The ButtonWidget documentation refers to a "state" attribute, but this
should probably be "set". The name "state" appears to be an artifact
from when the setTitle, setField, and setIndex attributes were added to
the widget; at one time they were called stateTitle and so on, and then
they were renamed to setTitle instead, but not every instance of "state"
was found and renamed to "set". This is one such instance, now fixed.
d8d88c67e3