Attack champion only toggle?

Hi everyone, i had an idea while playing a game and i'd liked to have opinion for it. I know there's already a key you press to attack only champion, but why not add one wich lock this mode. It means you could press the key instead of holding it and you'll attack only champ. Press again to desactivate, pretty much like the camera lock. I'd personally like to have this option and i dont know if other player would too? Please share some thought. (^.^)