// if the event object == this because the book control can have other
// subcontrols inside it (e.g. wxSpinButton in case of a notebook in wxUniv)
wxWindow *source = wxStaticCast(event.GetEventObject(), wxWindow);
// if the event object == this because the book control can have other
// subcontrols inside it (e.g. wxSpinButton in case of a notebook in wxUniv)
wxWindow *source = wxStaticCast(event.GetEventObject(), wxWindow);