- Gtkmm2ext::rounded_rectangle (cr, 5, rint (.5 * (hh - w) - 1), h + 2, w + 2, 4);
+ Gtkmm2ext::rounded_rectangle (cr, 5, 5, w + 2, h + 2, 4);
+ cr->set_source_rgba (.1, .1, .1, 0.7);
+ cr->fill ();
+ cr->move_to (6, 6);
+ cr->set_source_rgba (.9, .9, .9, 1.0);
+ layout->show_in_cairo_context (cr);
+
+ // y-axis label
+ layout->set_text (_("Multiplicity"));
+ layout->get_pixel_size (w, h);
+ Gtkmm2ext::rounded_rectangle (cr, 5, hh - w - 3, h + 2, w + 2, 4);