#0  0x084d6227 in boost::detail::atomic_increment (pw=0x44656d65)
    at /usr/include/boost/detail/sp_counted_base_gcc_x86.hpp:66
#1  0x084d6240 in boost::detail::sp_counted_base::add_ref_copy (
    this=0x44656d61)
    at /usr/include/boost/detail/sp_counted_base_gcc_x86.hpp:133
#2  0x084d6268 in shared_count (this=0xbfbd8928, r=@0x9fe0fa4)
    at /usr/include/boost/detail/shared_count.hpp:216
#3  0x08597f34 in shared_ptr (this=0xbfbd8924)
    at /usr/include/boost/shared_ptr.hpp:131
#4  0x088ee3b4 in ARDOUR::StreamPanner::pan_control (this=0x9fe0f58)
    at libs/ardour/ardour/panner.h:76
#5  0xb7e9d620 in ARDOUR::Panner::automation_state (this=0x96dc908)
    at libs/ardour/panner.cc:934
#6  0x088e4a05 in PannerUI::update_pan_sensitive (this=0x9af94b4)
    at gtk2_ardour/panner_ui.cc:715
#7  0x088e812f in PannerUI::setup_pan (this=0x9af94b4)
    at gtk2_ardour/panner_ui.cc:433
#8  0x088e8619 in PannerUI::panner_changed (this=0x9af94b4)
    at gtk2_ardour/panner_ui.cc:334
#9  0x0888ba29 in sigc::bound_mem_functor0<void, PannerUI>::operator() (
    this=0x9b07cfc) at libs/sigc++2/sigc++/functors/mem_fun.h:1787
#10 0x0888ba40 in sigc::adaptor_functor<sigc::bound_mem_functor0<void, PannerUI> >::operator() (this=0x9b07cf8)
    at libs/sigc++2/sigc++/adaptors/adaptor_trait.h:251
#11 0x0888ba5c in sigc::internal::slot_call0<sigc::bound_mem_functor0<void, PannerUI>, void>::call_it (rep=0x9b07ce0)
    at libs/sigc++2/sigc++/functors/slot.h:103
#12 0x0850543a in sigc::internal::signal_emit0<void, sigc::nil>::emit (
    impl=0x9ac78a0) at libs/sigc++2/sigc++/signal.h:772
#13 0x08505502 in sigc::signal0<void, sigc::nil>::emit (this=0x96dc9b8)
    at libs/sigc++2/sigc++/signal.h:2667
#14 0x08505515 in sigc::signal0<void, sigc::nil>::operator() (this=0x96dc9b8)
    at libs/sigc++2/sigc++/signal.h:2675
#15 0xb7ea2f38 in ARDOUR::Panner::reset (this=0x96dc908, nouts=1, npans=2)
    at libs/ardour/panner.cc:884
#16 0xb7ea38d8 in ARDOUR::Panner::set_state (this=0x96dc908, node=@0x9c5f158)
    at libs/ardour/panner.cc:1093
#17 0xb7e4c235 in ARDOUR::IO::set_state (this=0x96dbfe0, node=@0x9c134e0)
    at libs/ardour/io.cc:1416
#18 0xb7ef6e43 in ARDOUR::Route::_set_state (this=0x96dbfe0, node=@0x9c5f040, 
    call_base=true) at libs/ardour/route.cc:2293
#19 0xb7d18701 in ARDOUR::AudioTrack::_set_state (this=0x96dbfe0, 
    node=@0x9c5f040, call_base=true) at libs/ardour/audio_track.cc:237
#20 0xb7d13a65 in ARDOUR::AudioTrack::set_state (this=0x96dbfe0, 
    node=@0x9c5f040) at libs/ardour/audio_track.cc:227
#21 0x08988b4a in MementoCommand<ARDOUR::Route>::undo (this=0x9c7ce68)
    at libs/pbd/pbd/memento_command.h:69
#22 0xb68207ed in UndoTransaction::undo (this=0x9c11188)
    at libs/pbd/undo.cc:137
#23 0xb6820e10 in UndoHistory::undo (this=0x96c6c88, n=0)
    at libs/pbd/undo.cc:254
#24 0x0871c0c6 in ARDOUR::Session::undo (this=0x96c6608, n=1)
    at libs/ardour/ardour/session.h:821
#25 0x08711b1b in Editor::undo (this=0x94a8fc8, n=1)
    at gtk2_ardour/editor_ops.cc:96