This isn't as much a bug as it is annoying.
Whenever the XP Tracker AFK alert goes off, it takes focus off of the RS process and focuses the Alt1 process.
Is this supposed to happen? Somewhat annoying when typing, etc. in game.
I am aware of this, it also happens whenever a new overlay is created. Windows seems to insist on giving these windows focus even after telling it that they can't be focused.
Okay so update on this. I run 2 RuneScape clients (NXT) at the same time since I play on two accounts at once, and if I have my 2nd client focused while Alt1 is detecting my other client, it doesn't steal focus away from it. It only seems to steal away focus from the client Alt1 is linked to... I'm not sure what you make of this, but yeah, that's out there.