(gdb) bt
#0  0x000000000043b539 in ghb_screen_par ()
#1  0x000000000043bc02 in ghb_par_scale ()
#2  0x000000000043ff54 in ghb_get_preview_image ()
#3  0x000000000043aa15 in ghb_set_preview_image ()
#4  0x000000000042370c in title_changed_cb ()
#5  0x00007f83ae37e10d in g_closure_invoke () from /usr/lib/libgobject-2.0.so.0
#6  0x00007f83ae39178c in ?? () from /usr/lib/libgobject-2.0.so.0
#7  0x00007f83ae392c3d in g_signal_emit_valist ()
   from /usr/lib/libgobject-2.0.so.0
#8  0x00007f83ae393133 in g_signal_emit () from /usr/lib/libgobject-2.0.so.0
#9  0x00007f83b19bab8a in ?? () from /usr/lib/libgtk-x11-2.0.so.0
#10 0x00007f83b19bc201 in gtk_combo_box_set_active_iter ()
   from /usr/lib/libgtk-x11-2.0.so.0
#11 0x0000000000430566 in ghb_ui_update ()
#12 0x000000000042534a in ghb_timer_cb ()
#13 0x00007f83ae0c873b in ?? () from /usr/lib/libglib-2.0.so.0
#14 0x00007f83ae0c7fd1 in g_main_context_dispatch ()
   from /usr/lib/libglib-2.0.so.0
#15 0x00007f83ae0cb6ad in ?? () from /usr/lib/libglib-2.0.so.0
#16 0x00007f83ae0cbbdd in g_main_loop_run () from /usr/lib/libglib-2.0.so.0
#17 0x00007f83b1a395e7 in gtk_main () from /usr/lib/libgtk-x11-2.0.so.0
#18 0x000000000042efae in main ()