GtkDialog::add_action_widget
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.