sky330,
The B777 has such a system. I'm not sure of it's operating parameters, but if, after a certain time, there has been no pilot input to anything, the Master Caution with it's raucous aural alert sounds.
On a long, steady as she goes, route sector, it pays to twiddle the Heading knob or something, to prevent it's going off.
Regards,
Old Smokey