- cairo_move_to (cr, width * 0.3, height);
- cairo_line_to (cr, width * 0.3, height * 0.5);
- cairo_line_to (cr, width * 0.7, height * 0.5);
- cairo_line_to (cr, width * 0.7, height);
- cairo_move_to (cr, width * 0.5, height * 0.5);
- cairo_line_to (cr, width * 0.5, 0);
+ const float si_l = rint(width * 0.3) + .5;
+ const float si_c = rint(width * 0.5) + .5;
+ const float si_r = rint(width * 0.7) + .5;
+ const float si_m = rint(height * 0.5) + .5;
+
+ cairo_move_to (cr, si_l, height);
+ cairo_line_to (cr, si_l, si_m);
+ cairo_line_to (cr, si_r, si_m);
+ cairo_line_to (cr, si_r, height);
+
+ cairo_set_line_cap (cr, CAIRO_LINE_CAP_BUTT);
+ cairo_move_to (cr, si_c, si_m);
+ cairo_line_to (cr, si_c, 0);