+ _curve->set_fill_mode (ArdourCanvas::FramedCurve::Inside);
+ _curve->set_points_per_segment (3);
+
+ points = new ArdourCanvas::Points ();
+ points->push_back (ArdourCanvas::Duple (0.0, 0.0));
+ points->push_back (ArdourCanvas::Duple (1.0, 0.0));
+ points->push_back (ArdourCanvas::Duple (1.0, curve_height));
+ points->push_back (ArdourCanvas::Duple (0.0, curve_height));
+