+This class represents the events generated by a notebook control: currently,
+there are two of them. The PAGE\_CHANGING event is sent before the current
+page is changed. It allows the program to examine the current page (which
+can be retrieved with
+\helpref{GetOldSelection()}{wxnotebookeventgetoldselection}) and to veto the page
+change by calling \helpref{Veto()}{wxnotifyeventveto} if, for example, the
+current values in the controls of the old page are invalid.
+
+The second event - PAGE\_CHANGED - is sent after the page has been changed and
+the program cannot veto it any more, it just informs it about the page change.
+
+To summarize, if the program is interested in validating the page values
+before allowing the user to change it, it should process the PAGE\_CHANGING
+event, otherwise PAGE\_CHANGED is probably enough. In any case, it is probably
+unnecessary to process both events at once.