Hides the main window of the terminal and sets the visible
        flag to False.

def hide(self):
        """Hides the main window of the terminal and sets the visible
        flag to False.
        """
        if not HidePrevention(self.window).may_hide():
            return
        self.hidden = True
        self.get_widget('window-root').unstick()
        self.window.hide()