fullscreen_toggle_app_kivy.py

class FullscreenToggleApp(App):
    fullscreen = BooleanProperty(False)
    maximized = BooleanProperty(False)
    last_size = ListProperty([0, 0])
    last_pos = ListProperty([0, 0])
    _window_update_lock = False

    def build(self):
        self.root_widget = RootWidget(self)
        if platform in ('linux', 'win'):
            Clock.schedule_interval(self._update_window_pos, 0.2)
            self.root_widget.bind(size=self._update_window_size)
        return self.root_widget

    def _update_window_size(self, _, value):
        if not self._window_update_lock:
            self.last_size = value

    def _update_window_pos(self, *args):
        if not self._window_update_lock:
            self.last_pos = [Window.left, Window.top]
  
    def set_window_pos(self, x, y):
            Window.left = x
            Window.top = y
            Window.show()
            Window.restore()

      def set_window_size(self, size):
          Window.size = size
          Window.hide()

      def toggle_fullscreen(self, *args):
          if self.fullscreen:
              Window.fullscreen = False
              self.fullscreen = False
              new_pos = (self.last_pos)
              new_size = (self.last_size)
              Clock.schedule_once(
                  lambda dt: self.set_window_pos(*new_pos), 0.2)
              Clock.schedule_once(
                  lambda dt: self.set_window_size(new_size), 0)
              self._window_update_lock = False
          else:
              self._window_update_lock = True
              Window.maximize()
              Clock.schedule_once(
                  lambda dt: setattr(Window, 'fullscreen', True), 0.2)
              self.fullscreen = True
              
          lock_keyboard_input_somehow_temporarily()