This has been an issue forever and i'm amazed we don't have a resolution for it yet.
It seems some work was done on it in PUC - now you'll get a session timed out message. But that is no use if you;re accessing a report or a CDE dashboard directly.
Here's one of the (many) jiras:
So, any ideas on a resolution?
I'm pretty sure this must just be a config issue, i guess no one has looked into it deeply yet?