The GtkOrientable interface is implemented by all widgets that can be oriented horizontally or vertically. Historically, such widgets have been realized as subclasses of a common base class (e.g gtk.Box/gtk.HBox/gtk.VBox or gtk.Scale/gtk.HScale/gtk.VScale). GtkOrientable is more flexible in that it allows the orientation to be changed at runtime, allowing the widgets to “flip”.
Undocumented in source.