add GUI for midi-device settings (and properly indent the code)

2 files changed, 1548 insertions, 1369 deletions

diff --git a/gtk2_ardour/engine_dialog.cc b/gtk2_ardour/engine_dialog.cc
index 4ea7511ee2..a5accc6e9b 100644
--- a/gtk2_ardour/engine_dialog.cc
+++ b/gtk2_ardour/engine_dialog.cc
@@ -59,7 +59,7 @@ using namespace Gtkmm2ext;
 using namespace PBD;
 using namespace Glib;
 
-static const unsigned int midi_tab = -1; /* not currently in use */
+static const unsigned int midi_tab = 2;
 static const unsigned int latency_tab = 1; /* zero-based, page zero is the main setup page */
 
 static const char* results_markup = X_("<span foreground=\"red\" style=\"italic\" size=\"larger\">%1</span>");
@@ -78,19 +78,18 @@ EngineControl::EngineControl ()
 	, ports_adjustment (128, 8, 1024, 1, 16)
 	, ports_spinner (ports_adjustment)
 	, control_app_button (_("Device Control Panel"))
+	, midi_devices_button (_("Midi Device Setup"))
 	, lm_measure_label (_("Measure"))
 	, lm_use_button (_("Use results"))
 	, lm_back_button (_("Back to settings ... (ignore results)"))
 	, lm_button_audio (_("Calibrate Audio"))
-	, lm_button_midi (_("Calibrate Midi"))
 	, lm_table (12, 3)
 	, have_lm_results (false)
 	, lm_running (false)
-	, midi_refresh_button (_("Refresh list"))
+	, midi_back_button (_("Back to settings"))
 	, ignore_changes (0)
 	, _desired_sample_rate (0)
 	, started_at_least_once (false)
-	, _measure_midi(false)
 {
 	using namespace Notebook_Helpers;
 	vector<string> strings;
@@ -100,8 +99,7 @@ EngineControl::EngineControl ()
 
 	set_name (X_("AudioMIDISetup"));
 
-	/* the backend combo is the one thing that is ALWAYS visible 
-	 */
+	/* the backend combo is the one thing that is ALWAYS visible */
 
 	vector<const ARDOUR::AudioBackendInfo*> backends = ARDOUR::AudioEngine::instance()->available_backends();
 
@@ -131,17 +129,15 @@ EngineControl::EngineControl ()
 
 	basic_hbox.pack_start (basic_packer, false, false);
 
-	/* latency tab */
-
 	/* latency measurement tab */
-	
+
 	lm_title.set_markup (string_compose ("<span size=\"large\" weight=\"bold\">%1</span>", _("Latency Measurement Tool")));
-	
+
 	row = 0;
 	lm_table.set_row_spacings (12);
 	lm_table.set_col_spacings (6);
 	lm_table.set_homogeneous (false);
-	
+
 	lm_table.attach (lm_title, 0, 3, row, row+1, xopt, (AttachOptions) 0);
 	row++;
 
@@ -185,8 +181,8 @@ EngineControl::EngineControl ()
 	lm_measure_button.add (lm_measure_label);
 	lm_measure_button.signal_clicked().connect (sigc::mem_fun (*this, &EngineControl::latency_button_clicked));
 	lm_use_button.signal_clicked().connect (sigc::mem_fun (*this, &EngineControl::use_latency_button_clicked));
-	lm_back_button.signal_clicked().connect (sigc::bind (sigc::mem_fun (notebook, &Gtk::Notebook::set_current_page), 0));
-	
+	lm_back_button_signal = lm_back_button.signal_clicked().connect (sigc::bind (sigc::mem_fun (notebook, &Gtk::Notebook::set_current_page), 0));
+
 	lm_use_button.set_sensitive (false);
 
 	/* Increase the default spacing around the labels of these three
@@ -216,13 +212,13 @@ EngineControl::EngineControl ()
 	preamble->set_markup (_("When satisfied with the results, click the \"Use results\" button."));
 	lm_table.attach (*preamble, 0, 3, row, row+1, AttachOptions(FILL|EXPAND), (AttachOptions) 0);
 
-	++row; // skip a row in the table 
-	++row; // skip a row in the table 
+	++row; // skip a row in the table
+	++row; // skip a row in the table
 
 	lm_table.attach (lm_results, 0, 3, row, row+1, AttachOptions(FILL|EXPAND), (AttachOptions) 0);
 
-	++row; // skip a row in the table 
-	++row; // skip a row in the table 
+	++row; // skip a row in the table
+	++row; // skip a row in the table
 
 	lm_table.attach (lm_measure_button, 0, 1, row, row+1, AttachOptions(FILL|EXPAND), (AttachOptions) 0);
 	lm_table.attach (lm_use_button, 1, 2, row, row+1, AttachOptions(FILL|EXPAND), (AttachOptions) 0);
@@ -233,11 +229,13 @@ EngineControl::EngineControl ()
 	lm_vbox.set_border_width (12);
 	lm_vbox.pack_start (lm_table, false, false);
 
+	midi_back_button.signal_clicked().connect (sigc::bind (sigc::mem_fun (notebook, &Gtk::Notebook::set_current_page), 0));
+
 	/* pack it all up */
 
 	notebook.pages().push_back (TabElem (basic_vbox, _("Audio")));
-	// notebook.pages().push_back (TabElem (midi_vbox, _("MIDI")));
 	notebook.pages().push_back (TabElem (lm_vbox, _("Latency")));
+	notebook.pages().push_back (TabElem (midi_vbox, _("MIDI")));
 	notebook.set_border_width (12);
 
 	notebook.set_show_tabs (false);
@@ -257,6 +255,10 @@ EngineControl::EngineControl ()
 	input_channels.signal_output().connect (sigc::bind (sigc::ptr_fun (&EngineControl::print_channel_count), &input_channels));
 	output_channels.signal_output().connect (sigc::bind (sigc::ptr_fun (&EngineControl::print_channel_count), &output_channels));
 
+	midi_devices_button.signal_clicked.connect (mem_fun (*this, &EngineControl::configure_midi_devices));
+	midi_devices_button.set_sensitive (false);
+	midi_devices_button.set_name ("generic button");
+
 	control_app_button.signal_clicked().connect (mem_fun (*this, &EngineControl::control_app_button_clicked));
 	manage_control_app_sensitivity ();
 
