thanks for the reply. But after reading some documentations I think the problem we are facing is different from the one we initially thought.
Basically, after a number of minutes, which is different from both SESSION_TIMEOUT and HTTP DURATIONS, we get an exception showing a popup with "ADF_FACES-60097: null window id".
Unfortunately I cannot get the full stack trace at the moment, since for now I only got the screenshot from the guy who is testing the app, but I'll search for it if that looks something obscure.
Yes, we also thought about the AM timeout. But the default is 600 seconds. We get the popup with the excpetion after 4-5 minutes, which does not correspond to any of the three timeout we have set (session, am idle time, http request). There must be something else we did not take into consideration which is relate to this time interval.