If I have Chobby on my first screen and then start a game, I cannot put Chobby on my second screen even though it is in windowed mode, which seems to do not apply while playing. If I put Chobby on my second screen first and then start a game, ZK appears on my first screen as it should, but only in a part of the screen with the resolution of my second screen, which is weird, and destroys my GUI panel positions.
Well, for now, I'm going to play on the first screen only. I talked with @_Shaman about how GUI panel position and size changes could be improved for resolution changes.
[Spoiler]Edit: Here's a screenshot made when Chobby was opened on the first screen (on the left in the picture) and a game started, which is then on the second screen on the right with the first screen's resolution. The blue rectangle on the left is the complete second screen. The small black ractangle at the bottom left hand side actually doesn't exist. I's only there, because both screens have a different resolution. The blue rectanges on the right are the rest of the first screen that isn't used by the game. My task bar would be visible at the bottom of the right screen. I have cut it off for privacy reasons. I used GUI tweak mode to show how my panel positions were changed.