diff --git a/gtk2_ardour/editor.cc b/gtk2_ardour/editor.cc
index 12782f33e6..25fdd1f7f4 100644
--- a/gtk2_ardour/editor.cc
+++ b/gtk2_ardour/editor.cc
@@ -2789,7 +2789,7 @@ Editor::setup_toolbar ()
 #ifdef GTKOSX
 	const guint32 FUDGE = 38; // Combo's are stupid - they steal space from the entry for the button
 #else
-	const guint32 FUDGE = 18; // Combo's are stupid - they steal space from the entry for the button
+	const guint32 FUDGE = 24; // Combo's are stupid - they steal space from the entry for the button
 #endif
 
 	/* Mode Buttons (tool selection) */
diff --git a/gtk2_ardour/editor_audio_import.cc b/gtk2_ardour/editor_audio_import.cc
index 2daec610bd..9bc4b7b3ba 100644
--- a/gtk2_ardour/editor_audio_import.cc
+++ b/gtk2_ardour/editor_audio_import.cc
@@ -864,7 +864,7 @@ Editor::finish_bringing_in_audio (boost::shared_ptr<AudioRegion> region, uint32_
 void *
 Editor::_import_thread (void *arg)
 {
-	PBD::ThreadCreated (pthread_self(), X_("Import"));
+	PBD::notify_gui_about_thread_creation (pthread_self(), X_("Import"));
 
 	Editor *ed = (Editor *) arg;
 	return ed->import_thread ();
diff --git a/gtk2_ardour/editor_ops.cc b/gtk2_ardour/editor_ops.cc
index b4cb4c688c..9c0c896b14 100644
--- a/gtk2_ardour/editor_ops.cc
+++ b/gtk2_ardour/editor_ops.cc
@@ -3554,7 +3554,7 @@ Editor::unfreeze_route ()
 void*
 Editor::_freeze_thread (void* arg)
 {
-	PBD::ThreadCreated (pthread_self(), X_("Freeze"));
+	PBD::notify_gui_about_thread_creation (pthread_self(), X_("Freeze"));
 	return static_cast<Editor*>(arg)->freeze_thread ();
 }
 
diff --git a/gtk2_ardour/editor_timefx.cc b/gtk2_ardour/editor_timefx.cc
index 8caa808979..c1e1403ca2 100644
--- a/gtk2_ardour/editor_timefx.cc
+++ b/gtk2_ardour/editor_timefx.cc
@@ -427,7 +427,7 @@ Editor::do_timefx (TimeFXDialog& dialog)
 void*
 Editor::timefx_thread (void *arg)
 {
-	PBD::ThreadCreated (pthread_self(), X_("TimeFX"));
+	PBD::notify_gui_about_thread_creation (pthread_self(), X_("TimeFX"));
 
 	TimeFXDialog* tsd = static_cast<TimeFXDialog*>(arg);
 
diff --git a/gtk2_ardour/export_region_dialog.cc b/gtk2_ardour/export_region_dialog.cc
index cb3804c11b..1241d2bf90 100644
--- a/gtk2_ardour/export_region_dialog.cc
+++ b/gtk2_ardour/export_region_dialog.cc
@@ -62,7 +62,7 @@ ExportRegionDialog::export_audio_data()
 void*
 ExportRegionDialog::_export_region_thread (void *arg)
 {
-	PBD::ThreadCreated (pthread_self(), X_("Export Region"));
+	PBD::notify_gui_about_thread_creation (pthread_self(), X_("Export Region"));
 
 	static_cast<ExportRegionDialog*>(arg)->export_region ();
 	return 0;
diff --git a/gtk2_ardour/sfdb_ui.cc b/gtk2_ardour/sfdb_ui.cc
index 8492ae1e05..e1481a19fc 100644
--- a/gtk2_ardour/sfdb_ui.cc
+++ b/gtk2_ardour/sfdb_ui.cc
@@ -714,7 +714,7 @@ SoundFileBrowser::found_search_clicked ()
 void*
 freesound_search_thread_entry (void* arg)
 {
-	PBD::ThreadCreated (pthread_self(), X_("Freesound Search"));
+	PBD::notify_gui_about_thread_creation (pthread_self(), X_("Freesound Search"));
 
 	static_cast<SoundFileBrowser*>(arg)->freesound_search_thread ();
 	
diff --git a/libs/ardour/analyser.cc b/libs/ardour/analyser.cc
index 2e14c74b86..28eeeb190c 100644
--- a/libs/ardour/analyser.cc
+++ b/libs/ardour/analyser.cc
@@ -75,7 +75,7 @@ Analyser::queue_source_for_analysis (boost::shared_ptr<Source> src, bool force)
 void
 Analyser::work ()
 {
-	PBD::ThreadCreated (pthread_self(), string ("analyser-") + to_string (pthread_self(), std::dec));
+	PBD::notify_gui_about_thread_creation (pthread_self(), string ("analyser-") + to_string (pthread_self(), std::dec));
 
 	while (true) {
 		analysis_queue_lock.lock ();
diff --git a/libs/ardour/audioengine.cc b/libs/ardour/audioengine.cc
index 8ea76f5844..787ed2346b 100644
--- a/libs/ardour/audioengine.cc
+++ b/libs/ardour/audioengine.cc
@@ -100,7 +100,7 @@ _thread_init_callback (void *arg)
 	   knows about it.
 	*/
 
