Usually when you run a game for the first time, or a game updates, it opens in fullscreen before it starts asking for internet access. Since I use the Interactive filter mode for the firewall, this gets quite annoying if "Enable Gamer mode when running applications in full-screen mode automatically" is enabled. The prompt just doesn't show up, and I have to quit the game and start over.
Right now we just have the option to "Disable Gamer mode automatically after X minutes", but as the title says I'd like to have an option to "Enable Gamer mode automatically after X minutes" too. So if I set that to 1 minute, Gamer mode would be automatically enabled 1 minute after I go into full-screen.