@@ -292,1361 +294,1493 @@ EngineControl::EngineControl ()
 	}
 
 	notebook.signal_switch_page().connect (sigc::mem_fun (*this, &EngineControl::on_switch_page));
- }
-
- void
- EngineControl::on_response (int response_id)
- {
-	 ArdourDialog::on_response (response_id);
-
-	 switch (response_id) {
-	 case RESPONSE_APPLY:
-		 push_state_to_backend (true);
-		 break;
-	 case RESPONSE_OK:
-		 push_state_to_backend (true);
-		 hide ();
-		 break;
-	 case RESPONSE_DELETE_EVENT: {
-		 GdkEventButton ev;
-		 ev.type = GDK_BUTTON_PRESS;
-		 ev.button = 1;
-		 on_delete_event ((GdkEventAny*) &ev);
-		 break;
-	 }
-	 default:
-		 hide ();
-	 }
- }
-
- void
- EngineControl::build_notebook ()
- {
-	 Label* label;
-	 AttachOptions xopt = AttachOptions (FILL|EXPAND);
-
-	 /* clear the table */
-
-	 Gtkmm2ext::container_clear (basic_vbox);
-	 Gtkmm2ext::container_clear (basic_packer);
-
-	 if (control_app_button.get_parent()) {
-		 control_app_button.get_parent()->remove (control_app_button);
-	 }
-
-	 label = manage (left_aligned_label (_("Audio System:")));
-	 basic_packer.attach (*label, 0, 1, 0, 1, xopt, (AttachOptions) 0);
-	 basic_packer.attach (backend_combo, 1, 2, 0, 1, xopt, (AttachOptions) 0);
-
-	 lm_button_audio.signal_clicked.connect (sigc::mem_fun (*this, &EngineControl::calibrate_audio_latency));
-	 lm_button_audio.set_name ("generic button");
-
-	 lm_button_midi.signal_clicked.connect (sigc::mem_fun (*this, &EngineControl::calibrate_midi_latency));
-	 lm_button_midi.set_name ("generic button");
-
-	 if (_have_control) {
-		 build_full_control_notebook ();
-	 } else {
-		 build_no_control_notebook ();
-	 }
-
-	 basic_vbox.pack_start (basic_hbox, false, false);
-
-	 if (_have_control) {
-		 Gtk::HBox* hpacker = manage (new HBox);
-		 hpacker->set_border_width (12);
-		 hpacker->pack_start (control_app_button, false, false);
-		 hpacker->show ();
-		 control_app_button.show();
-		 basic_vbox.pack_start (*hpacker);
-	 }
-
-	 basic_vbox.show_all ();
- }
-
- void
- EngineControl::build_full_control_notebook ()
- {
-	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
-	 assert (backend);
-
-	 using namespace Notebook_Helpers;
-	 Label* label;
-	 vector<string> strings;
-	 AttachOptions xopt = AttachOptions (FILL|EXPAND);
-	 int row = 1; // row zero == backend combo
-
-	 /* start packing it up */
-
-	 if (backend->requires_driver_selection()) {
-		 label = manage (left_aligned_label (_("Driver:")));
-		 basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
-		 basic_packer.attach (driver_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
-		 row++;
-	 }
-
-	 label = manage (left_aligned_label (_("Device:")));
-	 basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
-	 basic_packer.attach (device_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
-	 row++;
-
-	 label = manage (left_aligned_label (_("Sample rate:")));
-	 basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
-	 basic_packer.attach (sample_rate_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
-	 row++;
-
-
-	 label = manage (left_aligned_label (_("Buffer size:")));
-	 basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
-	 basic_packer.attach (buffer_size_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
-	 buffer_size_duration_label.set_alignment (0.0); /* left-align */
-	 basic_packer.attach (buffer_size_duration_label, 2, 3, row, row+1, SHRINK, (AttachOptions) 0);
-	 row++;
-
-	 input_channels.set_name ("InputChannels");
-	 input_channels.set_flags(Gtk::CAN_FOCUS);
-	 input_channels.set_digits(0);
-	 input_channels.set_wrap(false);
-	 output_channels.set_editable (true);
-
-	 label = manage (left_aligned_label (_("Input Channels:")));
-	 basic_packer.attach (*label, 0, 1, row, row+1, xopt, (AttachOptions) 0);
-	 basic_packer.attach (input_channels, 1, 2, row, row+1, xopt, (AttachOptions) 0);
-	 ++row;
-
-	 output_channels.set_name ("OutputChannels");
-	 output_channels.set_flags(Gtk::CAN_FOCUS);
-	 output_channels.set_digits(0);
-	 output_channels.set_wrap(false);
-	 output_channels.set_editable (true);
-
-	 label = manage (left_aligned_label (_("Output Channels:")));
-	 basic_packer.attach (*label, 0, 1, row, row+1, xopt, (AttachOptions) 0);
-	 basic_packer.attach (output_channels, 1, 2, row, row+1, xopt, (AttachOptions) 0);
-	 ++row;
-
-	 input_latency.set_name ("InputLatency");
-	 input_latency.set_flags(Gtk::CAN_FOCUS);
-	 input_latency.set_digits(0);
-	 input_latency.set_wrap(false);
-	 input_latency.set_editable (true);
-
-	 label = manage (left_aligned_label (_("Hardware input latency:")));
-	 basic_packer.attach (*label, 0, 1, row, row+1, xopt, (AttachOptions) 0);
-	 basic_packer.attach (input_latency, 1, 2, row, row+1, xopt, (AttachOptions) 0);
-	 label = manage (left_aligned_label (_("samples")));
-	 basic_packer.attach (*label, 2, 3, row, row+1, SHRINK, (AttachOptions) 0);
-	 ++row;
-
-	 output_latency.set_name ("OutputLatency");
-	 output_latency.set_flags(Gtk::CAN_FOCUS);
-	 output_latency.set_digits(0);
-	 output_latency.set_wrap(false);
-	 output_latency.set_editable (true);
-
-	 label = manage (left_aligned_label (_("Hardware output latency:")));
-	 basic_packer.attach (*label, 0, 1, row, row+1, xopt, (AttachOptions) 0);
-	 basic_packer.attach (output_latency, 1, 2, row, row+1, xopt, (AttachOptions) 0);
-	 label = manage (left_aligned_label (_("samples")));
-	 basic_packer.attach (*label, 2, 3, row, row+1, SHRINK, (AttachOptions) 0);
-
-	 /* button spans 2 rows */
-
-	 basic_packer.attach (lm_button_audio, 3, 4, row-1, row+1, xopt, xopt);
-	 ++row;
-
-	 label = manage (left_aligned_label (_("MIDI System")));
-	 basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
-	 basic_packer.attach (midi_option_combo, 1, 2, row, row + 1, SHRINK, (AttachOptions) 0);
-	 basic_packer.attach (lm_button_midi, 3, 4, row, row+1, xopt, xopt);
-	 row++;
- }
-
- void
- EngineControl::build_no_control_notebook ()
- {
-	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
-	 assert (backend);
-
-	 using namespace Notebook_Helpers;
-	 Label* label;
-	 vector<string> strings;
-	 AttachOptions xopt = AttachOptions (FILL|EXPAND);
-	 int row = 1; // row zero == backend combo
-	 const string msg = string_compose (_("The %1 audio backend was configured and started externally.\nThis limits your control over it."), backend->name());
-
-	 label = manage (new Label);
-	 label->set_markup (string_compose ("<span weight=\"bold\" foreground=\"red\">%1</span>", msg));
-	 basic_packer.attach (*label, 0, 2, row, row + 1, xopt, (AttachOptions) 0);
-	 row++;
-
-	 if (backend->can_change_sample_rate_when_running()) {
-		 label = manage (left_aligned_label (_("Sample rate:")));
-		 basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
-		 basic_packer.attach (sample_rate_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
-		 row++;
-	 }
-
-	 if (backend->can_change_buffer_size_when_running()) {
-		 label = manage (left_aligned_label (_("Buffer size:")));
-		 basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
-		 basic_packer.attach (buffer_size_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
-		 buffer_size_duration_label.set_alignment (0.0); /* left-align */
-		 basic_packer.attach (buffer_size_duration_label, 2, 3, row, row+1, xopt, (AttachOptions) 0);
-		 row++;
-	 }
-
-	 connect_disconnect_button.signal_clicked().connect (sigc::mem_fun (*this, &EngineControl::connect_disconnect_click));
-
-	 basic_packer.attach (connect_disconnect_button, 0, 2, row, row+1, FILL, AttachOptions (0));
-	 row++;
- }
-
- EngineControl::~EngineControl ()
- {
-	 ignore_changes = true;
- }
-
- void
- EngineControl::disable_latency_tab ()
- {
-	 vector<string> empty;
-	 set_popdown_strings (lm_output_channel_combo, empty);
-	 set_popdown_strings (lm_input_channel_combo, empty);
-	 lm_measure_button.set_sensitive (false);
-	 lm_use_button.set_sensitive (false);
- }
-
- void
- EngineControl::enable_latency_tab ()
- {
-	 vector<string> outputs;
-	 vector<string> inputs;
-
-	 ARDOUR::DataType const type = _measure_midi ? ARDOUR::DataType::MIDI : ARDOUR::DataType::AUDIO;
-	 ARDOUR::AudioEngine::instance()->get_physical_outputs (type, outputs);
-	 ARDOUR::AudioEngine::instance()->get_physical_inputs (type, inputs);
-
-	 if (inputs.empty() || outputs.empty()) {
-		 MessageDialog msg (_("Your selected audio configuration is playback- or capture-only.\n\nLatency calibration requires playback and capture"));
-		 lm_measure_button.set_sensitive (false);
-		 notebook.set_current_page (0);
-		 msg.run ();
-		 return;
-	 }
-
-	 if (!outputs.empty()) {
-		 set_popdown_strings (lm_output_channel_combo, outputs);
-		 lm_output_channel_combo.set_active_text (outputs.front());
-		 lm_output_channel_combo.set_sensitive (true);
-	 } else {
-		 lm_output_channel_combo.set_sensitive (false);
-	 }
-
-	 if (!inputs.empty()) {
-		 set_popdown_strings (lm_input_channel_combo, inputs);
-		 lm_input_channel_combo.set_active_text (inputs.front());
-		 lm_input_channel_combo.set_sensitive (true);
-	 } else {
-		 lm_input_channel_combo.set_sensitive (false);
-	 }
-
-	 lm_measure_button.set_sensitive (true);
- }
-
- void
- EngineControl::setup_midi_tab_for_backend ()
- {
-	 string backend = backend_combo.get_active_text ();
-
-	 Gtkmm2ext::container_clear (midi_vbox);
-
-	 midi_vbox.set_border_width (12);
-	 midi_device_table.set_border_width (12);
-
-	 if (backend == "JACK") {
-		 setup_midi_tab_for_jack ();
-	 }
-
-	 midi_vbox.pack_start (midi_device_table, true, true);
-	 midi_vbox.pack_start (midi_refresh_button, false, false);
-	 midi_vbox.show_all ();
-
-	 midi_refresh_button.signal_clicked().connect (sigc::mem_fun (*this, &EngineControl::refresh_midi_display));
- }
-
- void
- EngineControl::setup_midi_tab_for_jack ()
- {
- }	
-
- void
- EngineControl::refresh_midi_display ()
- {
-	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
-	 assert (backend);
-
-	 vector<string> midi_inputs;
-	 vector<string> midi_outputs;
-	 int row  = 0;
-	 AttachOptions xopt = AttachOptions (FILL|EXPAND);
-	 Gtk::Label* l;
-
-	 Gtkmm2ext::container_clear (midi_device_table);
-
-	 backend->get_physical_inputs (ARDOUR::DataType::MIDI, midi_inputs);
-	 backend->get_physical_outputs (ARDOUR::DataType::MIDI, midi_outputs);
-
-	 midi_device_table.set_spacings (6);
-	 midi_device_table.set_homogeneous (true);
-	 midi_device_table.resize (midi_inputs.size() + midi_outputs.size() + 3, 1);
-
-	 l = manage (new Label);
-	 l->set_markup (string_compose ("<span size=\"large\" weight=\"bold\">%1</span>", _("MIDI Inputs")));
-	 midi_device_table.attach (*l, 0, 1, row, row + 1, xopt, AttachOptions (0));
-	 l->set_alignment (0, 0.5);
-	 row++;
-	 l->show ();
-
-	 for (vector<string>::iterator p = midi_inputs.begin(); p != midi_inputs.end(); ++p) {
-		 l = manage (new Label ((*p).substr ((*p).find_last_of (':') + 1)));
-		 l->set_alignment (0, 0.5);
-		 midi_device_table.attach (*l, 0, 1, row, row + 1, xopt, AttachOptions (0));
-		 l->show ();
-		 row++;
-	 }
-
-	 row++; // extra row of spacing
-
-	 l = manage (new Label);
-	 l->set_markup (string_compose ("<span size=\"large\" weight=\"bold\">%1</span>", _("MIDI Outputs")));
-	 midi_device_table.attach (*l, 0, 1, row, row + 1, xopt, AttachOptions (0));
-	 l->set_alignment (0, 0.5);
-	 row++;
-	 l->show ();
-
-	 for (vector<string>::iterator p = midi_outputs.begin(); p != midi_outputs.end(); ++p) {
-		 l = manage (new Label ((*p).substr ((*p).find_last_of (':') + 1)));
-		 l->set_alignment (0, 0.5);
-		 midi_device_table.attach (*l, 0, 1, row, row + 1, xopt, AttachOptions (0));
-		 l->show ();
-		 row++;
-	 }
- }
-
- void
- EngineControl::update_sensitivity ()
- {
- }
-
- void
- EngineControl::backend_changed ()
- {
-	 string backend_name = backend_combo.get_active_text();
-	 boost::shared_ptr<ARDOUR::AudioBackend> backend;
-
-	 if (!(backend = ARDOUR::AudioEngine::instance()->set_backend (backend_name, "ardour", ""))) {
-		 /* eh? setting the backend failed... how ? */
-		 return;
-	 }
-
-	 _have_control = ARDOUR::AudioEngine::instance()->setup_required ();
-
-	 build_notebook ();
-	 setup_midi_tab_for_backend ();
-
-	 if (backend->requires_driver_selection()) {
-		 vector<string> drivers = backend->enumerate_drivers();
-		 driver_combo.set_sensitive (true);
-
-		 if (!drivers.empty()) {
-			 {
-				 PBD::Unwinder<uint32_t> protect_ignore_changes (ignore_changes, ignore_changes + 1);
-				 set_popdown_strings (driver_combo, drivers);
-				 driver_combo.set_active_text (drivers.front());
-			 }
-
-			 driver_changed ();
-		 }
-
-	 } else {
-		 driver_combo.set_sensitive (false);
-		 /* this will change the device text which will cause a call to
-		  * device changed which will set up parameters
-		  */
-		 list_devices ();
-	 }
-
-	 vector<string> midi_options = backend->enumerate_midi_options();
-
-	 if (midi_options.size() == 1) {
-		 /* only contains the "none" option */
-		 midi_option_combo.set_sensitive (false);
-	 } else {
-		 if (_have_control) {
-			 set_popdown_strings (midi_option_combo, midi_options);
-			 midi_option_combo.set_active_text (midi_options.front());
-			 midi_option_combo.set_sensitive (true);
-		 } else {
-			 midi_option_combo.set_sensitive (false);
-		 }
-	 }
-	 started_at_least_once = false;
-
-	 if (!ignore_changes) {
-		 maybe_display_saved_state ();
-	 }
- }
-
- bool
- EngineControl::print_channel_count (Gtk::SpinButton* sb)
- {
-	 uint32_t cnt = (uint32_t) sb->get_value();
-	 if (cnt == 0) {
-		 sb->set_text (_("all available channels"));
-	 } else {
-		 char buf[32];
-		 snprintf (buf, sizeof (buf), "%d", cnt);
-		 sb->set_text (buf);
-	 }
-	 return true;
- }
-
- void
- EngineControl::list_devices ()
- {
-	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
-	 assert (backend);
-
-	 /* now fill out devices, mark sample rates, buffer sizes insensitive */
-
-	 vector<ARDOUR::AudioBackend::DeviceStatus> all_devices = backend->enumerate_devices ();
-
-	 /* NOTE: Ardour currently does not display the "available" field of the
-	  * returned devices.
-	  *
-	  * Doing so would require a different GUI widget than the combo
-	  * box/popdown that we currently use, since it has no way to list
-	  * items that are not selectable. Something more like a popup menu,
-	  * which could have unselectable items, would be appropriate.
-	  */
-
-	 vector<string> available_devices;
-
-	 for (vector<ARDOUR::AudioBackend::DeviceStatus>::const_iterator i = all_devices.begin(); i != all_devices.end(); ++i) {
-		 available_devices.push_back (i->name);
-	 }
-
-	 if (!available_devices.empty()) {
-
-		 update_sensitivity ();
-
-		 {
-			 PBD::Unwinder<uint32_t> protect_ignore_changes (ignore_changes, ignore_changes + 1);
-			 set_popdown_strings (device_combo, available_devices);
-			 device_combo.set_active_text (available_devices.front());
-		 }
-
-		 device_changed ();
-
-		 ok_button->set_sensitive (true);
-		 apply_button->set_sensitive (true);
-
-	 } else {
-		 sample_rate_combo.set_sensitive (false);
-		 buffer_size_combo.set_sensitive (false);
-		 input_latency.set_sensitive (false);
-		 output_latency.set_sensitive (false);
-		 input_channels.set_sensitive (false);
-		 output_channels.set_sensitive (false);
-		 ok_button->set_sensitive (false);
-		 apply_button->set_sensitive (false);
-	 }
- }
-
- void
- EngineControl::driver_changed ()
- {
-	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
-	 assert (backend);
-
-	 backend->set_driver (driver_combo.get_active_text());
-	 list_devices ();
-
-	 if (!ignore_changes) {
-		 maybe_display_saved_state ();
-	 }
- }
-
- void
- EngineControl::device_changed ()
- {
-
-	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
-	 assert (backend);
-	 string device_name = device_combo.get_active_text ();
-	 vector<string> s;
-
-	 {
-		 PBD::Unwinder<uint32_t> protect_ignore_changes (ignore_changes, ignore_changes + 1);
-
-		 /* don't allow programmatic change to combos to cause a
-		    recursive call to this method.
+}
+
+void
+EngineControl::on_response (int response_id)
+{
+	ArdourDialog::on_response (response_id);
+
+	switch (response_id) {
+		case RESPONSE_APPLY:
+			push_state_to_backend (true);
+			break;
+		case RESPONSE_OK:
+			push_state_to_backend (true);
+			hide ();
+			break;
+		case RESPONSE_DELETE_EVENT:
+			{
+				GdkEventButton ev;
+				ev.type = GDK_BUTTON_PRESS;
+				ev.button = 1;
+				on_delete_event ((GdkEventAny*) &ev);
+				break;
+			}
+		default:
+			hide ();
+	}
+}
+
+void
+EngineControl::build_notebook ()
+{
+	Label* label;
+	AttachOptions xopt = AttachOptions (FILL|EXPAND);
+
+	/* clear the table */
+
+	Gtkmm2ext::container_clear (basic_vbox);
+	Gtkmm2ext::container_clear (basic_packer);
+
+	if (control_app_button.get_parent()) {
+		control_app_button.get_parent()->remove (control_app_button);
+	}
+
+	label = manage (left_aligned_label (_("Audio System:")));
+	basic_packer.attach (*label, 0, 1, 0, 1, xopt, (AttachOptions) 0);
+	basic_packer.attach (backend_combo, 1, 2, 0, 1, xopt, (AttachOptions) 0);
+
+	lm_button_audio.signal_clicked.connect (sigc::mem_fun (*this, &EngineControl::calibrate_audio_latency));
+	lm_button_audio.set_name ("generic button");
+
+	if (_have_control) {
+		build_full_control_notebook ();
+	} else {
+		build_no_control_notebook ();
+	}
+
+	basic_vbox.pack_start (basic_hbox, false, false);
+
+	if (_have_control) {
+		Gtk::HBox* hpacker = manage (new HBox);
+		hpacker->set_border_width (12);
+		hpacker->pack_start (control_app_button, false, false);
+		hpacker->show ();
+		control_app_button.show();
+		basic_vbox.pack_start (*hpacker);
+	}
+
+	basic_vbox.show_all ();
+}
+
+void
+EngineControl::build_full_control_notebook ()
+{
+	boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
+	assert (backend);
+
+	using namespace Notebook_Helpers;
+	Label* label;
+	vector<string> strings;
+	AttachOptions xopt = AttachOptions (FILL|EXPAND);
+	int row = 1; // row zero == backend combo
+
+	/* start packing it up */
+
+	if (backend->requires_driver_selection()) {
+		label = manage (left_aligned_label (_("Driver:")));
+		basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
+		basic_packer.attach (driver_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
+		row++;
+	}
+
+	label = manage (left_aligned_label (_("Device:")));
+	basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
+	basic_packer.attach (device_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
+	row++;
+
+	label = manage (left_aligned_label (_("Sample rate:")));
+	basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
+	basic_packer.attach (sample_rate_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
+	row++;
+
+
+	label = manage (left_aligned_label (_("Buffer size:")));
+	basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
+	basic_packer.attach (buffer_size_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
+	buffer_size_duration_label.set_alignment (0.0); /* left-align */
+	basic_packer.attach (buffer_size_duration_label, 2, 3, row, row+1, SHRINK, (AttachOptions) 0);
+	row++;
+
+	input_channels.set_name ("InputChannels");
+	input_channels.set_flags (Gtk::CAN_FOCUS);
+	input_channels.set_digits (0);
+	input_channels.set_wrap (false);
+	output_channels.set_editable (true);
+
+	label = manage (left_aligned_label (_("Input Channels:")));
+	basic_packer.attach (*label, 0, 1, row, row+1, xopt, (AttachOptions) 0);
+	basic_packer.attach (input_channels, 1, 2, row, row+1, xopt, (AttachOptions) 0);
+	++row;
+
+	output_channels.set_name ("OutputChannels");
+	output_channels.set_flags (Gtk::CAN_FOCUS);
+	output_channels.set_digits (0);
+	output_channels.set_wrap (false);
+	output_channels.set_editable (true);
+
+	label = manage (left_aligned_label (_("Output Channels:")));
+	basic_packer.attach (*label, 0, 1, row, row+1, xopt, (AttachOptions) 0);
+	basic_packer.attach (output_channels, 1, 2, row, row+1, xopt, (AttachOptions) 0);
+	++row;
+
+	input_latency.set_name ("InputLatency");
+	input_latency.set_flags (Gtk::CAN_FOCUS);
+	input_latency.set_digits (0);
+	input_latency.set_wrap (false);
+	input_latency.set_editable (true);
+
+	label = manage (left_aligned_label (_("Hardware input latency:")));
+	basic_packer.attach (*label, 0, 1, row, row+1, xopt, (AttachOptions) 0);
+	basic_packer.attach (input_latency, 1, 2, row, row+1, xopt, (AttachOptions) 0);
+	label = manage (left_aligned_label (_("samples")));
+	basic_packer.attach (*label, 2, 3, row, row+1, SHRINK, (AttachOptions) 0);
+	++row;
+
+	output_latency.set_name ("OutputLatency");
+	output_latency.set_flags (Gtk::CAN_FOCUS);
+	output_latency.set_digits (0);
+	output_latency.set_wrap (false);
+	output_latency.set_editable (true);
+
+	label = manage (left_aligned_label (_("Hardware output latency:")));
+	basic_packer.attach (*label, 0, 1, row, row+1, xopt, (AttachOptions) 0);
+	basic_packer.attach (output_latency, 1, 2, row, row+1, xopt, (AttachOptions) 0);
+	label = manage (left_aligned_label (_("samples")));
+	basic_packer.attach (*label, 2, 3, row, row+1, SHRINK, (AttachOptions) 0);
+
+	/* button spans 2 rows */
+
+	basic_packer.attach (lm_button_audio, 3, 4, row-1, row+1, xopt, xopt);
+	++row;
+
+	label = manage (left_aligned_label (_("MIDI System")));
+	basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
+	basic_packer.attach (midi_option_combo, 1, 2, row, row + 1, SHRINK, (AttachOptions) 0);
+	basic_packer.attach (midi_devices_button, 3, 4, row, row+1, xopt, xopt);
+	row++;
+}
+
+void
+EngineControl::build_no_control_notebook ()
+{
+	boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
+	assert (backend);
+
+	using namespace Notebook_Helpers;
+	Label* label;
+	vector<string> strings;
+	AttachOptions xopt = AttachOptions (FILL|EXPAND);
+	int row = 1; // row zero == backend combo
+	const string msg = string_compose (_("The %1 audio backend was configured and started externally.\nThis limits your control over it."), backend->name());
+
+	label = manage (new Label);
+	label->set_markup (string_compose ("<span weight=\"bold\" foreground=\"red\">%1</span>", msg));
+	basic_packer.attach (*label, 0, 2, row, row + 1, xopt, (AttachOptions) 0);
+	row++;
+
+	if (backend->can_change_sample_rate_when_running()) {
+		label = manage (left_aligned_label (_("Sample rate:")));
+		basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
+		basic_packer.attach (sample_rate_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
+		row++;
+	}
+
+	if (backend->can_change_buffer_size_when_running()) {
+		label = manage (left_aligned_label (_("Buffer size:")));
+		basic_packer.attach (*label, 0, 1, row, row + 1, xopt, (AttachOptions) 0);
+		basic_packer.attach (buffer_size_combo, 1, 2, row, row + 1, xopt, (AttachOptions) 0);
+		buffer_size_duration_label.set_alignment (0.0); /* left-align */
+		basic_packer.attach (buffer_size_duration_label, 2, 3, row, row+1, xopt, (AttachOptions) 0);
+		row++;
+	}
+
+	connect_disconnect_button.signal_clicked().connect (sigc::mem_fun (*this, &EngineControl::connect_disconnect_click));
+
+	basic_packer.attach (connect_disconnect_button, 0, 2, row, row+1, FILL, AttachOptions (0));
+	row++;
+}
+
+EngineControl::~EngineControl ()
+{
+	ignore_changes = true;
+}
+
+void
+EngineControl::disable_latency_tab ()
+{
+	vector<string> empty;
+	set_popdown_strings (lm_output_channel_combo, empty);
+	set_popdown_strings (lm_input_channel_combo, empty);
+	lm_measure_button.set_sensitive (false);
+	lm_use_button.set_sensitive (false);
+}
+
+void
+EngineControl::enable_latency_tab ()
+{
+	vector<string> outputs;
+	vector<string> inputs;
+
+	ARDOUR::DataType const type = _measure_midi ? ARDOUR::DataType::MIDI : ARDOUR::DataType::AUDIO;
+	ARDOUR::AudioEngine::instance()->get_physical_outputs (type, outputs);
+	ARDOUR::AudioEngine::instance()->get_physical_inputs (type, inputs);
+
+	if (inputs.empty() || outputs.empty()) {
+		MessageDialog msg (_("Your selected audio configuration is playback- or capture-only.\n\nLatency calibration requires playback and capture"));
+		lm_measure_button.set_sensitive (false);
+		notebook.set_current_page (0);
+		msg.run ();
+		return;
+	}
+
+	if (!outputs.empty()) {
+		set_popdown_strings (lm_output_channel_combo, outputs);
+		lm_output_channel_combo.set_active_text (outputs.front());
+		lm_output_channel_combo.set_sensitive (true);
+	} else {
+		lm_output_channel_combo.set_sensitive (false);
+	}
+
+	if (!inputs.empty()) {
+		set_popdown_strings (lm_input_channel_combo, inputs);
+		lm_input_channel_combo.set_active_text (inputs.front());
+		lm_input_channel_combo.set_sensitive (true);
+	} else {
+		lm_input_channel_combo.set_sensitive (false);
+	}
+
+	lm_measure_button.set_sensitive (true);
+}
+
+void
+EngineControl::setup_midi_tab_for_backend ()
+{
+	string backend = backend_combo.get_active_text ();
+
+	Gtkmm2ext::container_clear (midi_vbox);
+
+	midi_vbox.set_border_width (12);
+	midi_device_table.set_border_width (12);
+
+	if (backend == "JACK") {
+		setup_midi_tab_for_jack ();
+	}
+
+	midi_vbox.pack_start (midi_device_table, true, true);
+	midi_vbox.pack_start (midi_back_button, false, false);
+	midi_vbox.show_all ();
+}
+
+void
+EngineControl::setup_midi_tab_for_jack ()
+{
+}
+
+void
+EngineControl::midi_latency_adjustment_changed (Gtk::Adjustment *a, MidiDeviceSettings device, bool for_input) {
+	if (for_input) {
+		device->input_latency = a->get_value();
+	} else {
+		device->output_latency = a->get_value();
+	}
+}
+
+bool
+EngineControl::midi_device_enabled_toggled (GdkEventButton* ev, ArdourButton *b, MidiDeviceSettings device) {
+	if (ev->type == GDK_2BUTTON_PRESS || ev->type == GDK_3BUTTON_PRESS) {
+		return true;
+	}
+	b->set_active (!b->get_active());
+	device->enabled = b->get_active();
+	refresh_midi_display();
+	return true;
+}
+
+void
+EngineControl::refresh_midi_display ()
+{
+	boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
+	assert (backend);
+
+	int row  = 0;
+	AttachOptions xopt = AttachOptions (FILL|EXPAND);
+	Gtk::Label* l;
+
+	Gtkmm2ext::container_clear (midi_device_table);
+
+	midi_device_table.set_spacings (6);
+
+	l = manage (new Label);
+	l->set_markup (string_compose ("<span size=\"large\" weight=\"bold\">%1</span>", _("MIDI Devices")));
+	midi_device_table.attach (*l, 0, 4, row, row + 1, xopt, AttachOptions (0));
+	l->set_alignment (0.5, 0.5);
+	row++;
+	l->show ();
+
+	l = manage (new Label (_("Device"))); l->show (); l->set_alignment (0.5, 0.5);
+	midi_device_table.attach (*l, 0, 1, row, row + 2, xopt, AttachOptions (0));
+	l = manage (new Label (_("Hardware Latencies"))); l->show (); l->set_alignment (0.5, 0.5);
+	midi_device_table.attach (*l, 1, 3, row, row + 1, xopt, AttachOptions (0));
+	row++;
+	l = manage (new Label (_("Input"))); l->show (); l->set_alignment (0.5, 0.5);
+	midi_device_table.attach (*l, 1, 2, row, row + 1, xopt, AttachOptions (0));
+	l = manage (new Label (_("Output"))); l->show (); l->set_alignment (0.5, 0.5);
+	midi_device_table.attach (*l, 2, 3, row, row + 1, xopt, AttachOptions (0));
+	row++;
+
+	for (vector<MidiDeviceSettings>::const_iterator p = _midi_devices.begin(); p != _midi_devices.end(); ++p) {
+		ArdourButton *m;
+		Gtk::Button* b;
+		Gtk::Adjustment *a;
+		Gtk::SpinButton *s;
+		bool enabled = (*p)->enabled;
+
+		m = manage (new ArdourButton ((*p)->name, ArdourButton::led_default_elements));
+		m->set_name ("midi device");
+		m->add_events (Gdk::BUTTON_RELEASE_MASK);
+		m->set_active (enabled);
+		m->signal_button_release_event().connect (sigc::bind (sigc::mem_fun (*this, &EngineControl::midi_device_enabled_toggled), m, *p));
+		midi_device_table.attach (*m, 0, 1, row, row + 1, xopt, AttachOptions (0)); m->show ();
+
+		a = manage (new Gtk::Adjustment (0, 0, 99999, 1));
+		s = manage (new Gtk::SpinButton (*a));
+		a->set_value ((*p)->input_latency);
+		s->signal_value_changed().connect (sigc::bind (sigc::mem_fun (*this, &EngineControl::midi_latency_adjustment_changed), a, *p, true));
+		s->set_sensitive (_can_set_midi_latencies && enabled);
+		midi_device_table.attach (*s, 1, 2, row, row + 1, xopt, AttachOptions (0)); s->show ();
+
+		a = manage (new Gtk::Adjustment (0, 0, 99999, 1));
+		s = manage (new Gtk::SpinButton (*a));
+		a->set_value ((*p)->output_latency);
+		s->signal_value_changed().connect (sigc::bind (sigc::mem_fun (*this, &EngineControl::midi_latency_adjustment_changed), a, *p, false));
+		s->set_sensitive (_can_set_midi_latencies && enabled);
+		midi_device_table.attach (*s, 2, 3, row, row + 1, xopt, AttachOptions (0)); s->show ();
+
+		b = manage (new Button (_("Calibrate")));
+		b->signal_clicked().connect (sigc::bind (sigc::mem_fun (*this, &EngineControl::calibrate_midi_latency), *p));
+		b->set_sensitive (_can_set_midi_latencies && enabled);
+		midi_device_table.attach (*b, 3, 4, row, row + 1, xopt, AttachOptions (0)); b->show ();
+
+		row++;
+	}
+}
+
+void
+EngineControl::update_sensitivity ()
+{
+}
+
+void
+EngineControl::backend_changed ()
+{
+	string backend_name = backend_combo.get_active_text();
+	boost::shared_ptr<ARDOUR::AudioBackend> backend;
+
+	if (!(backend = ARDOUR::AudioEngine::instance()->set_backend (backend_name, "ardour", ""))) {
+		/* eh? setting the backend failed... how ? */
+		return;
+	}
+
+	_have_control = ARDOUR::AudioEngine::instance()->setup_required ();
+
+	build_notebook ();
+	setup_midi_tab_for_backend ();
+	_midi_devices.clear();
+
+	if (backend->requires_driver_selection()) {
+		vector<string> drivers = backend->enumerate_drivers();
+		driver_combo.set_sensitive (true);
+
+		if (!drivers.empty()) {
+			{
+				PBD::Unwinder<uint32_t> protect_ignore_changes (ignore_changes, ignore_changes + 1);
+				set_popdown_strings (driver_combo, drivers);
+				driver_combo.set_active_text (drivers.front());
+			}
+
+			driver_changed ();
+		}
+
+	} else {
+		driver_combo.set_sensitive (false);
+		/* this will change the device text which will cause a call to
+		 * device changed which will set up parameters
+		 */
+		list_devices ();
+	}
+
+	vector<string> midi_options = backend->enumerate_midi_options();
+
+	if (midi_options.size() == 1) {
+		/* only contains the "none" option */
+		midi_option_combo.set_sensitive (false);
+	} else {
+		if (_have_control) {
+			set_popdown_strings (midi_option_combo, midi_options);
+			midi_option_combo.set_active_text (midi_options.front());
+			midi_option_combo.set_sensitive (true);
+		} else {
+			midi_option_combo.set_sensitive (false);
+		}
+	}
+
+	midi_option_changed();
+
+	started_at_least_once = false;
+
+	if (!ignore_changes) {
+		maybe_display_saved_state ();
+	}
+}
+
+bool
+EngineControl::print_channel_count (Gtk::SpinButton* sb)
+{
+	uint32_t cnt = (uint32_t) sb->get_value();
+	if (cnt == 0) {
+		sb->set_text (_("all available channels"));
+	} else {
+		char buf[32];
+		snprintf (buf, sizeof (buf), "%d", cnt);
+		sb->set_text (buf);
+	}
+	return true;
+}
+
+void
+EngineControl::list_devices ()
+{
+	boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
+	assert (backend);
+
+	/* now fill out devices, mark sample rates, buffer sizes insensitive */
+
+	vector<ARDOUR::AudioBackend::DeviceStatus> all_devices = backend->enumerate_devices ();
+
+	/* NOTE: Ardour currently does not display the "available" field of the
+	 * returned devices.
+	 *
+	 * Doing so would require a different GUI widget than the combo
+	 * box/popdown that we currently use, since it has no way to list
+	 * items that are not selectable. Something more like a popup menu,
+	 * which could have unselectable items, would be appropriate.
+	 */
+
+	vector<string> available_devices;
+
+	for (vector<ARDOUR::AudioBackend::DeviceStatus>::const_iterator i = all_devices.begin(); i != all_devices.end(); ++i) {
+		available_devices.push_back (i->name);
+	}
+
+	if (!available_devices.empty()) {
+
+		update_sensitivity ();
+
+		{
+			PBD::Unwinder<uint32_t> protect_ignore_changes (ignore_changes, ignore_changes + 1);
+			set_popdown_strings (device_combo, available_devices);
+			device_combo.set_active_text (available_devices.front());
+		}
+
+		device_changed ();
+
+		ok_button->set_sensitive (true);
+		apply_button->set_sensitive (true);
+
+	} else {
+		sample_rate_combo.set_sensitive (false);
+		buffer_size_combo.set_sensitive (false);
+		input_latency.set_sensitive (false);
+		output_latency.set_sensitive (false);
+		input_channels.set_sensitive (false);
+		output_channels.set_sensitive (false);
+		ok_button->set_sensitive (false);
+		apply_button->set_sensitive (false);
+	}
+}
+
+void
+EngineControl::driver_changed ()
+{
+	boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
+	assert (backend);
+
+	backend->set_driver (driver_combo.get_active_text());
+	list_devices ();
+
+	if (!ignore_changes) {
+		maybe_display_saved_state ();
+	}
+}
+
+void
+EngineControl::device_changed ()
+{
+
+	boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
+	assert (backend);
+	string device_name = device_combo.get_active_text ();
+	vector<string> s;
+
+	{
+		PBD::Unwinder<uint32_t> protect_ignore_changes (ignore_changes, ignore_changes + 1);
+
+		/* don't allow programmatic change to combos to cause a
+		   recursive call to this method.
 		 */
 
