add signal for Plugin Status Changes (Hidden/Favorite)

libs/ardour/ardour/plugin_manager.h

@@ -78,6 +78,8 @@ class LIBARDOUR_API PluginManager : public boost::noncopyable {
 
 	/** plugins were added to or removed from one of the PluginInfoLists */
 	PBD::Signal0<void> PluginListChanged;
+	/** Plugin Hidden/Favorite status changed */
+	PBD::Signal0<void> PluginStatusesChanged;
 
   private:
 	struct PluginStatus {

libs/ardour/plugin_manager.cc

@@ -1123,6 +1123,7 @@ PluginManager::save_statuses ()
 		ofs << endl;
 	}
 	g_file_set_contents (path.c_str(), ofs.str().c_str(), -1, NULL);
+	PluginStatusesChanged (); /* EMIT SIGNAL */
 }
 
 void