GtkSpinButton::set_update_policy

There are only two possible settings for the spinbutton update policy. Setting it as GTK_UPDATE_IF_VALID prevents the current value from being changed where the newly entered value is outside the range determined by the underlying GtkAdjustment.

The default setting is GTK_UPDATE_ALWAYS, which allows the update to continue by replacing an invalid value with the value of the nearest range boundary.

Note that set_value() . overrides the update policy setting.