position_control->Changed.connect (connections, invalidator(*this), boost::bind (&MonoPanner::value_change, this), gui_context());
ColorsChanged.connect (sigc::mem_fun (*this, &MonoPanner::color_handler));
position_control->Changed.connect (connections, invalidator(*this), boost::bind (&MonoPanner::value_change, this), gui_context());
ColorsChanged.connect (sigc::mem_fun (*this, &MonoPanner::color_handler));