[cairo] Does cairo always generate trapezoids where point.y lie on top/bottom?

[Clemens Eisserer]

Hi,

Does cairo's tesselator always generate trapezoids where the y-value
of the points specifying the edges lie on top/bottom?

I did some experiments, which suggest this is the case.
If so, why does cairo_traps still save the y values?

Thanks, Clemens