Define SimpleMessageBoxException

src/AudacityException.cpp

@@ -50,6 +50,21 @@ MessageBoxException::~MessageBoxException()
       wxAtomicDec( sOutstandingMessages );
 }
 
+SimpleMessageBoxException::~SimpleMessageBoxException()
+{
+}
+
+wxString SimpleMessageBoxException::ErrorMessage() const
+{
+   return message;
+}
+
+std::unique_ptr< AudacityException > SimpleMessageBoxException::Move()
+{
+   return std::unique_ptr< AudacityException >
+   { safenew SimpleMessageBoxException{ std::move( *this ) } };
+}
+
 // This is meant to be invoked via wxEvtHandler::CallAfter
 void MessageBoxException::DelayedHandlerAction()
 {