I need to test this further, was hoping others could jump in and help me test this. As we know, the game auto-disconnects you after a very short time of inactivity. Which can be frustrating if you're in the middle of bounties etc and something comes up, taking you AFK for 15 min+.
I noticed through observation that if I press "O" and bring up my F/L, I can minimize my screen and come back to my game, no auto-disconnect occurring so long as my F/L is up.
I haven't been able to test it beyond 45 minutes, but will further test this later on. Would like some confirmation of this theory by way of others helping to test this placehold method.
I went AFK for about 2 hours and it did indeed drop me. However twice today (and several other times over recent days) I've managed to keep a game up for 30-45 minutes + by doing this, when it simply won't go more than approx 15 minutes without doing this.
So....there's a few possibilities going on here;
1) Leaving your F/L up does indeed extend the length of time you can AFK without D/C, limited to under an hour perhaps.
2) Something else is at play causing an exception and this is just a coincidental mistaken observation.
3) Perhaps certain activity with your F/L causes the game to think you're active when you're not. If this activity stops for too long, it then drops you.
4) I'm crazy and the voices in my head have fed me bad information, again.
As apinahirvi mentioned, there have been times where I was AFK for far longer and I kept my game, not taking note of anything in particular that I did to cause this.