= class Gtk::Scrollbar
The Gtk::Scrollbar widget is an abstract base class for Gtk::HScrollbar and Gtk::VScrollbar. It is not very useful in itself. 

The position of the thumb in a scrollbar is controlled by the scroll adjustments. See Gtk::Adjustment for the fields in an adjustment - for Gtk::Scrollbar, the "value" field represents the position of the scrollbar, which must be between the "lower" field and "upper - page_size." The "page_size" field represents the size of the visible scrollable area. The "step_increment" and "page_increment" fields are used when the user asks to step down (using the small stepper arrows) or page down (using for example the PageDown key). 

== Object Hierarchy
* Object
  * GLib::Instantiatable
    * GLib::Object
      * Gtk::Object
        * Gtk::Widget
          * Gtk::Range
            * Gtk::Scrollbar

== See Also
* Gtk::HScrollbar a horizontal scrollbar.
* Gtk::VScrollbar a vertical scrollbar.
* Gtk::Adjustment connects scrollbars to the widget being scrolled.
* Gtk::ScrolledWindow convenient widget for setting up scrolling.


- ((<Masao>))