cause windowed mode is much better! you can switch to chats/firefox in 0,1 sec and back... fullwindow need 10 years to get back in the game... and with windowed you also can use skype and other progs as overlay
the most abuse windowed mode for overlay hacks and the most hacks only work in windowed mode so i think he want to use a hack
what kind of anticheat ? which server
darkguard > kill it @task
fairfight 2 > change the settings @.ini
other > idk