void onChange(ChangeEvent event)
false cancels the change. Note that if what you want to do is transform the user's input, for example,
automatically change separator characters to a standard separator character, you should implement
transformInput rather than using a combination of
change() and setValue() to accomplish the same thing. Returning false from
change is intended for
rejecting input entirely, such as typing invalid characters.
Note that if you ask the form for the current value in this handler, you will get the old value because the change has not yet been committed. The new value is available as a parameter to this method.
event- the event