<s:token> - should be able to detect back/forward?

Hi!

I have tried out shales in order to be able to prevent the user from pressing the back/forward buttons or
resubmitting. (Meaning: ignoring that request and either redirecting to an error page or at least
showing an error message.) 

It seems to me, though, that all it is able to do is detect resubmits (and afterwards it always shows the error
message, even if I 'normally' submit the form again).

Am I not setting it up correctly or is it supposed to work this way?

Thanks,
Agoston