time stamps

it'd be neat if time stamps (in messaging) were adaptable. we have the option to set the date/time of every message sent but the time stamps either show up every 3/5 messages or don't show up. it'd be nice if we were able to set it so that every time the time/date was changed from the previous (ex 19:45-19:49), the time stamp would show. or perhaps the option to decide whether there be a time stamp or not for that message. maybe i've missed this feature and if so i apologise, but yeah!