Ability to set properties on PersistenceManager

It would be desirable to be able to set properties on the PersistenceManager, so as to be able to configure/change behaviour for a PM. Currently the PM is generated with particular configuration (from the PMF) and allows specific options to be set. But what about vendor extensions ? Having a general setProperty/getProperty/getSupportedProperties would be useful, and could also encompass the existing detachAllOnCommit, IgnoreCache, etc settings.