Summary: "Fullscreen Mode"
You can set this option to window instead if you want to use
the fake fullscreen support (a borderless window the size of the current
display will be created instead of switching to real fullscreen).
Value: fullscreen ("Fullscreen") - Classic fullscreen mode (SDL_FULLSCREEN)
Value: desktop ("Fullscreen Desktop") - New fullscreen mode (SDL_FULLSCREEN_DESKTOP)
Value: window ("Fullscreen Window") - Frameless window with same size as desktop