+ uint32_t rgba () const { return _rgba; }
+
+ /** set route-group color and notify UI about change */
+ void set_rgba (uint32_t);
+
+ /* directly set color only, used to convert old 5.x gui-object-state
+ * to libardour color */
+ void migrate_rgba (uint32_t color) { _rgba = color; }
+
+private: