If that's the case, then why am I able to do something like the following:
I join a channel (let's call it #timbuktu)
Upon joining I see that Fred, George, and Mary are in the nicklist
Fred & George greet me, and I respond, also saying Hi to Mary
Mary doesn't respond, so I wait for 5 minutes then issue //echo -a $nick(#timbuktu,Mary).idle
This returns a value of 16000
That's an idle time of 16,000 seconds (4 hrs 26 mins 40 secs)
mIRC has to be getting that information from somewhere, and it can't be based on the time since I joined, since it's only been a little over 5 minutes since I joined, and yet Mary's idle time in the channel is returning nearly 4 1/2 hours.