-		 /* sample rates */
-
-		 string desired;
-
-		 vector<float> sr;
-
-		 if (_have_control) {
-			 sr = backend->available_sample_rates (device_name);
-		 } else {
-
-			 sr.push_back (8000.0f);
-			 sr.push_back (16000.0f);
-			 sr.push_back (32000.0f);
-			 sr.push_back (44100.0f);
-			 sr.push_back (48000.0f);
-			 sr.push_back (88200.0f);
-			 sr.push_back (96000.0f);
-			 sr.push_back (192000.0f);
-			 sr.push_back (384000.0f);
-		 }
-
-		 for (vector<float>::const_iterator x = sr.begin(); x != sr.end(); ++x) {
-			 s.push_back (rate_as_string (*x));
-			 if (*x == _desired_sample_rate) {
-				 desired = s.back();
-			 }
-		 }
-
-		 if (!s.empty()) {
-			 sample_rate_combo.set_sensitive (true);
-			 set_popdown_strings (sample_rate_combo, s);
-
-			 if (desired.empty()) {
-				 sample_rate_combo.set_active_text (rate_as_string (backend->default_sample_rate()));
-			 } else {
-				 sample_rate_combo.set_active_text (desired);
-			 }
-
-		 } else {
-			 sample_rate_combo.set_sensitive (false);
-		 }
-
-		 /* buffer sizes */
-
-		 vector<uint32_t> bs;
-
-		 if (_have_control) {
-			 bs = backend->available_buffer_sizes(device_name);
-		 } else if (backend->can_change_buffer_size_when_running()) {
-			 bs.push_back (8);
-			 bs.push_back (16);
-			 bs.push_back (32);
-			 bs.push_back (64);
-			 bs.push_back (128);
-			 bs.push_back (256);
-			 bs.push_back (512);
-			 bs.push_back (1024);
-			 bs.push_back (2048);
-			 bs.push_back (4096);
-			 bs.push_back (8192);
-		 }
-		 s.clear ();
-		 for (vector<uint32_t>::const_iterator x = bs.begin(); x != bs.end(); ++x) {
-			 s.push_back (bufsize_as_string (*x));
-		 }
-
-		 if (!s.empty()) {
-			 buffer_size_combo.set_sensitive (true);
-			 set_popdown_strings (buffer_size_combo, s);
-
-			 buffer_size_combo.set_active_text (bufsize_as_string (backend->default_buffer_size()));
-			 show_buffer_duration ();
-		 } else {
-			 buffer_size_combo.set_sensitive (false);
-		 }
-
-		 /* XXX theoretically need to set min + max channel counts here
-		  */
-
-		 manage_control_app_sensitivity ();
-	 }
-
-	 /* pick up any saved state for this device */
-
-	 if (!ignore_changes) {
-		 maybe_display_saved_state ();
-	 }
- }
-
- string
- EngineControl::bufsize_as_string (uint32_t sz)
- {
-	 /* Translators: "samples" is always plural here, so no
-	    need for plural+singular forms.
+		/* sample rates */
+
+		string desired;
+
+		vector<float> sr;
+
+		if (_have_control) {
+			sr = backend->available_sample_rates (device_name);
+		} else {
+
+			sr.push_back (8000.0f);
+			sr.push_back (16000.0f);
+			sr.push_back (32000.0f);
+			sr.push_back (44100.0f);
+			sr.push_back (48000.0f);
+			sr.push_back (88200.0f);
+			sr.push_back (96000.0f);
+			sr.push_back (192000.0f);
+			sr.push_back (384000.0f);
+		}
+
+		for (vector<float>::const_iterator x = sr.begin(); x != sr.end(); ++x) {
+			s.push_back (rate_as_string (*x));
+			if (*x == _desired_sample_rate) {
+				desired = s.back();
+			}
+		}
+
+		if (!s.empty()) {
+			sample_rate_combo.set_sensitive (true);
+			set_popdown_strings (sample_rate_combo, s);
+
+			if (desired.empty()) {
+				sample_rate_combo.set_active_text (rate_as_string (backend->default_sample_rate()));
+			} else {
+				sample_rate_combo.set_active_text (desired);
+			}
+
+		} else {
+			sample_rate_combo.set_sensitive (false);
+		}
+
+		/* buffer sizes */
+
+		vector<uint32_t> bs;
+
+		if (_have_control) {
+			bs = backend->available_buffer_sizes (device_name);
+		} else if (backend->can_change_buffer_size_when_running()) {
+			bs.push_back (8);
+			bs.push_back (16);
+			bs.push_back (32);
+			bs.push_back (64);
+			bs.push_back (128);
+			bs.push_back (256);
+			bs.push_back (512);
+			bs.push_back (1024);
+			bs.push_back (2048);
+			bs.push_back (4096);
+			bs.push_back (8192);
+		}
+		s.clear ();
+		for (vector<uint32_t>::const_iterator x = bs.begin(); x != bs.end(); ++x) {
+			s.push_back (bufsize_as_string (*x));
+		}
+
+		if (!s.empty()) {
+			buffer_size_combo.set_sensitive (true);
+			set_popdown_strings (buffer_size_combo, s);
+
+			buffer_size_combo.set_active_text (bufsize_as_string (backend->default_buffer_size()));
+			show_buffer_duration ();
+		} else {
+			buffer_size_combo.set_sensitive (false);
+		}
+
+		/* XXX theoretically need to set min + max channel counts here
+		*/
+
+		manage_control_app_sensitivity ();
+	}
+
+	/* pick up any saved state for this device */
+
+	if (!ignore_changes) {
+		maybe_display_saved_state ();
+	}
+}
+
+string
+EngineControl::bufsize_as_string (uint32_t sz)
+{
+	/* Translators: "samples" is always plural here, so no
+	   need for plural+singular forms.
 	 */
-	 char buf[32];
-	 snprintf (buf, sizeof (buf), _("%u samples"), sz);
-	 return buf;
- }
-
- void 
- EngineControl::sample_rate_changed ()
- {
-	 /* reset the strings for buffer size to show the correct msec value
-	    (reflecting the new sample rate).
+	char buf[32];
+	snprintf (buf, sizeof (buf), _("%u samples"), sz);
+	return buf;
+}
+
+void
+EngineControl::sample_rate_changed ()
+{
+	/* reset the strings for buffer size to show the correct msec value
+	   (reflecting the new sample rate).
 	 */
 