-	PBD::ThreadCreatedWithRequestSize (pthread_self(), X_("Audioengine"), 4096);
+	PBD::notify_gui_about_thread_creation (pthread_self(), X_("Audioengine"), 4096);
 }
 
 int
diff --git a/libs/ardour/osc.cc b/libs/ardour/osc.cc
index 101e4cbd93..04090d35a1 100644
--- a/libs/ardour/osc.cc
+++ b/libs/ardour/osc.cc
@@ -302,7 +302,7 @@ OSC::get_unix_server_url()
 void *
 OSC::_osc_receiver(void * arg)
 {
-	PBD::ThreadCreated (pthread_self(), X_("OSC"));
+	PBD::notify_gui_about_thread_creation (pthread_self(), X_("OSC"));
 	static_cast<OSC*> (arg)->osc_receiver();
 	return 0;
 }
diff --git a/libs/ardour/session_butler.cc b/libs/ardour/session_butler.cc
index 92ebc50580..9d4ee5678b 100644
--- a/libs/ardour/session_butler.cc
+++ b/libs/ardour/session_butler.cc
@@ -155,7 +155,7 @@ Session::wait_till_butler_finished ()
 void *
 Session::_butler_thread_work (void* arg)
 {
-	PBD::ThreadCreated (pthread_self(), X_("Butler"));
+	PBD::notify_gui_about_thread_creation (pthread_self(), X_("Butler"));
 	return ((Session *) arg)->butler_thread_work ();
 	return 0;
 }
diff --git a/libs/ardour/session_midi.cc b/libs/ardour/session_midi.cc
index 2f090ec4eb..ffd30fb42c 100644
--- a/libs/ardour/session_midi.cc
+++ b/libs/ardour/session_midi.cc
@@ -1155,7 +1155,7 @@ Session::midi_thread_work ()
 	bool restart;
 	vector<MIDI::Port*> ports;
 
-	PBD::ThreadCreatedWithRequestSize (pthread_self(), X_("MIDI"), 2048);
+	PBD::notify_gui_about_thread_creation (pthread_self(), X_("MIDI"), 2048);
 
 	memset (&rtparam, 0, sizeof (rtparam));
 	rtparam.sched_priority = 9; /* XXX should be relative to audio (JACK) thread */
diff --git a/libs/ardour/source_factory.cc b/libs/ardour/source_factory.cc
index 7942bfa5e0..9064faa56d 100644
--- a/libs/ardour/source_factory.cc
+++ b/libs/ardour/source_factory.cc
@@ -54,7 +54,7 @@ std::list<boost::weak_ptr<AudioSource> > SourceFactory::files_with_peaks;
 static void 
 peak_thread_work ()
 {
-	PBD::ThreadCreated (pthread_self(), string ("peakbuilder-") + to_string (pthread_self(), std::dec));
+	PBD::notify_gui_about_thread_creation (pthread_self(), string ("peakbuilder-") + to_string (pthread_self(), std::dec));
 
 	while (true) {
 
diff --git a/libs/pbd/pbd/abstract_ui.cc b/libs/pbd/pbd/abstract_ui.cc
index 7b21390764..bc33fc9a39 100644
--- a/libs/pbd/pbd/abstract_ui.cc
+++ b/libs/pbd/pbd/abstract_ui.cc
@@ -17,7 +17,6 @@ AbstractUI<RequestObject>::AbstractUI (string name, bool with_signal_pipes)
 		throw failed_constructor();
 	}
 
-	PBD::ThreadCreated.connect (mem_fun (*this, &AbstractUI<RequestObject>::register_thread));
 	PBD::ThreadLeaving.connect (mem_fun (*this, &AbstractUI<RequestObject>::unregister_thread));
 	PBD::ThreadCreatedWithRequestSize.connect (mem_fun (*this, &AbstractUI<RequestObject>::register_thread_with_request_count));
 }
diff --git a/libs/pbd/pbd/pthread_utils.h b/libs/pbd/pbd/pthread_utils.h
index 157dab6c12..dd91e0a2b1 100644
--- a/libs/pbd/pbd/pthread_utils.h
+++ b/libs/pbd/pbd/pthread_utils.h
@@ -35,9 +35,11 @@ void pthread_exit_pbd (void* status);
 std::string pthread_name ();
 
 namespace PBD {
-  extern sigc::signal<void,pthread_t,std::string> ThreadCreated;
-  extern sigc::signal<void,pthread_t>             ThreadLeaving;
-  extern sigc::signal<void,pthread_t,std::string,uint32_t> ThreadCreatedWithRequestSize;
+	extern void notify_gui_about_thread_creation (pthread_t, std::string, int requests = 256);
+	extern void notify_gui_about_thread_exit (pthread_t);
+
+	extern sigc::signal<void,pthread_t>             ThreadLeaving;
+	extern sigc::signal<void,pthread_t,std::string,uint32_t> ThreadCreatedWithRequestSize;
 }
 
