[cairo] Rectange got clipped off

[ken carlino]

Hi,

I use the following code to draw Rectange in cairo

  cairo_rectangle(cr, x, y , w, h);
  cairo_set_source_rgb(cr, 1.0, 0.0, 0.0);
  cairo_stroke(cr);

But for some reason, if I draw (0, 0, 10, 20) when the surface is 100X 100.
The top/left lines of the rectangle are 'thinner' than the
bottom/right lines of the rectangle.

Is there a reason for that? and what is the default pixel width of each stroke?

Thank you.