Sometimes when I attempt to attack an opponent, I get a message along the lines of "Can not attack, opponent is online". I've also of course observed that I never seem to get attacked while I am online. Is it possible to indefinitely "filibuster" attacks by remaining online?
One slight edit, that the games determination of "activity" seems to involve more than just scrolling around. When I just scroll around, I still seem to hit the activity timeout, but if I select building by clicking on them, the timeout is never triggered.