public class ActionBar : Widget, Accessible, Buildable, ConstraintTarget
`GtkActionBar` is designed to present contextual actions.
![An example GtkActionBar](action-bar.png)
It is expected to be displayed below the content and expand horizontally to fill the area.
It allows placing children at the start or the end. In addition, it contains an internal centered box which is centered with respect to the full width of the box, even if the children at either side take up different amounts of space.
`GtkActionBar` has a single CSS node with name actionbar.