-	 show_buffer_duration ();
-	 if (!ignore_changes) {
-		 save_state ();
-	 }
+	show_buffer_duration ();
+	if (!ignore_changes) {
+		save_state ();
+	}
 
- }
+}
 
- void 
- EngineControl::buffer_size_changed ()
- {
-	 show_buffer_duration ();
-	 if (!ignore_changes) {
-		 save_state ();
-	 }
- }
+void
+EngineControl::buffer_size_changed ()
+{
+	show_buffer_duration ();
+	if (!ignore_changes) {
+		save_state ();
+	}
+}
 
- void
- EngineControl::show_buffer_duration ()
- {
+void
+EngineControl::show_buffer_duration ()
+{
 
-	 /* buffer sizes  - convert from just samples to samples + msecs for
-	  * the displayed string
-	  */
+	/* buffer sizes  - convert from just samples to samples + msecs for
+	 * the displayed string
+	 */
 
-	 string bs_text = buffer_size_combo.get_active_text ();
-	 uint32_t samples = atoi (bs_text); /* will ignore trailing text */
-	 uint32_t rate = get_rate();
+	string bs_text = buffer_size_combo.get_active_text ();
+	uint32_t samples = atoi (bs_text); /* will ignore trailing text */
+	uint32_t rate = get_rate();
 
