title: How to make a GTK3+ window with a background image
body: <p>The Pixbuf method doesn't work anymore for GTK3+ because obsoleted/removed. I want to put a background image in the back of a GtkFixed, on the gdk part of the GtkWindow or a GtkBox. I believe I need Cairo graphics library to do this. </p>
  
  <p>Can a pleasant soul guide me in the right direction? </p>