ac = pannable->pan_azimuth_control;
_stereo_panner->StartPositionGesture.connect (sigc::bind (sigc::mem_fun (*this, &PannerUI::start_touch),
ac = pannable->pan_azimuth_control;
_stereo_panner->StartPositionGesture.connect (sigc::bind (sigc::mem_fun (*this, &PannerUI::start_touch),