Asks to unmaximize window. Note that you shouldn’t assume the window is definitely unmaximized afterward, because other entities (e.g. the user or [window manager][gtk-X11-arch]) could maximize it again, and not all window managers honor requests to unmaximize. But normally the window will end up unmaximized. Just don’t write code that crashes if not.
You can track maximization via the “window-state-event” signal on gtk.Widget