+\subsection{RTTI}
+
+wxWindows does not use run-time type information since wxWindows provides
+its own run-time type information system, implemented using macros.
+
+\subsection{Type of NULL}
+
+Some compilers (e.g. the native IRIX cc) define NULL to be 0L so that
+no conversion to pointers is allowed. Because of that, all these
+occurences of NULL in the GTK port use an explicit conversion such
+as
+
+{\small
+\begin{verbatim}
+ wxWindow *my_window = (wxWindow*) NULL;
+\end{verbatim}
+}
+
+It is recommended to adhere to this in all code using wxWindows as
+this make the code (a bit) more portable.
+