there are two of them. The PAGE\_CHANGING event is sent before the current
page is changed. It allows to the program to examine the current page (which
can be retrieved with
-\helpref{GetOldSelection()}wxnotebookeventgetoldselection}) and to veto the page
+\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.
event, otherwise PAGE\_CHANGED is probably enough. In any case, it is probably
unnecessary to process both events at once.
+{\bf NB:} under Windows, GetSelection() will return the same value as
+GetOldSelection() when called from PAGE\_CHANGING handler and not the page
+which is going to be selected if the handler doesn't call Veto().
+
\wxheading{Derived from}
\helpref{wxNotifyEvent}{wxnotifyevent}\\