Even though I have the "Pause wallpaper changes while a fullscreen app is running", DisplayFusion changes wallpaper when the game LOTRO (Lord of the Rings Online) is fullscreen on one monitor. The game has a launcher app written in .NET that is not full screen and hangs around in the backround while the game is running, maybe that has to do with it.
The game is free to play and download so you could test it yourself.
I hate the lag when i'm stuck with 10 orcs around me (or is it my character..? I'm start to loosing it here..)