 #endif /* __pbd_pthread_utils__ */
diff --git a/libs/pbd/pthread_utils.cc b/libs/pbd/pthread_utils.cc
index 0c9d574e73..c63f988af3 100644
--- a/libs/pbd/pthread_utils.cc
+++ b/libs/pbd/pthread_utils.cc
@@ -30,15 +30,31 @@ using namespace std;
 typedef std::map<string,pthread_t> ThreadMap;
 static ThreadMap all_threads;
 static pthread_mutex_t thread_map_lock = PTHREAD_MUTEX_INITIALIZER;
+static pthread_mutex_t gui_notify_lock = PTHREAD_MUTEX_INITIALIZER;
 
 namespace PBD {
-   sigc::signal<void,pthread_t,std::string> ThreadCreated;
    sigc::signal<void,pthread_t>             ThreadLeaving;
    sigc::signal<void,pthread_t,std::string,uint32_t> ThreadCreatedWithRequestSize;
 }
 
 using namespace PBD;
 
+void
+PBD::notify_gui_about_thread_creation (pthread_t thread, std::string str, int request_count)
+{
+	pthread_mutex_lock (&gui_notify_lock);
+	ThreadCreatedWithRequestSize (thread, str, request_count);
+	pthread_mutex_unlock (&gui_notify_lock);
+}
+
+void
+PBD::notify_gui_about_thread_exit (pthread_t thread)
+{
+	pthread_mutex_lock (&gui_notify_lock);
+	ThreadLeaving (thread);
+	pthread_mutex_unlock (&gui_notify_lock);
+}
+
 int  
 pthread_create_and_store (string name, pthread_t  *thread, pthread_attr_t *attr, void * (*start_routine)(void *), void * arg)
 {
diff --git a/libs/surfaces/control_protocol/basic_ui.cc b/libs/surfaces/control_protocol/basic_ui.cc
index 7c032524f9..cda5497700 100644
--- a/libs/surfaces/control_protocol/basic_ui.cc
+++ b/libs/surfaces/control_protocol/basic_ui.cc
@@ -49,10 +49,9 @@ BasicUI::~BasicUI ()
 void
 BasicUI::register_thread (std::string name)
 {
-	PBD::ThreadCreated (pthread_self(), name);
+	PBD::notify_gui_about_thread_creation (pthread_self(), name);
 }
 
-
 void
 BasicUI::access_action ( std::string action_path ) 
 {
diff --git a/libs/surfaces/frontier/tranzport/tranzport_control_protocol.cc b/libs/surfaces/frontier/tranzport/tranzport_control_protocol.cc
index c874a05de5..5b413273ea 100644
--- a/libs/surfaces/frontier/tranzport/tranzport_control_protocol.cc
+++ b/libs/surfaces/frontier/tranzport/tranzport_control_protocol.cc
@@ -1029,7 +1029,7 @@ TranzportControlProtocol::monitor_work ()
 	uint8_t offline = 0;
 
 
-	PBD::ThreadCreated (pthread_self(), X_("Tranzport"));
+	PBD::notify_gui_about_thread_creation (pthread_self(), X_("Tranzport"));
 	pthread_setcancelstate (PTHREAD_CANCEL_ENABLE, 0);
 	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
 	next_track ();
diff --git a/libs/surfaces/mackie/mackie_control_protocol_poll.cc b/libs/surfaces/mackie/mackie_control_protocol_poll.cc
index b760b05aee..1b087222cd 100644
--- a/libs/surfaces/mackie/mackie_control_protocol_poll.cc
+++ b/libs/surfaces/mackie/mackie_control_protocol_poll.cc
@@ -41,8 +41,7 @@ bool MackieControlProtocol::probe()
 
 void * MackieControlProtocol::monitor_work()
 {
-	// What does ThreadCreatedWithRequestSize do?
-	PBD::ThreadCreated (pthread_self(), X_("Mackie"));
+	PBD::notify_gui_about_thread_creation (pthread_self(), X_("Mackie"));
 
 	pthread_setcancelstate (PTHREAD_CANCEL_ENABLE, 0);
 	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
diff --git a/libs/surfaces/tranzport/init.cc b/libs/surfaces/tranzport/init.cc
index 94f85bdc56..726cb60d49 100644
--- a/libs/surfaces/tranzport/init.cc
+++ b/libs/surfaces/tranzport/init.cc
@@ -173,7 +173,7 @@ TranzportControlProtocol::monitor_work ()
 	bool first_time = true;
 	uint8_t offline = 0;
 
-	PBD::ThreadCreated (pthread_self(), X_("Tranzport"));
+	PBD::notify_gui_about_thread_creation (pthread_self(), X_("Tranzport"));
 	pthread_setcancelstate (PTHREAD_CANCEL_ENABLE, 0);
 	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
 	rtpriority_set();