-	 /* Translators: "msecs" is ALWAYS plural here, so we do not
-	    need singular form as well.
+	/* Translators: "msecs" is ALWAYS plural here, so we do not
+	   need singular form as well.
 	 */
-	 /* Developers: note the hard-coding of a double buffered model
-	    in the (2 * samples) computation of latency. we always start
-	    the audiobackend in this configuration.
+	/* Developers: note the hard-coding of a double buffered model
+	   in the (2 * samples) computation of latency. we always start
+	   the audiobackend in this configuration.
 	 */
-	 char buf[32];
-	 snprintf (buf, sizeof (buf), _("(%.1f msecs)"), (2 * samples) / (rate/1000.0));
-	 buffer_size_duration_label.set_text (buf);
- }
-
- void
- EngineControl::midi_option_changed ()
- {
-	 if (!ignore_changes) {
-		 save_state ();
-	 }
- }
-
- void
- EngineControl::parameter_changed ()
- {
-	 if (!ignore_changes) {
-		 save_state ();
-	 }
- }
-
- EngineControl::State*
- EngineControl::get_matching_state (const string& backend,
-				    const string& driver,
-				    const string& device)
- {
-	 for (StateList::iterator i = states.begin(); i != states.end(); ++i) {
-		 if ((*i).backend == backend &&
-		     (*i).driver == driver &&
-		     (*i).device == device) {
-			 return &(*i);
-		 }
-	 }
-	 return 0;
- }
-
- EngineControl::State*
- EngineControl::get_saved_state_for_currently_displayed_backend_and_device ()
- {
-	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
-
-	 if (backend) {
-		 return get_matching_state (backend_combo.get_active_text(),
-					    (backend->requires_driver_selection() ? (std::string) driver_combo.get_active_text() : string()),
-					    device_combo.get_active_text());
-	 }
-
-
-	 return get_matching_state (backend_combo.get_active_text(),
-				    string(),
-				    device_combo.get_active_text());
- }
-
- EngineControl::State*
- EngineControl::save_state ()
- {
-	 if (!_have_control) {
-		 return 0;
-	 }
-
-	 bool existing = true;
-	 State* state = get_saved_state_for_currently_displayed_backend_and_device ();
-
-	 if (!state) {
-		 existing = false;
-		 state = new State;
-	 }
-
-	 store_state (*state);
-
-	 if (!existing) {
-		 states.push_back (*state);
-	 }
-
-	 return state;
- }
-
- void
- EngineControl::store_state (State& state)
- {
-	 state.backend = get_backend ();
-	 state.driver = get_driver ();
-	 state.device = get_device_name ();
-	 state.sample_rate = get_rate ();
-	 state.buffer_size = get_buffer_size ();
-	 state.input_latency = get_input_latency ();
-	 state.output_latency = get_output_latency ();
-	 state.input_channels = get_input_channels ();
-	 state.output_channels = get_output_channels ();
-	 state.midi_option = get_midi_option ();
- }
-
- void
- EngineControl::maybe_display_saved_state ()
- {
-	 if (!_have_control) {
-		 return;
-	 }
-
-	 State* state = get_saved_state_for_currently_displayed_backend_and_device ();
-
-	 if (state) {
-		 PBD::Unwinder<uint32_t> protect_ignore_changes (ignore_changes, ignore_changes + 1);
-
-		 if (!_desired_sample_rate) {
-			 sample_rate_combo.set_active_text (rate_as_string (state->sample_rate));
-		 }
-		 buffer_size_combo.set_active_text (bufsize_as_string (state->buffer_size));
-		 /* call this explicitly because we're ignoring changes to
-		    the controls at this point.
+	char buf[32];
+	snprintf (buf, sizeof (buf), _("(%.1f msecs)"), (2 * samples) / (rate/1000.0));
+	buffer_size_duration_label.set_text (buf);
+}
+
+void
+EngineControl::midi_option_changed ()
+{
+	boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
+	assert (backend);
+
+	backend->set_midi_option (get_midi_option());
+
+	vector<ARDOUR::AudioBackend::DeviceStatus> midi_devices = backend->enumerate_midi_devices();
+
+	//_midi_devices.clear(); // TODO merge with state-saved settings..
+	_can_set_midi_latencies = backend->can_set_systemic_midi_latencies();
+	std::vector<MidiDeviceSettings> new_devices;
+
+	for (vector<ARDOUR::AudioBackend::DeviceStatus>::const_iterator i = midi_devices.begin(); i != midi_devices.end(); ++i) {
+		MidiDeviceSettings mds = find_midi_device (i->name);
+		if (i->available && !mds) {
+			uint32_t input_latency = 0;
+			uint32_t output_latency = 0;
+			if (_can_set_midi_latencies) {
+				input_latency = backend->systemic_midi_input_latency (i->name);
+				output_latency = backend->systemic_midi_output_latency (i->name);
+			}
+			bool enabled = backend->midi_device_enabled (i->name);
+			MidiDeviceSettings ptr (new MidiDeviceSetting (i->name, enabled, input_latency, output_latency));
+			new_devices.push_back (ptr);
+		} else if (i->available) {
+			new_devices.push_back (mds);
+		}
+	}
+	_midi_devices = new_devices;
+
+	if (_midi_devices.empty()) {
+		midi_devices_button.set_sensitive (false);
+	} else {
+		midi_devices_button.set_sensitive (true);
+	}
+
+	if (!ignore_changes) {
+		save_state ();
+	}
+}
+
+void
+EngineControl::parameter_changed ()
+{
+	if (!ignore_changes) {
+		save_state ();
+	}
+}
+
+EngineControl::State*
+EngineControl::get_matching_state (
+		const string& backend,
+		const string& driver,
+		const string& device)
+{
+	for (StateList::iterator i = states.begin(); i != states.end(); ++i) {
+		if ((*i).backend == backend &&
+				(*i).driver == driver &&
+				(*i).device == device) {
+			return &(*i);
+		}
+	}
+	return 0;
+}
+
+EngineControl::State*
+EngineControl::get_saved_state_for_currently_displayed_backend_and_device ()
+{
+	boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
+
+	if (backend) {
+		return get_matching_state (backend_combo.get_active_text(),
+				(backend->requires_driver_selection() ? (std::string) driver_combo.get_active_text() : string()),
+				device_combo.get_active_text());
+	}
+
+
+	return get_matching_state (backend_combo.get_active_text(),
+			string(),
+			device_combo.get_active_text());
+}
+
+EngineControl::State*
+EngineControl::save_state ()
+{
+	if (!_have_control) {
+		return 0;
+	}
+
+	bool existing = true;
+	State* state = get_saved_state_for_currently_displayed_backend_and_device ();
+
+	if (!state) {
+		existing = false;
+		state = new State;
+	}
+
+	store_state (*state);
+
+	if (!existing) {
+		states.push_back (*state);
+	}
+
+	return state;
+}
+
+void
+EngineControl::store_state (State& state)
+{
+	state.backend = get_backend ();
+	state.driver = get_driver ();
+	state.device = get_device_name ();
+	state.sample_rate = get_rate ();
+	state.buffer_size = get_buffer_size ();
+	state.input_latency = get_input_latency ();
+	state.output_latency = get_output_latency ();
+	state.input_channels = get_input_channels ();
+	state.output_channels = get_output_channels ();
+	state.midi_option = get_midi_option ();
+	state.midi_devices = _midi_devices;
+}
+
+void
+EngineControl::maybe_display_saved_state ()
+{
+	if (!_have_control) {
+		return;
+	}
+
+	State* state = get_saved_state_for_currently_displayed_backend_and_device ();
+
+	if (state) {
+		PBD::Unwinder<uint32_t> protect_ignore_changes (ignore_changes, ignore_changes + 1);
+
+		if (!_desired_sample_rate) {
+			sample_rate_combo.set_active_text (rate_as_string (state->sample_rate));
+		}
+		buffer_size_combo.set_active_text (bufsize_as_string (state->buffer_size));
+		/* call this explicitly because we're ignoring changes to
+		   the controls at this point.
 		 */
-		 show_buffer_duration ();
-		 input_latency.set_value (state->input_latency);
-		 output_latency.set_value (state->output_latency);
-
-		 if (!state->midi_option.empty()) {
-			 midi_option_combo.set_active_text (state->midi_option);
-		 }
-	 }
- }
+		show_buffer_duration ();
+		input_latency.set_value (state->input_latency);
+		output_latency.set_value (state->output_latency);
+
+		if (!state->midi_option.empty()) {
+			midi_option_combo.set_active_text (state->midi_option);
+			_midi_devices = state->midi_devices;
+		}
+	}
+}
+
+XMLNode&
+EngineControl::get_state ()
+{
+	XMLNode* root = new XMLNode ("AudioMIDISetup");
+	std::string path;
+
+	if (!states.empty()) {
+		XMLNode* state_nodes = new XMLNode ("EngineStates");
+
+		for (StateList::const_iterator i = states.begin(); i != states.end(); ++i) {
+
+			XMLNode* node = new XMLNode ("State");
+
+			node->add_property ("backend", (*i).backend);
+			node->add_property ("driver", (*i).driver);
+			node->add_property ("device", (*i).device);
+			node->add_property ("sample-rate", (*i).sample_rate);
+			node->add_property ("buffer-size", (*i).buffer_size);
+			node->add_property ("input-latency", (*i).input_latency);
+			node->add_property ("output-latency", (*i).output_latency);
+			node->add_property ("input-channels", (*i).input_channels);
+			node->add_property ("output-channels", (*i).output_channels);
+			node->add_property ("active", (*i).active ? "yes" : "no");
+			node->add_property ("midi-option", (*i).midi_option);
+
+			XMLNode* midi_devices = new XMLNode ("MIDIDevices");
+			for (std::vector<MidiDeviceSettings>::const_iterator p = (*i).midi_devices.begin(); p != (*i).midi_devices.end(); ++p) {
+				XMLNode* midi_device_stuff = new XMLNode ("MIDIDevice");
+				midi_device_stuff->add_property (X_("name"), (*p)->name);
+				midi_device_stuff->add_property (X_("enabled"), (*p)->enabled);
+				midi_device_stuff->add_property (X_("input-latency"), (*p)->input_latency);
+				midi_device_stuff->add_property (X_("output-latency"), (*p)->output_latency);
+				midi_devices->add_child_nocopy (*midi_device_stuff);
+			}
+			node->add_child_nocopy (*midi_devices);
+
+			state_nodes->add_child_nocopy (*node);
+		}
+
+		root->add_child_nocopy (*state_nodes);
+	}
+
+	return *root;
+}
+
+void
+EngineControl::set_state (const XMLNode& root)
+{
+	XMLNodeList          clist, cclist;
+	XMLNodeConstIterator citer, cciter;
+	XMLNode* child;
+	XMLNode* grandchild;
+	XMLProperty* prop = NULL;
+
+	if (root.name() != "AudioMIDISetup") {
+		return;
+	}
+
+	clist = root.children();
+
+	states.clear ();
 
