_panner->StateChanged.connect (connections, invalidator (*this), boost::bind (&PannerUI::update_pan_state, this), gui_context());
/* new panner object, force complete reset of panner GUI
_panner->StateChanged.connect (connections, invalidator (*this), boost::bind (&PannerUI::update_pan_state, this), gui_context());
/* new panner object, force complete reset of panner GUI