diff --git a/gtk2_ardour/editor.cc b/gtk2_ardour/editor.cc
index a2fc9bc712..25ca1c9302 100644
--- a/gtk2_ardour/editor.cc
+++ b/gtk2_ardour/editor.cc
@@ -313,6 +313,7 @@ Editor::Editor ()
 	last_update_frame = 0;
         pre_press_cursor = 0;
 	_drags = new DragManager (this);
+        lock_dialog = 0;
 	current_mixer_strip = 0;
 	tempo_lines = 0;
 
diff --git a/gtk2_ardour/editor.h b/gtk2_ardour/editor.h
index 6539ea0b26..2de680ae40 100644
--- a/gtk2_ardour/editor.h
+++ b/gtk2_ardour/editor.h
@@ -1359,6 +1359,9 @@ class Editor : public PublicEditor, public PBD::ScopedConnectionList, public ARD
 	DragManager* _drags;
 
 	void escape ();
+        void lock ();
+        void unlock ();
+        ArdourDialog *lock_dialog;
 
 	Gtk::Menu fade_context_menu;
 	void popup_fade_context_menu (int, int, ArdourCanvas::Item*, ItemType);
diff --git a/gtk2_ardour/editor_ops.cc b/gtk2_ardour/editor_ops.cc
index c4b5309333..c8d08722f6 100644
--- a/gtk2_ardour/editor_ops.cc
+++ b/gtk2_ardour/editor_ops.cc
@@ -7060,3 +7060,44 @@ Editor::toggle_midi_input_active (bool flip_others)
 	
 	_session->set_exclusive_input_active (rl, onoff, flip_others);
 }
+
+
+void
+Editor::lock ()
+{
+	if (!lock_dialog) {
+		lock_dialog = new ArdourDialog (string_compose (_("%1: Locked"), PROGRAM_NAME), true);
+
+		Gtk::Image* padlock = manage (new Gtk::Image (::get_icon ("padlock_closed")));
+		lock_dialog->get_vbox()->pack_start (*padlock);
+
+		ArdourButton* b = manage (new ArdourButton);
+		b->set_name ("lock button");
+		b->set_markup (string_compose ("<span size=\"large\" weight=\"bold\">%1</span>", _("Click to unlock")));
+		b->signal_clicked.connect (sigc::mem_fun (*this, &Editor::unlock));
+		lock_dialog->get_vbox()->pack_start (*b);
+		
+		lock_dialog->get_vbox()->show_all ();
+		lock_dialog->set_size_request (200, 200);
+	}
+	
+#ifdef __APPLE__
+	/* The global menu bar continues to be accessible to applications
+	   with modal dialogs, which means that we need to desensitize
+	   all items in the menu bar. Since those items are really just
+	   proxies for actions, that means disabling all actions.
+	*/
+	ActionManager::disable_all_actions ();
+#endif
+	lock_dialog->present ();
+}
+
+void
+Editor::unlock ()
+{
+	lock_dialog->hide ();
+
+#ifdef __APPLE__
+	ActionManager::pop_action_state ();
+#endif	
+}