push group to paint ontop of a s

	cairo_push_group (cr);
		cairo_set_source_surface (cr,
			object->surface_buffer->surface,
			0.0f, 0.0f);
		cairo_paint (cr);
		cairo_set_source_rgba (cr, 0.0, 0.0, 0.0, 1.0);
		cairo_set_operator (cr, CAIRO_OPERATOR_ATOP);
		cairo_paint (cr);
	cairo_pop_group_to_source (cr);
	cairo_paint (cr);