An inactive player is showing up as logging into my game. Does this mean they are actually logging in and taking a look around the game, or can a ‘login’ be generated if they hit the ‘-’ sign to hide my game on their sticky list, or by some other means?

If I'm inactive and I show up in someone's game it's because I clicked the wrong game.

In reply to icosahedron152 (msg # 1):

It means that they are clicking on your game and at least looking at the main part of it.

Mobile can sometimes cause a false-alarm, if they've got a browser that auto-refreshes when they open it. The player might have a tab they haven't looked at in a month, but it keeps "logging them in".

Hmm, so the answer is ‘inconclusive’. There is no way to tell whether the person is there, but not communicating, whether they've momentarily 'dialled a wrong number', or whether some system link is ghosting. :(

Not the answer I was hoping for, but thanks for your responses, folks. :)

Yeah... unfortunately the server can't read minds, so it can't tell the difference between a deliberate log-in, an accidental click on the wrong link, or a device automatically reopening the last page it was on when it is turned on again.

The only thing you can be sure of is that at least one page in your game was open.

Thanks Ron.
Well, I'll try offering the hand of friendship to the ghostly presence again. If there's nobody there, there's nobody to see me talking to myself, right? :)

Personally, I tend to RMail after a while -  and if there is no response to that (in a couple of weeks)  assume they have left, drop the player from the game and start recruiting for a new players.

Update.
I tried talking again, and I’ve got my friend back. :) She’d been lurking, but hadn’t summoned up the necessary to reply to me. I’m not sure whether I persuaded her to converse by means of my winning personality, or whether she’s been here and John B’s advice had a salutary effect. We haven’t chatted in that much depth yet. The important thing is that we’re talking again, and that feels good. Thanks again, guys. :)