Clarity in a detail of the documentation could be improved

The documentation at https://developer.xfce.org/xfce4-panel/XfceArrowButton.html says "Since 4.8 it is also possible to [...] pack additional widgets in the button, using gtk_container_add()."

It would be more precise and thus more helpful to state "... pack an additional widget in the button, using gtk_container_add()."