portmaster -- preserving added files?

[Gary Aitken]

Is portmaster supposed to retain files which it did not install when updating /
reinstalling a port?

For example, jave extensions are normally installed by placing a jar file in
  /usr/local/openjdk6/jre/lib/ext/

When reinstalling, these are wiped out.
At least I think that's what happened when I reinstalled.

Seems like they should be (at least optionally) retained?

Gary