffffffff out of bounds>, globals=0x0,
    locals=0x0, flags=0x0) at Python/pythonrun.c:1267
0000110 0x001a39e2 in PyRun_SimpleFileExFlags (fp=0x82de008,
    filename=0xfef9b87e "bin/gazpacho", closeit=1, flags=0xfef342a8)
    at Python/pythonrun.c:862
0000111 0x001a4a34 in PyRun_AnyFileExFlags (fp=0x82de008,
    filename=0xfef9b87e "bin/gazpacho", closeit=1, flags=0xfef342a8)
    at Python/pythonrun.c:659
0000112 0x001a972e in Py_Main (argc=1, argv=0xfef34374) at Modules/main.c:415
0000113 0x080485b2 in main (argc=0, argv=0x0) at Modules/python.c:23