gtk:window-maximized (object)

object -- a gtk:window widget
maximized -- a boolean whether the window is maximized

The accessor for the maximized slot gets or sets whether the window is maximized. Setting this property is the equivalent of calling the gtk:window-maximize or gtk:window-unmaximize functions. Either operation is asynchronous, which means you will need to connect to the "notify" signal in order to know whether the operation was successful.