- XMLNode&
- EngineControl::get_state ()
- {
-	 XMLNode* root = new XMLNode ("AudioMIDISetup");
-	 std::string path;
-
-	 if (!states.empty()) {
-		 XMLNode* state_nodes = new XMLNode ("EngineStates");
-
-		 for (StateList::const_iterator i = states.begin(); i != states.end(); ++i) {
-
-			 XMLNode* node = new XMLNode ("State");
-
-			 node->add_property ("backend", (*i).backend);
-			 node->add_property ("driver", (*i).driver);
-			 node->add_property ("device", (*i).device);
-			 node->add_property ("sample-rate", (*i).sample_rate);
-			 node->add_property ("buffer-size", (*i).buffer_size);
-			 node->add_property ("input-latency", (*i).input_latency);
-			 node->add_property ("output-latency", (*i).output_latency);
-			 node->add_property ("input-channels", (*i).input_channels);
-			 node->add_property ("output-channels", (*i).output_channels);
-			 node->add_property ("active", (*i).active ? "yes" : "no");
-			 node->add_property ("midi-option", (*i).midi_option);
-
-			 state_nodes->add_child_nocopy (*node);
-		 }
-
-		 root->add_child_nocopy (*state_nodes);
-	 }
-
-	 return *root;
- }
-
- void
- EngineControl::set_state (const XMLNode& root)
- {
-	 XMLNodeList          clist, cclist;
-	 XMLNodeConstIterator citer, cciter;
-	 XMLNode* child;
-	 XMLNode* grandchild;
-	 XMLProperty* prop = NULL;
-
-	 if (root.name() != "AudioMIDISetup") {
-		 return;
-	 }
-
-	 clist = root.children();
-
-	 states.clear ();
-
-	 for (citer = clist.begin(); citer != clist.end(); ++citer) {
-
-		 child = *citer;
-
-		 if (child->name() != "EngineStates") {
-			 continue;
-		 }
-
-		 cclist = child->children();
-
-		 for (cciter = cclist.begin(); cciter != cclist.end(); ++cciter) {
-			 State state;
-
-			 grandchild = *cciter;
-
-			 if (grandchild->name() != "State") {
-				 continue;
-			 }
-
-			 if ((prop = grandchild->property ("backend")) == 0) {
-				 continue;
-			 }
-			 state.backend = prop->value ();
-
-			 if ((prop = grandchild->property ("driver")) == 0) {
-				 continue;
-			 }
-			 state.driver = prop->value ();
-
-			 if ((prop = grandchild->property ("device")) == 0) {
-				 continue;
-			 }
-			 state.device = prop->value ();
-
-			 if ((prop = grandchild->property ("sample-rate")) == 0) {
-				 continue;
-			 }
-			 state.sample_rate = atof (prop->value ());
-
-			 if ((prop = grandchild->property ("buffer-size")) == 0) {
-				 continue;
-			 }
-			 state.buffer_size = atoi (prop->value ());
-
-			 if ((prop = grandchild->property ("input-latency")) == 0) {
-				 continue;
-			 }
-			 state.input_latency = atoi (prop->value ());
-
-			 if ((prop = grandchild->property ("output-latency")) == 0) {
-				 continue;
-			 }
-			 state.output_latency = atoi (prop->value ());
-
-			 if ((prop = grandchild->property ("input-channels")) == 0) {
-				 continue;
-			 }
-			 state.input_channels = atoi (prop->value ());
-
-			 if ((prop = grandchild->property ("output-channels")) == 0) {
-				 continue;
-			 }
-			 state.output_channels = atoi (prop->value ());
-
-			 if ((prop = grandchild->property ("active")) == 0) {
-				 continue;
-			 }
-			 state.active = string_is_affirmative (prop->value ());
-
-			 if ((prop = grandchild->property ("midi-option")) == 0) {
-				 continue;
-			 }
-			 state.midi_option = prop->value ();
-
-			 states.push_back (state);
-		 }
-	 }
-
-	 /* now see if there was an active state and switch the setup to it */
-
-	 for (StateList::const_iterator i = states.begin(); i != states.end(); ++i) {
-
-		 if ((*i).active) {
-			 ignore_changes++;
-			 backend_combo.set_active_text ((*i).backend);
-			 driver_combo.set_active_text ((*i).driver);
-			 device_combo.set_active_text ((*i).device);
-			 sample_rate_combo.set_active_text (rate_as_string ((*i).sample_rate));
-			 buffer_size_combo.set_active_text (bufsize_as_string ((*i).buffer_size));
-			 input_latency.set_value ((*i).input_latency);
-			 output_latency.set_value ((*i).output_latency);
-			 midi_option_combo.set_active_text ((*i).midi_option);
-			 ignore_changes--;
-			 break;
-		 }
-	 }
- }
-
- int
- EngineControl::push_state_to_backend (bool start)
- {
-	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
-
-	 if (!backend) {
-		 return 0;
-	 }
-
-	 /* figure out what is going to change */
-
-	 bool restart_required = false;
-	 bool was_running = ARDOUR::AudioEngine::instance()->running();
-	 bool change_driver = false;
-	 bool change_device = false;
-	 bool change_rate = false;
-	 bool change_bufsize = false;
-	 bool change_latency = false;
-	 bool change_channels = false;
-	 bool change_midi = false;
-
-	 uint32_t ochan = get_output_channels ();
-	 uint32_t ichan = get_input_channels ();
-
-	 if (_have_control) {
-
-		 if (started_at_least_once) {
-
-			 /* we can control the backend */
-
-			 if (backend->requires_driver_selection()) {
-				 if (get_driver() != backend->driver_name()) {
-					 change_driver = true;
-				 }
-			 }
-
-			 if (get_device_name() != backend->device_name()) {
-				 change_device = true;
-			 }
-
-			 if (get_rate() != backend->sample_rate()) {
-				 change_rate = true;
-			 }
-
-			 if (get_buffer_size() != backend->buffer_size()) {
-				 change_bufsize = true;
-			 }
-
-			 if (get_midi_option() != backend->midi_option()) {
-				 change_midi = true;
-			 }
-
-			 /* zero-requested channels means "all available" */
-
-			 if (ichan == 0) {
-				 ichan = backend->input_channels();
-			 }
-
-			 if (ochan == 0) {
-				 ochan = backend->output_channels();
-			 }
-
-			 if (ichan != backend->input_channels()) {
-				 change_channels = true;
-			 }
-
-			 if (ochan != backend->output_channels()) {
-				 change_channels = true;
-			 }
-
-			 if (get_input_latency() != backend->systemic_input_latency() ||
-			     get_output_latency() != backend->systemic_output_latency()) {
-				 change_latency = true;
-			 }
-		 } else {
-			 /* backend never started, so we have to force a group
-			    of settings.
+	for (citer = clist.begin(); citer != clist.end(); ++citer) {
+
+		child = *citer;
+
+		if (child->name() != "EngineStates") {
+			continue;
+		}
+
+		cclist = child->children();
+
+		for (cciter = cclist.begin(); cciter != cclist.end(); ++cciter) {
+			State state;
+
+			grandchild = *cciter;
+
+			if (grandchild->name() != "State") {
+				continue;
+			}
+
+			if ((prop = grandchild->property ("backend")) == 0) {
+				continue;
+			}
+			state.backend = prop->value ();
+
+			if ((prop = grandchild->property ("driver")) == 0) {
+				continue;
+			}
+			state.driver = prop->value ();
+
+			if ((prop = grandchild->property ("device")) == 0) {
+				continue;
+			}
+			state.device = prop->value ();
+
+			if ((prop = grandchild->property ("sample-rate")) == 0) {
+				continue;
+			}
+			state.sample_rate = atof (prop->value ());
+
+			if ((prop = grandchild->property ("buffer-size")) == 0) {
+				continue;
+			}
+			state.buffer_size = atoi (prop->value ());
+
+			if ((prop = grandchild->property ("input-latency")) == 0) {
+				continue;
+			}
+			state.input_latency = atoi (prop->value ());
+
+			if ((prop = grandchild->property ("output-latency")) == 0) {
+				continue;
+			}
+			state.output_latency = atoi (prop->value ());
+
+			if ((prop = grandchild->property ("input-channels")) == 0) {
+				continue;
+			}
+			state.input_channels = atoi (prop->value ());
+
+			if ((prop = grandchild->property ("output-channels")) == 0) {
+				continue;
+			}
+			state.output_channels = atoi (prop->value ());
+
+			if ((prop = grandchild->property ("active")) == 0) {
+				continue;
+			}
+			state.active = string_is_affirmative (prop->value ());
+
+			if ((prop = grandchild->property ("midi-option")) == 0) {
+				continue;
+			}
+			state.midi_option = prop->value ();
+
+			state.midi_devices.clear();
+			XMLNode* midinode;
+			if ((midinode = find_named_node (*grandchild, "MIDIDevices")) != 0) {
+				const XMLNodeList mnc = midinode->children();
+				for (XMLNodeList::const_iterator n = mnc.begin(); n != mnc.end(); ++n) {
+					if ((*n)->property (X_("name")) == 0
+							|| (*n)->property (X_("enabled")) == 0
+							|| (*n)->property (X_("input-latency")) == 0
+							|| (*n)->property (X_("output-latency")) == 0
+						 ) {
+						continue;
+					}
+
+					MidiDeviceSettings ptr (new MidiDeviceSetting(
+								(*n)->property (X_("name"))->value (),
+								string_is_affirmative ((*n)->property (X_("enabled"))->value ()),
+								atoi ((*n)->property (X_("input-latency"))->value ()),
+								atoi ((*n)->property (X_("output-latency"))->value ())
+								));
+					state.midi_devices.push_back (ptr);
+				}
+			}
+
+			states.push_back (state);
+		}
+	}
+
+	/* now see if there was an active state and switch the setup to it */
+
+	for (StateList::const_iterator i = states.begin(); i != states.end(); ++i) {
+
+		if ((*i).active) {
+			ignore_changes++;
+			backend_combo.set_active_text ((*i).backend);
+			driver_combo.set_active_text ((*i).driver);
+			device_combo.set_active_text ((*i).device);
+			sample_rate_combo.set_active_text (rate_as_string ((*i).sample_rate));
+			buffer_size_combo.set_active_text (bufsize_as_string ((*i).buffer_size));
+			input_latency.set_value ((*i).input_latency);
+			output_latency.set_value ((*i).output_latency);
+			midi_option_combo.set_active_text ((*i).midi_option);
+			ignore_changes--;
+			break;
+		}
+	}
+}
+
+int
+EngineControl::push_state_to_backend (bool start)
+{
+	boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
+
+	if (!backend) {
+		return 0;
+	}
+
+	/* figure out what is going to change */
+
+	bool restart_required = false;
+	bool was_running = ARDOUR::AudioEngine::instance()->running();
+	bool change_driver = false;
+	bool change_device = false;
+	bool change_rate = false;
+	bool change_bufsize = false;
+	bool change_latency = false;
+	bool change_channels = false;
+	bool change_midi = false;
+
+	uint32_t ochan = get_output_channels ();
+	uint32_t ichan = get_input_channels ();
+
+	if (_have_control) {
+
+		if (started_at_least_once) {
+
+			/* we can control the backend */
+
+			if (backend->requires_driver_selection()) {
+				if (get_driver() != backend->driver_name()) {
+					change_driver = true;
+				}
+			}
+
+			if (get_device_name() != backend->device_name()) {
+				change_device = true;
+			}
+
+			if (get_rate() != backend->sample_rate()) {
+				change_rate = true;
+			}
+
+			if (get_buffer_size() != backend->buffer_size()) {
+				change_bufsize = true;
+			}
+
+			if (get_midi_option() != backend->midi_option()) {
+				change_midi = true;
+			}
+
+			/* zero-requested channels means "all available" */
+
+			if (ichan == 0) {
+				ichan = backend->input_channels();
+			}
+
+			if (ochan == 0) {
+				ochan = backend->output_channels();
+			}
+
+			if (ichan != backend->input_channels()) {
+				change_channels = true;
+			}
+
+			if (ochan != backend->output_channels()) {
+				change_channels = true;
+			}
+
+			if (get_input_latency() != backend->systemic_input_latency() ||
+					get_output_latency() != backend->systemic_output_latency()) {
+				change_latency = true;
+			}
+		} else {
+			/* backend never started, so we have to force a group
+			   of settings.
 			 */
-			 change_device = true;
-			 if (backend->requires_driver_selection()) {
-				 change_driver = true;
-			 }
-			 change_rate = true;
-			 change_bufsize = true;
-			 change_channels = true;
-			 change_latency = true;
-			 change_midi = true;
-		 }
-
-	 } else {
-
-		 /* we have no control over the backend, meaning that we can
-		  * only possibly change sample rate and buffer size.
-		  */
-
-
-		 if (get_rate() != backend->sample_rate()) {
-			 change_bufsize = true;
-		 }
-
-		 if (get_buffer_size() != backend->buffer_size()) {
-			 change_bufsize = true;
-		 }
-	 }
-
-	 if (!_have_control) {
-
-		 /* We do not have control over the backend, so the best we can
-		  * do is try to change the sample rate and/or bufsize and get
-		  * out of here.
-		  */
-
-		 if (change_rate && !backend->can_change_sample_rate_when_running()) {
-			 return 1;
-		 }
-
-		 if (change_bufsize && !backend->can_change_buffer_size_when_running()) {
-			 return 1;
-		 }
-
-		 if (change_rate) {
-			 backend->set_sample_rate (get_rate());
-		 }
-
-		 if (change_bufsize) {
-			 backend->set_buffer_size (get_buffer_size());
-		 }
-
-		 if (start) {
-			 if (ARDOUR::AudioEngine::instance()->start ()) {
-				 error << string_compose (_("Could not start backend engine %1"), backend->name()) << endmsg;
-				 return -1;
-			 }
-		 }
-
-		 post_push ();
-
-		 return 0;
-	 } 
-
-	 /* determine if we need to stop the backend before changing parameters */
-
-	 if (change_driver || change_device || change_channels || change_latency ||
-	     (change_rate && !backend->can_change_sample_rate_when_running()) ||
-	     change_midi ||
-	     (change_bufsize && !backend->can_change_buffer_size_when_running())) {
-		 restart_required = true;
-	 } else {
-		 restart_required = false;
-	 }
-
-	 if (was_running) {
-
-		 if (!change_driver && !change_device && !change_channels && !change_latency && !change_midi) {
-			 /* no changes in any parameters that absolutely require a
-			  * restart, so check those that might be changeable without a
-			  * restart
-			  */
-
-			 if (change_rate && !backend->can_change_sample_rate_when_running()) {
-				 /* can't do this while running ... */
-				 restart_required = true;
-			 }
-
-			 if (change_bufsize && !backend->can_change_buffer_size_when_running()) {
-				 /* can't do this while running ... */
-				 restart_required = true;
-			 }
-		 }
-	 }
-
-	 if (was_running) {
-		 if (restart_required) {
-			 if (ARDOUR_UI::instance()->disconnect_from_engine ()) {
-				 return -1;
-			 }
-		 }
-	 }
-
-
-	 if (change_driver && backend->set_driver (get_driver())) {
-		 error << string_compose (_("Cannot set driver to %1"), get_driver()) << endmsg;
-		 return -1;
-	 }
-	 if (change_device && backend->set_device_name (get_device_name())) {
-		 error << string_compose (_("Cannot set device name to %1"), get_device_name()) << endmsg;
-		 return -1;
-	 }
-	 if (change_rate && backend->set_sample_rate (get_rate())) {
-		 error << string_compose (_("Cannot set sample rate to %1"), get_rate()) << endmsg;
-		 return -1;
-	 }
-	 if (change_bufsize && backend->set_buffer_size (get_buffer_size())) {
-		 error << string_compose (_("Cannot set buffer size to %1"), get_buffer_size()) << endmsg;
-		 return -1;
-	 }
-
-	 if (change_channels || get_input_channels() == 0 || get_output_channels() == 0) {
-		 if (backend->set_input_channels (get_input_channels())) {
-			 error << string_compose (_("Cannot set input channels to %1"), get_input_channels()) << endmsg;
-			 return -1;
-		 }
-		 if (backend->set_output_channels (get_output_channels())) {
-			 error << string_compose (_("Cannot set output channels to %1"), get_output_channels()) << endmsg;
-			 return -1;
-		 }
-	 }
-	 if (change_latency) {
-		 if (backend->set_systemic_input_latency (get_input_latency())) {
-			 error << string_compose (_("Cannot set input latency to %1"), get_input_latency()) << endmsg;
-			 return -1;
-		 }
-		 if (backend->set_systemic_output_latency (get_output_latency())) {
-			 error << string_compose (_("Cannot set output latency to %1"), get_output_latency()) << endmsg;
-			 return -1;
-		 }
-	 }
-
-	 if (change_midi) {
-		 backend->set_midi_option (get_midi_option());
-	 }
-
-	 if (start || (was_running && restart_required)) {
-		 if (ARDOUR_UI::instance()->reconnect_to_engine()) {
-			 return -1;
-		 }
-	 }
-
-	 post_push ();
-
-	 return 0;
- }
-
- void
- EngineControl::post_push ()
- {
-	 /* get a pointer to the current state object, creating one if
-	  * necessary
-	  */
-
-	 if (_have_control) {
-		 State* state = get_saved_state_for_currently_displayed_backend_and_device ();
-
-		 if (!state) {
-			 state = save_state ();
-			 assert (state);
-		 }
-
-		 /* all off */
-
-		 for (StateList::iterator i = states.begin(); i != states.end(); ++i) {
-			 (*i).active = false;
-		 }
-
-		 /* mark this one active (to be used next time the dialog is
-		  * shown)
-		  */
-
-		 state->active = true;
-
-		 manage_control_app_sensitivity ();
-	 }
-
-	 /* schedule a redisplay of MIDI ports */
-
-	 Glib::signal_timeout().connect (sigc::bind_return (sigc::mem_fun (*this, &EngineControl::refresh_midi_display), false), 1000);
- }
-
-
- float
- EngineControl::get_rate () const
- {
-	 float r = atof (sample_rate_combo.get_active_text ());
-	 /* the string may have been translated with an abbreviation for
-	  * thousands, so use a crude heuristic to fix this.
-	  */
-	 if (r < 1000.0) {
-		 r *= 1000.0;
-	 }
-	 return r;
- }
-
-
- uint32_t
- EngineControl::get_buffer_size () const
- {
-	 string txt = buffer_size_combo.get_active_text ();
-	 uint32_t samples;
-
-	 if (sscanf (txt.c_str(), "%d", &samples) != 1) {
-		 throw exception ();
-	 }
-
-	 return samples;
- }
-
- string
- EngineControl::get_midi_option () const
- {
-	 return midi_option_combo.get_active_text();
- }
-
- uint32_t
- EngineControl::get_input_channels() const
- {
-	 return (uint32_t) input_channels_adjustment.get_value();
- }
-
- uint32_t
- EngineControl::get_output_channels() const
- {
-	 return (uint32_t) output_channels_adjustment.get_value();
- }
-
- uint32_t
- EngineControl::get_input_latency() const
- {
-	 return (uint32_t) input_latency_adjustment.get_value();
- }
-
- uint32_t
- EngineControl::get_output_latency() const
- {
-	 return (uint32_t) output_latency_adjustment.get_value();
- }
-
- string
- EngineControl::get_backend () const
- {
-	 return backend_combo.get_active_text ();
- }
-
- string
- EngineControl::get_driver () const
- {
-	 return driver_combo.get_active_text ();
- }
-
- string
- EngineControl::get_device_name () const
- {
-	 return device_combo.get_active_text ();
- }
-
- void
- EngineControl::control_app_button_clicked ()
- {
-	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
-
-	 if (!backend) {
-		 return;
-	 }
-
-	 backend->launch_control_app ();
- }
-
- void
- EngineControl::manage_control_app_sensitivity ()
- {
-	 boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
-
-	 if (!backend) {
-		 return;
-	 }
-
-	 string appname = backend->control_app_name();
-
-	 if (appname.empty()) {
-		 control_app_button.set_sensitive (false);
-	 } else {
-		 control_app_button.set_sensitive (true);
-	 }
- }
-
- void
- EngineControl::set_desired_sample_rate (uint32_t sr)
- {
-	 _desired_sample_rate = sr;
-	 device_changed ();
- }
-
- void
- EngineControl::on_switch_page (GtkNotebookPage*, guint page_num)
- {
-	 if (page_num == 0) {
-		 cancel_button->set_sensitive (true);
-		 ok_button->set_sensitive (true);
-		 apply_button->set_sensitive (true);
-	 } else {
-		 cancel_button->set_sensitive (false);
-		 ok_button->set_sensitive (false);
-		 apply_button->set_sensitive (false);
-	 }
-
-	 if (page_num == midi_tab) {
-		 /* MIDI tab */
-		 refresh_midi_display ();
-	 }
-
-	 if (page_num == latency_tab) {
-		 /* latency tab */
-
-		 if (!ARDOUR::AudioEngine::instance()->running()) {
-
-			 PBD::Unwinder<uint32_t> protect_ignore_changes (ignore_changes, ignore_changes + 1);
-
-			 /* save any existing latency values */
-
-			 uint32_t il = (uint32_t) input_latency.get_value ();
-			 uint32_t ol = (uint32_t) input_latency.get_value ();
-
-			 /* reset to zero so that our new test instance
-			    will be clean of any existing latency measures.
+			change_device = true;
+			if (backend->requires_driver_selection()) {
+				change_driver = true;
+			}
+			change_rate = true;
+			change_bufsize = true;
+			change_channels = true;
+			change_latency = true;
+			change_midi = true;
+		}
+
+	} else {
+
+		/* we have no control over the backend, meaning that we can
+		 * only possibly change sample rate and buffer size.
+		 */
+
+
+		if (get_rate() != backend->sample_rate()) {
+			change_bufsize = true;
+		}
+
+		if (get_buffer_size() != backend->buffer_size()) {
+			change_bufsize = true;
+		}
+	}
+
+	if (!_have_control) {
+
+		/* We do not have control over the backend, so the best we can
+		 * do is try to change the sample rate and/or bufsize and get
+		 * out of here.
+		 */
+
+		if (change_rate && !backend->can_change_sample_rate_when_running()) {
+			return 1;
+		}
+
+		if (change_bufsize && !backend->can_change_buffer_size_when_running()) {
+			return 1;
+		}
+
+		if (change_rate) {
+			backend->set_sample_rate (get_rate());
+		}
+
+		if (change_bufsize) {
+			backend->set_buffer_size (get_buffer_size());
+		}
+
+		if (start) {
+			if (ARDOUR::AudioEngine::instance()->start ()) {
+				error << string_compose (_("Could not start backend engine %1"), backend->name()) << endmsg;
+				return -1;
+			}
+		}
+
+		post_push ();
+
+		return 0;
+	}
+
+	/* determine if we need to stop the backend before changing parameters */
+
+	if (change_driver || change_device || change_channels || change_latency ||
+			(change_rate && !backend->can_change_sample_rate_when_running()) ||
+			change_midi ||
+			(change_bufsize && !backend->can_change_buffer_size_when_running())) {
+		restart_required = true;
+	} else {
+		restart_required = false;
+	}
+
+	if (was_running) {
+
+		if (!change_driver && !change_device && !change_channels && !change_latency && !change_midi) {
+			/* no changes in any parameters that absolutely require a
+			 * restart, so check those that might be changeable without a
+			 * restart
 			 */
 
