GDK/Cairo question

[Fabian Greffrath <fabian greffrath com>]

Dear GTK+-gurus,

I am currently in the process of teaching myself a bit of GDK/Cairo by 
porting a small application from using Pixmaps and Bitmaps to Cairo. 
Please find a short sample source attached below.

The source compiles fine and the application runs, but instead of 
displaying the PNG file, it only shows a black square with no apparent 
content.

Please help me, what am I missing or doing wrong?

Best regards,
Fabian

--

/*
gcc -o cairo_test cairo_test.c `pkg-config gdk-3.0 --cflags` 
`pkg-config gdk-3.0 --libs`
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

#include <gdk/gdk.h>

int main(int argc, char **argv)
{
  GdkEvent *event;
  GdkWindow *win;
  GdkWindowAttr attr;

  if (!gdk_init_check(&argc, &argv))
  {
    fprintf(stderr, "GDK init failed!\n");
    exit(-1);
  }

  cairo_surface_t *cs = cairo_image_surface_create_from_png
  ("/usr/share/empathy/icons/hicolor/48x48/apps/im-ekiga.png");
  /* just an example, use whatever PNG you want */

  attr.width = cairo_image_surface_get_width(cs);
  attr.height = cairo_image_surface_get_height(cs);
  attr.title = "cairo test";
  attr.event_mask = GDK_BUTTON_PRESS_MASK;
  attr.wclass = GDK_INPUT_OUTPUT;
  attr.window_type = GDK_WINDOW_TOPLEVEL;

  win = gdk_window_new(NULL, &attr, GDK_WA_TITLE);

  if (!win)
  {
    fprintf(stderr, "Cannot make toplevel window!\n");
    exit (-1);
  }

  cairo_t *gc = gdk_cairo_create(win);
  cairo_set_source_surface(gc, cs, 0, 0);
  cairo_paint(gc);
  cairo_destroy(gc);
  gdk_window_show(win);

  while (1)
  {
    event = gdk_event_get();
    if (event)
    {
      switch (event->type)
      {
        case GDK_DESTROY:
          exit(0);
          break;
        case GDK_BUTTON_PRESS:
          exit(0);
          break;
        default:
          break;
      }
    }
    usleep(100);
  }
  return 0;
}