void add_action_widget(GtkWidget child, int response_id);

Use this method to add an activatable widget to the action_area of the dialog. The response ID to be generated when the widget is activated is passed as a parameter to the method. The widget is appended to the end of the dialog's action area.

Only activatable widgets may be added using this method. To add a non-activatable widget, use the add method on the action_area property of GtkDialog.