In a -gtk or -xlib environment, if I call cairo_get_target() and then use that surface to call
get_image_surface_width/height(), I get silly numbers. Is this the correct way to determine
the screen drawing size?

I have sample code to demo this, along the lines of:



  // find out our surface size
  cairo_surface_t *cs = cairo_get_target(cr);
  int width = cairo_image_surface_get_width(cs);
  int height = cairo_image_surface_get_height(cs);
#if DEBUG
  printf("surface area w: %d, h:%d\n",width,height);
#endif