Add padding to class structs

gtk/gtkeventbox.h

@@ -55,6 +55,12 @@ struct _GtkEventBox
 struct _GtkEventBoxClass
 {
   GtkBinClass parent_class;
+
+  /* Padding for future expansion */
+  void (*_gtk_reserved1) (void);
+  void (*_gtk_reserved2) (void);
+  void (*_gtk_reserved3) (void);
+  void (*_gtk_reserved4) (void);
 };
 
 GType	   gtk_event_box_get_type           (void) G_GNUC_CONST;