Asks to place a window in the fullscreen state. Note that operating system or the user can force the position of the window.
Demande de placer une fenêtre en plein écran.
_window_ : ObjGtk : any window already created.
_value_ : I : to place the window _window_ in thefullscreen state,_value_ must be at 1. To unset it, _value_ must be at 0.
Return : ObjGtk : the same window or nil if error.