public class Adjustment : InitiallyUnowned
`GtkAdjustment` is a model for a numeric value.
The `GtkAdjustment` has an associated lower and upper bound. It also contains step and page increments, and a page size.
Adjustments are used within several GTK widgets, including [class@Gtk.SpinButton], [class@Gtk.Viewport], [class@Gtk.Scrollbar] and [ class@Gtk.Scale].
The `GtkAdjustment` object does not update the value itself. Instead it is left up to the owner of the `GtkAdjustment` to control the value.