Creating an Adjustment
The Gtk::Adjustment constructor is as follows:
Gtk::Adjustment(float value, float lower, float upper, float step_increment = 1, float page_increment = 10, float page_size = 0);
The value argument is the initial value of the adjustment, usually corresponding to the topmost or leftmost position of an adjustable widget. The lower and upper arguments specifies the possible range of values which the adjustment can hold. The step_increment argument specifies the smaller of the two increments by which the user can change the value, while the page_increment is the larger one. The page_size argument usually corresponds somehow to the visible area of a panning widget. The upper argument is used to represent the bottom most or right most coordinate in a panning widget's child.