diff --git a/gtk2_ardour/tracks_control_panel.logic.cc b/gtk2_ardour/tracks_control_panel.logic.cc
index bd69f854f8..73993a4596 100644
--- a/gtk2_ardour/tracks_control_panel.logic.cc
+++ b/gtk2_ardour/tracks_control_panel.logic.cc
@@ -85,6 +85,7 @@ TracksControlPanel::init ()
 	EngineStateController::instance ()->EngineHalted.connect (stopped_connection, MISSING_INVALIDATOR, boost::bind (&TracksControlPanel::engine_stopped, this), gui_context());
 
 	/* Subscribe for udpates from EngineStateController */
+    EngineStateController::instance()->PortRegistrationChanged.connect (update_connections, MISSING_INVALIDATOR, boost::bind (&TracksControlPanel::on_port_registration_update, this), gui_context());
 	EngineStateController::instance()->BufferSizeChanged.connect (update_connections, MISSING_INVALIDATOR, boost::bind (&TracksControlPanel::on_buffer_size_update, this), gui_context());
     EngineStateController::instance()->DeviceListChanged.connect (update_connections, MISSING_INVALIDATOR, boost::bind (&TracksControlPanel::on_device_list_update, this, _1), gui_context());
     EngineStateController::instance()->InputConfigChanged.connect (update_connections, MISSING_INVALIDATOR, boost::bind (&TracksControlPanel::on_input_configuration_changed, this), gui_context());
@@ -568,9 +569,6 @@ TracksControlPanel::sample_rate_changed()
 void
 TracksControlPanel::engine_running ()
 {
-    populate_input_channels();
-    populate_output_channels();
-
 	_buffer_size_combo.set_active_text (bufsize_as_string (EngineStateController::instance()->get_current_buffer_size() ) );
 
 	_sample_rate_combo.set_active_text (rate_as_string (EngineStateController::instance()->get_current_sample_rate() ) );
@@ -744,6 +742,13 @@ void TracksControlPanel::on_midi_playback_active_changed(DeviceConnectionControl
 }
 
 
+void TracksControlPanel::on_port_registration_update()
+{
+    populate_input_channels();
+    populate_output_channels();
+}
+
+
 void
 TracksControlPanel::on_buffer_size_update ()
 {
diff --git a/gtk2_ardour/tracks_control_panel.logic.h b/gtk2_ardour/tracks_control_panel.logic.h
index 6d9ad03c2b..fca04f9a0d 100644
--- a/gtk2_ardour/tracks_control_panel.logic.h
+++ b/gtk2_ardour/tracks_control_panel.logic.h
@@ -107,6 +107,7 @@
     void populate_default_session_path();
 
     // Engine State update callback handlers
+    void on_port_registration_update();
     void on_buffer_size_update ();
     void on_device_list_update (bool current_device_disconnected);
     void on_parameter_changed (const std::string& parameter_name);
diff --git a/libs/ardour/ardour/engine_state_controller.h b/libs/ardour/ardour/engine_state_controller.h
index 79ac9e5481..aad51e852d 100644
--- a/libs/ardour/ardour/engine_state_controller.h
+++ b/libs/ardour/ardour/engine_state_controller.h
@@ -127,6 +127,9 @@ public:
     PBD::Signal0<void> InputConfigChanged;
     PBD::Signal0<void> OutputConfigChanged;
     
+    /* this signal is emitted if new ports are registered or unregistered */
+    PBD::Signal0<void> PortRegistrationChanged;
+    
 private:
 
     EngineStateController(); // singleton
@@ -210,6 +213,7 @@ private:
     void _on_buffer_size_change(ARDOUR::pframes_t);
     void _on_device_list_change();
     void _on_parameter_changed (const std::string&);
+    void _on_ports_registration_update ();
     ////////////////////////////////////////
         
     ////////////////////////////////////////
diff --git a/libs/ardour/engine_state_controller.cc b/libs/ardour/engine_state_controller.cc
index c6bcc9d1bc..288c009070 100644
--- a/libs/ardour/engine_state_controller.cc
+++ b/libs/ardour/engine_state_controller.cc
@@ -57,6 +57,7 @@ EngineStateController::EngineStateController()
 	AudioEngine::instance ()->Halted.connect_same_thread (stopped_connection, boost::bind (&EngineStateController::_on_engine_stopped, this) );
     
 	/* Subscribe for udpates from AudioEngine */
+    AudioEngine::instance ()->PortRegisteredOrUnregistered.connect_same_thread (update_connections, boost::bind (&EngineStateController::_on_ports_registration_update, this) );
     AudioEngine::instance()->SampleRateChanged.connect_same_thread (update_connections, boost::bind (&EngineStateController::_on_sample_rate_change, this, _1) );
 	AudioEngine::instance()->BufferSizeChanged.connect_same_thread (update_connections, boost::bind (&EngineStateController::_on_buffer_size_change, this, _1) );
     AudioEngine::instance()->DeviceListChanged.connect_same_thread (update_connections, boost::bind (&EngineStateController::_on_device_list_change, this) );
@@ -893,10 +894,9 @@ EngineStateController::_refresh_stereo_out_channel_states()
 void
 EngineStateController::_on_engine_running ()
 {
-    _update_device_channels_state();
     _serialize_and_save_current_state();
     
-    EngineRunning();
+    EngineRunning(); // emit a signal
 }
 
 
@@ -925,6 +925,15 @@ EngineStateController::_on_parameter_changed (const std::string& parameter_name)
 }
 
 
+void
+EngineStateController::_on_ports_registration_update ()
+{
+    _update_device_channels_state();
+    
+    PortRegistrationChanged(); // emit a signal
+}
+
+
 bool
 EngineStateController::push_current_state_to_backend(bool start)
 {