The static trait change listeners *_changed (not _anytrait_changed) uses on_trait_change internally so we need to replace those methods to use observe instead. We need to rename the methods to ensure that traits on_trait_change doesn't use them by default - and then decorate them with the observe decorator.
The static trait change listeners
*_changed(not_anytrait_changed) useson_trait_changeinternally so we need to replace those methods to useobserveinstead. We need to rename the methods to ensure that traitson_trait_changedoesn't use them by default - and then decorate them with theobservedecorator.