I don't know about you, but every time I press the red "Revenge" button I get a message saying the user is online or has a shield. This feature is pretty useless as is. If I wanted revenge on a specific person, I would have to keep checking all day long.
My proposal to fix is this... When a user exits the game, don't let them be attacked right away. For the first 60 mins (more or less), they can only be revenge attacked and not attacked by a random person searching. After 60 mins, anyone can attack the base. This would make it a lot easier to use revenge attacks, and lets face it, the time it takes to log off and get attacked by somebody is ridiculous anyway. I switch apps to my email sometimes to read a short message, and I'm attacked within a 2 mins. At least with this proposal I would have 60 mins where I am much less likely to get attacked, since they can only be revenges. So this kinda fixes 2 annoying things at the same time.