+Returns the currently selected page, or $-1$ if none was selected.
+
+{\bf NB:} under Windows, GetSelection() will return the same value as\rtfsp
+\helpref{GetOldSelection()}{wxnotebookeventgetoldselection} when called from
+{\tt EVT\_NOTEBOOK\_PAGE\_CHANGING} handler and not the page which is going to
+be selected. Also note that the values of selection and old selection returned
+for an event generated in response to a call to
+\helpref{wxNotebook::SetSelection}{wxnotebooksetselection} shouldn't be trusted
+as they are currently inconsistent under different platforms (but in this case
+you presumably don't need them anyhow as you already have the corresponding
+information).
+