I've got some problems using the Postscript backend of cairo. 
I guess it's a bug but it could just as well be my limited understanding
of cairo ...

So here's the problem:

The following code snippet should produce a line from the lower left corner
to the upper right corner of the picture:
------------------------------------------------------
  cairo_surface_t *surface=cairo_ps_surface_create("test.ps",200,200);
  cairo_t *cr=cairo_create(surface);

  cairo_matrix_t matrix;

  matrix.xx=1.0;
  matrix.xy=0.0;
  matrix.yx=0.0;
  matrix.yy=-1.0;
  
  matrix.x0=0.0;
  matrix.y0=200;

  cairo_set_matrix(cr,&matrix);

  cairo_move_to(cr,0,0);
  cairo_line_to(cr,200,200);
  cairo_stroke(cr);

  cairo_show_page(cr);
  cairo_destroy(cr);
  cairo_surface_destroy(surface);
----------------------------------------------------
it should actually be equivalent to
---------------------------------------------------
  cairo_move_to(cr,0,200);
  cairo_line_to(cr,200,0);
  cairo_stroke(cr);
----------------------------------------------------

These code snippets do produce the same result for the Xlib
and pdf backends, for the ps backend, the first snippet creates
a diagonal line that is shifted to the left, out of the bounding box,
so that it's only visible in the upper left corner. The second snippet 
gives the correct result. 
This was tested using the latest cairo version from cvs today (11/17/05)
which is 1.1.1, I think.

Kind regards,

Mike Wimmer