Lond long ago a friend told me about this sim so I had a go playing the demo. ( Maybe 0.5U ? Don't remember clearly. At that time XRT is in demo. ) In that version when you alt + tab to another window the audio is still on, no matter it's full screen mode or windowed. But in today's LFS, when the game is in inactive state sound will be cut off. Can a "output audio when inactive" option be added to the program ? Would be useful if you watch a race and talk to someone via instant messaging at the same time.