A scrollbar needs a GtkAdjustment in order to operate. The values that you give to the adjustment object will depend on the situation where the scrollbar is intended to be used.

All scrollable widgets have their own adjustment object(s), and in most instances where you are most likely to need a horizontal scrollbar it is possible to create a handle for the widget's horizontal GtkAdjustment and assign that as the new scrollbar's adjustment object.

See also: GtkAdjustment, GtkVScrollbar.