if (_meter) {
_meter->ConfigurationChanged.connect (_configuration_connection, parent_invalidator, boost::bind (&LevelMeterBase::configuration_changed, this, _1, _2), gui_context());
if (_meter) {
_meter->ConfigurationChanged.connect (_configuration_connection, parent_invalidator, boost::bind (&LevelMeterBase::configuration_changed, this, _1, _2), gui_context());