- paint_surface (cr, priv->origin_surface, 0, - (height * progress), 0, page_area);
- paint_surface (cr, priv->dest_surface, 0, height * (1 - progress), 0, page_area);
+ paint_surface (cr, priv->origin_surface, 0, - (height * progress), 1., page_area);
+ paint_surface (cr, priv->dest_surface, 0, height * (1 - progress), 1., page_area);