The `GtkOrientable` interface is implemented by all widgets that can be oriented horizontally or vertically.
`GtkOrientable` is more flexible in that it allows the orientation to be changed at runtime, allowing the widgets to “flip”.
CSS nodes
`GtkWidget` types implementing the `GtkOrientable` interface will automatically acquire the `horizontal` or `vertical` CSS class
depending on the value of the [property@Gtk.Orientable:orientation] property.