fill style
cairo_set_line_width (cr, 6);

cairo_rectangle (cr, 12, 12, 232, 70);
cairo_new_sub_path (cr); cairo_arc (cr, 64, 64, 40, 0, 2*M_PI);
cairo_new_sub_path (cr); cairo_arc_negative (cr, 192, 64, 40, 0, -2*M_PI);

cairo_set_fill_rule (cr, CAIRO_FILL_RULE_EVEN_ODD);
cairo_set_source_rgb (cr, 0, 0.7, 0); cairo_fill_preserve (cr);
cairo_set_source_rgb (cr, 0, 0, 0); cairo_stroke (cr);

cairo_translate (cr, 0, 128);
cairo_rectangle (cr, 12, 12, 232, 70);
cairo_new_sub_path (cr); cairo_arc (cr, 64, 64, 40, 0, 2*M_PI);
cairo_new_sub_path (cr); cairo_arc_negative (cr, 192, 64, 40, 0, -2*M_PI);

cairo_set_fill_rule (cr, CAIRO_FILL_RULE_WINDING);
cairo_set_source_rgb (cr, 0, 0, 0.9); cairo_fill_preserve (cr);
cairo_set_source_rgb (cr, 0, 0, 0); cairo_stroke (cr);