-			 input_latency.set_value (0);
-			 output_latency.set_value (0);
+			if (change_rate && !backend->can_change_sample_rate_when_running()) {
+				/* can't do this while running ... */
+				restart_required = true;
+			}
+
+			if (change_bufsize && !backend->can_change_buffer_size_when_running()) {
+				/* can't do this while running ... */
+				restart_required = true;
+			}
+		}
+	}
+
+	if (was_running) {
+		if (restart_required) {
+			if (ARDOUR_UI::instance()->disconnect_from_engine ()) {
+				return -1;
+			}
+		}
+	}
+
+
+	if (change_driver && backend->set_driver (get_driver())) {
+		error << string_compose (_("Cannot set driver to %1"), get_driver()) << endmsg;
+		return -1;
+	}
+	if (change_device && backend->set_device_name (get_device_name())) {
+		error << string_compose (_("Cannot set device name to %1"), get_device_name()) << endmsg;
+		return -1;
+	}
+	if (change_rate && backend->set_sample_rate (get_rate())) {
+		error << string_compose (_("Cannot set sample rate to %1"), get_rate()) << endmsg;
+		return -1;
+	}
+	if (change_bufsize && backend->set_buffer_size (get_buffer_size())) {
+		error << string_compose (_("Cannot set buffer size to %1"), get_buffer_size()) << endmsg;
+		return -1;
+	}
+
+	if (change_channels || get_input_channels() == 0 || get_output_channels() == 0) {
+		if (backend->set_input_channels (get_input_channels())) {
+			error << string_compose (_("Cannot set input channels to %1"), get_input_channels()) << endmsg;
+			return -1;
+		}
+		if (backend->set_output_channels (get_output_channels())) {
+			error << string_compose (_("Cannot set output channels to %1"), get_output_channels()) << endmsg;
+			return -1;
+		}
+	}
+	if (change_latency) {
+		if (backend->set_systemic_input_latency (get_input_latency())) {
+			error << string_compose (_("Cannot set input latency to %1"), get_input_latency()) << endmsg;
+			return -1;
+		}
+		if (backend->set_systemic_output_latency (get_output_latency())) {
+			error << string_compose (_("Cannot set output latency to %1"), get_output_latency()) << endmsg;
+			return -1;
+		}
+	}
+
+	if (change_midi) {
+		backend->set_midi_option (get_midi_option());
+	}
+
+	if (1 /* TODO */) {
+		for (vector<MidiDeviceSettings>::const_iterator p = _midi_devices.begin(); p != _midi_devices.end(); ++p) {
+			if (_measure_midi) {
+				if (*p == _measure_midi) {
+					backend->set_midi_device_enabled ((*p)->name, true);
+				} else {
+					backend->set_midi_device_enabled ((*p)->name, false);
+				}
+				continue;
+			}
+			backend->set_midi_device_enabled ((*p)->name, (*p)->enabled);
+			if (backend->can_set_systemic_midi_latencies()) {
+				backend->set_systemic_midi_input_latency ((*p)->name, (*p)->input_latency);
+				backend->set_systemic_midi_output_latency ((*p)->name, (*p)->output_latency);
+			}
+		}
+	}
+
+	if (start || (was_running && restart_required)) {
+		if (ARDOUR_UI::instance()->reconnect_to_engine()) {
+			return -1;
+		}
+	}
+
+	post_push ();
+
+	return 0;
+}
+
+void
+EngineControl::post_push ()
+{
+	/* get a pointer to the current state object, creating one if
+	 * necessary
+	 */
+
+	if (_have_control) {
+		State* state = get_saved_state_for_currently_displayed_backend_and_device ();
+
+		if (!state) {
+			state = save_state ();
+			assert (state);
+		}
+
+		/* all off */
+
+		for (StateList::iterator i = states.begin(); i != states.end(); ++i) {
+			(*i).active = false;
+		}
+
+		/* mark this one active (to be used next time the dialog is
+		 * shown)
+		 */
+
+		state->active = true;
+
+		manage_control_app_sensitivity ();
+	}
+
+	/* schedule a redisplay of MIDI ports */
+	//Glib::signal_timeout().connect (sigc::bind_return (sigc::mem_fun (*this, &EngineControl::refresh_midi_display), false), 1000);
+}
+
+
+float
+EngineControl::get_rate () const
+{
+	float r = atof (sample_rate_combo.get_active_text ());
+	/* the string may have been translated with an abbreviation for
+	 * thousands, so use a crude heuristic to fix this.
+	 */
+	if (r < 1000.0) {
+		r *= 1000.0;
+	}
+	return r;
+}
+
+
+uint32_t
+EngineControl::get_buffer_size () const
+{
+	string txt = buffer_size_combo.get_active_text ();
+	uint32_t samples;
+
+	if (sscanf (txt.c_str(), "%d", &samples) != 1) {
+		throw exception ();
+	}
+
+	return samples;
+}
+
+string
+EngineControl::get_midi_option () const
+{
+	return midi_option_combo.get_active_text();
+}
+
+uint32_t
+EngineControl::get_input_channels() const
+{
+	return (uint32_t) input_channels_adjustment.get_value();
+}
+
+uint32_t
+EngineControl::get_output_channels() const
+{
+	return (uint32_t) output_channels_adjustment.get_value();
+}
+
+uint32_t
+EngineControl::get_input_latency() const
+{
+	return (uint32_t) input_latency_adjustment.get_value();
+}
+
+uint32_t
+EngineControl::get_output_latency() const
+{
+	return (uint32_t) output_latency_adjustment.get_value();
+}
 
