Set onAction handler for the browsable directory component
FileChoosers now remember the latest directory

Annotated method wasn't discovered.
Validation on Enter key made optional.

validate method doesn't make the validation state NOT_VALIDATED prior to
validation. NOT_VALIDATED state is set only when text of the field
changes. This avoid to trigger a VALID-NOT_VALIDATED-VALID chain every
time the validate() method is called which was in practice triggering
the state change listeners everytime the validate() was called, even if
the state wasn't actually changed.