Abstract class for a variety of components that render some variation of a text field. Most of the hooks for user input validation are in this class.
In particular, all subclasses support the "toclient" and "parseclient" events. These two events allow the normal {@link Translator} (specified by the translate parameter, but often automatically derived by Tapestry) to beaugmented.
If the component container (i.e., the page) provides an event handler method for the "toclient" event, and that handler returns a non-null string, that will be the string value sent to the client. The context passed to the event handler method is t he current value of the value parameter.
Likewise, on a form submit, the "parseclient" event handler method will be passed the string provided by the client, and may provide a non-null value as the parsed value. Returning null allows the normal translator to operate. The event handler may also throw {@link org.apache.tapestry5.ValidationException}.