Some GtkAboutDialog doc additions

gtk/gtkaboutdialog.c

@@ -91,6 +91,10 @@
  *                        "title" _("About ExampleCode"),
  *                        NULL);
  * </programlisting></informalexample>
+ *
+ * It is also possible to show a #GtkAboutDialog like any other #GtkDialog,
+ * e.g. using gtk_dialog_run(). In this case, you might need to know that
+ * the 'Close' button returns the #GTK_RESPONSE_CANCEL response id.
  */
 
 static GdkColor default_link_color = { 0, 0, 0, 0xeeee };