title: How do I make the gtk code work?
body: <pre><code>vbox = gtk_vbox_new(FALSE, 0);
  gtk_container_add(GTK_CONTAINER(window), vbox);
  ...
  frame = gtk_fixed_new();
  gtk_container_add(GTK_CONTAINER(window), frame);
  ...
  </code></pre>
  
  <p>The above code will generate the warning below:</p>
  
  <blockquote>
    <p>Gtk-WARNING **: Attempting to add a
    widget with type GtkFixed to a
    GtkWindow, but as a GtkBin subclass a
    GtkWindow can only contain one widget
    at a time; it already contains a
    widget of type GtkVBox</p>
  </blockquote>
  
  <p>Which results in <code>frame</code> is not shown in the window.</p>
  
  <p>How can I make both <code>vbox</code> and <code>frame</code> show?</p>