Specifies the name of the action with which this widget should be associated.
If action_name is null then the widget will be unassociated from any previous action.
Usually this function is used when the widget is located (or will be located) within the hierarchy of a `GtkApplicationWindow`.
Names are of the form “win.save” or “app.quit” for actions on the containing [class@ApplicationWindow] or its associated [ class@Application], respectively. This is the same form used for actions in the [[email protected]] associated with the window.
| this |
a `GtkActionable` widget |
| action_name |
an action name |