-			 push_state_to_backend(false);
+string
+EngineControl::get_backend () const
+{
+	return backend_combo.get_active_text ();
+}
 
-			 /* reset control */
+string
+EngineControl::get_driver () const
+{
+	return driver_combo.get_active_text ();
+}
+
+string
+EngineControl::get_device_name () const
+{
+	return device_combo.get_active_text ();
+}
 
-			 input_latency.set_value (il);
-			 output_latency.set_value (ol);
+void
+EngineControl::control_app_button_clicked ()
+{
+	boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
 
-		 } 
+	if (!backend) {
+		return;
+	}
 
-		 if (ARDOUR::AudioEngine::instance()->prepare_for_latency_measurement()) {
-			 disable_latency_tab ();
-		 }
+	backend->launch_control_app ();
+}
 
-		 enable_latency_tab ();
+void
+EngineControl::manage_control_app_sensitivity ()
+{
+	boost::shared_ptr<ARDOUR::AudioBackend> backend = ARDOUR::AudioEngine::instance()->current_backend();
 
-	 } else {
-		 if (lm_running) {
-			 ARDOUR::AudioEngine::instance()->stop_latency_detection();
-		 }
-	 }
- }
+	if (!backend) {
+		return;
+	}
+
+	string appname = backend->control_app_name();
+
+	if (appname.empty()) {
+		control_app_button.set_sensitive (false);
+	} else {
+		control_app_button.set_sensitive (true);
+	}
+}
+
+void
+EngineControl::set_desired_sample_rate (uint32_t sr)
+{
+	_desired_sample_rate = sr;
+	device_changed ();
+}
+
+void
+EngineControl::on_switch_page (GtkNotebookPage*, guint page_num)
+{
+	if (page_num == 0) {
+		cancel_button->set_sensitive (true);
+		ok_button->set_sensitive (true);
+		apply_button->set_sensitive (true);
+		_measure_midi.reset();
+	} else {
+		cancel_button->set_sensitive (false);
+		ok_button->set_sensitive (false);
+		apply_button->set_sensitive (false);
+	}
+
+	if (page_num == midi_tab) {
+		/* MIDI tab */
+		refresh_midi_display ();
+	}
 
- /* latency measurement */
+	if (page_num == latency_tab) {
+		/* latency tab */
+
+		if (ARDOUR::AudioEngine::instance()->running()) {
+			// TODO - mark as 'stopped for latency
+			ARDOUR_UI::instance()->disconnect_from_engine ();
+		}
+
+		{
+			PBD::Unwinder<uint32_t> protect_ignore_changes (ignore_changes, ignore_changes + 1);
+
+			/* save any existing latency values */
+
+			uint32_t il = (uint32_t) input_latency.get_value ();
+			uint32_t ol = (uint32_t) input_latency.get_value ();
+
+			/* reset to zero so that our new test instance
+			   will be clean of any existing latency measures.
+
+			   NB. this should really be done by the backend
+			   when stated for latency measurement.
+			*/
+
+			input_latency.set_value (0);
+			output_latency.set_value (0);
+
+			push_state_to_backend (false);
+
+			/* reset control */
+
+			input_latency.set_value (il);
+			output_latency.set_value (ol);
+
+		}
+		// This should be done in push_state_to_backend()
+		if (ARDOUR::AudioEngine::instance()->prepare_for_latency_measurement()) {
+			disable_latency_tab ();
+		}
+
+		enable_latency_tab ();
+
+	} else {
+		if (lm_running) {
+			ARDOUR::AudioEngine::instance()->stop_latency_detection();
+		}
+	}
+}
+
+/* latency measurement */
 
 bool
 EngineControl::check_audio_latency_measurement ()
@@ -1752,7 +1886,7 @@ EngineControl::check_midi_latency_measurement ()
 
 	if (solid) {
 		end_latency_detection ();
-		lm_use_button.set_sensitive (false); // XXX TODO
+		lm_use_button.set_sensitive (true);
 		have_lm_results = true;
 	}
 
@@ -1767,7 +1901,7 @@ EngineControl::start_latency_detection ()
 	ARDOUR::AudioEngine::instance()->set_latency_input_port (lm_input_channel_combo.get_active_text());
 	ARDOUR::AudioEngine::instance()->set_latency_output_port (lm_output_channel_combo.get_active_text());
 
-	if (ARDOUR::AudioEngine::instance()->start_latency_detection (_measure_midi) == 0) {
+	if (ARDOUR::AudioEngine::instance()->start_latency_detection (_measure_midi ? true : false) == 0) {
 		lm_results.set_markup (string_compose (results_markup, _("Detecting ...")));
 		if (_measure_midi) {
 			latency_timeout = Glib::signal_timeout().connect (mem_fun (*this, &EngineControl::check_midi_latency_measurement), 100);
@@ -1781,6 +1915,13 @@ EngineControl::start_latency_detection ()
 		lm_output_channel_combo.set_sensitive (false);
 		lm_running = true;
 	}
+
+	lm_back_button_signal.disconnect();
+	if (_measure_midi) {
+		lm_back_button_signal = lm_back_button.signal_clicked().connect (sigc::bind (sigc::mem_fun (notebook, &Gtk::Notebook::set_current_page), midi_tab));
+	} else {
+		lm_back_button_signal = lm_back_button.signal_clicked().connect (sigc::bind (sigc::mem_fun (notebook, &Gtk::Notebook::set_current_page), 0));
+	}
 }
 
 void
@@ -1813,16 +1954,16 @@ void
 EngineControl::use_latency_button_clicked ()
 {
 	if (_measure_midi) {
-#if 0 // TODO
 		ARDOUR::MIDIDM* mididm = ARDOUR::AudioEngine::instance()->mididm ();
 		if (!mididm) {
 			return;
 		}
 		ARDOUR::framecnt_t frames_total = mididm->latency();
 		ARDOUR::framecnt_t extra = frames_total - ARDOUR::AudioEngine::instance()->latency_signal_delay();
-		uint32_t one_way = extra / 2;
-		// TODO assign to all or one specific device
-#endif
+		uint32_t one_way = max ((ARDOUR::framecnt_t) 0, extra / 2);
+		_measure_midi->input_latency = one_way;
+		_measure_midi->output_latency = one_way;
+		notebook.set_current_page (midi_tab);
 	} else {
 		MTDM* mtdm = ARDOUR::AudioEngine::instance()->mtdm ();
 
@@ -1830,18 +1971,17 @@ EngineControl::use_latency_button_clicked ()
 			return;
 		}
 
-		uint32_t frames_total = mtdm->del();
-		uint32_t extra = frames_total - ARDOUR::AudioEngine::instance()->latency_signal_delay();
-		uint32_t one_way = extra/2;
+		double one_way = rint ((mtdm->del() - ARDOUR::AudioEngine::instance()->latency_signal_delay()) / 2.0);
+		one_way = std::max (0., one_way);
 
 		input_latency_adjustment.set_value (one_way);
 		output_latency_adjustment.set_value (one_way);
-	}
-
-	/* back to settings page */
 
-	notebook.set_current_page (0);
+		/* back to settings page */
+		notebook.set_current_page (0);
 }
+	}
+
 
 bool
 EngineControl::on_delete_event (GdkEventAny* ev)
@@ -1882,9 +2022,9 @@ EngineControl::engine_stopped ()
 	sample_rate_combo.set_sensitive (true);
 	buffer_size_combo.set_sensitive (true);
 }
-	
+
 void
-EngineControl::connect_disconnect_click() 
+EngineControl::connect_disconnect_click()
 {
 	if (ARDOUR::AudioEngine::instance()->running()) {
 		ARDOUR_UI::instance()->disconnect_from_engine ();
@@ -1896,14 +2036,19 @@ EngineControl::connect_disconnect_click()
 void
 EngineControl::calibrate_audio_latency ()
 {
-	_measure_midi = false;
+	_measure_midi.reset();
 	notebook.set_current_page (latency_tab);
 }
 
 void
-EngineControl::calibrate_midi_latency ()
+EngineControl::calibrate_midi_latency (MidiDeviceSettings s)
 {
-	_measure_midi = true;
+	_measure_midi = s;
 	notebook.set_current_page (latency_tab);
 }
 
+void
+EngineControl::configure_midi_devices ()
+{
+	notebook.set_current_page (midi_tab);
+}
diff --git a/gtk2_ardour/engine_dialog.h b/gtk2_ardour/engine_dialog.h
index bb077d0705..d5eee0dd2e 100644
--- a/gtk2_ardour/engine_dialog.h
+++ b/gtk2_ardour/engine_dialog.h
@@ -79,6 +79,7 @@ class EngineControl : public ArdourDialog, public PBD::ScopedConnectionList {
 
     Gtk::Label      have_control_text;
     Gtk::Button     control_app_button;
+    ArdourButton    midi_devices_button;
 
     Gtk::Button     connect_disconnect_button;
 
@@ -91,7 +92,6 @@ class EngineControl : public ArdourDialog, public PBD::ScopedConnectionList {
     Gtk::Button       lm_use_button;
     Gtk::Button       lm_back_button;
     ArdourButton      lm_button_audio;
-    ArdourButton      lm_button_midi;
     Gtk::Label        lm_title;
     Gtk::Label        lm_results;
     Gtk::Table        lm_table;
@@ -106,7 +106,7 @@ class EngineControl : public ArdourDialog, public PBD::ScopedConnectionList {
     /* MIDI Tab */
 
     Gtk::VBox midi_vbox;
-    Gtk::Button midi_refresh_button;
+    Gtk::Button midi_back_button;
     Gtk::Table midi_device_table;
 
     /* MIDI ... JACK */
@@ -145,6 +145,35 @@ class EngineControl : public ArdourDialog, public PBD::ScopedConnectionList {
     void list_devices ();
     void show_buffer_duration ();
 
+    void configure_midi_devices ();
+
+    struct MidiDeviceSetting {
+	std::string name;
+	bool enabled;
+	uint32_t input_latency;
+	uint32_t output_latency;
+
+	MidiDeviceSetting (std::string n, bool en = true, uint32_t inl = 0, uint32_t oul = 0)
+	    : name (n)
+	    , enabled (en)
+	    , input_latency (inl)
+	    , output_latency (oul)
+	{}
+    };
+
+    typedef boost::shared_ptr<MidiDeviceSetting> MidiDeviceSettings;
+    bool _can_set_midi_latencies;
+    std::vector<MidiDeviceSettings> _midi_devices;
+
+    MidiDeviceSettings find_midi_device(std::string devicename) const {
+	for (std::vector<MidiDeviceSettings>::const_iterator p = _midi_devices.begin(); p != _midi_devices.end(); ++p) {
+	    if ((*p)->name == devicename) {
+		return *p;
+	    }
+	}
+	return MidiDeviceSettings();
+    }
+
     struct State {
 	std::string backend;
 	std::string driver;
@@ -157,6 +186,7 @@ class EngineControl : public ArdourDialog, public PBD::ScopedConnectionList {
 	uint32_t output_channels;
 	bool active;
 	std::string midi_option;
+	std::vector<MidiDeviceSettings> midi_devices;
 
 	State() 
 		: input_latency (0)
@@ -215,8 +245,12 @@ class EngineControl : public ArdourDialog, public PBD::ScopedConnectionList {
 
     void connect_disconnect_click ();
     void calibrate_audio_latency ();
-    void calibrate_midi_latency ();
-    bool _measure_midi;
+    void calibrate_midi_latency (MidiDeviceSettings);
+
+    MidiDeviceSettings _measure_midi;
+    void midi_latency_adjustment_changed(Gtk::Adjustment *, MidiDeviceSettings, bool);
+    bool midi_device_enabled_toggled(GdkEventButton* ev, ArdourButton *, MidiDeviceSettings);
+    sigc::connection lm_back_button_signal;
 };
 
 #endif /* __gtk2_ardour_engine_dialog_h__ */