Inactivity warning: "Are you still there?"

An inactivity reminder pop-up would be very helpful before auto-logging out users. Managers have complained about reaching the end of a probation logbook entry, only to be logged out suddenly and lose all their information.

A pop-up box asking the user if they're still there, with 'yes' and 'no' options, would be great. Selecting 'yes' could reset the timer.