title: GtkButton just shows text but no image
body: <p>I have a GtkButton inside a GtkHButtonBox that doesn't show the image I'm adding to it. It just shows the text. Here's the code:</p>
  
  <pre><code>GtkImage *image = (GtkImage *) gtk_image_new_from_file("Gateway-LT21-netbook-2-540x359");
  GtkButton *button = (GtkButton *) gtk_button_new_with_label("test");
  gtk_button_set_image(button, (GtkWidget *) image);
  </code></pre>
  
  <p>Is there something I'm missing?</p>