When playing a game one may want to disable compositing to enhance the performance but also to avoid effects when moving the mouse to the edge of the screen. For example I have set a trigger for the desktop grid in the lower left corner. Right now it's hard to tell if the compositor is enabled or disabled if you use the hot keys (#416305). I test it by actually moving the mouse to the corner... It's way too cumbersome to always open the systemsettings and navigate to the setting's page. However, it were even better if the compositor becomes automatically disabled whenever a full screen game runs, so that the player does not need think about it. When changing the virtual desktop to one where no game is running, it may be enabled again automatically. Is this possible? Does it make sense to you? :)
KWin has no knowledge about whether the given window is a game or a terminal, etc. On the other hand, the game could set _KDE_NET_WM_BLOCK_COMPOSITING on its window to block compositing. You could also create a window rule for the game to block compositing.
Got it, thanks! I will look into it :)