looking for complete example with BufferingForwardingAppender

[Chris Harrington-5]

Hi,
I would like my RollingFileAppender to log the last 10 messages at any level
when there is a message at the error level.

I am trying to use the BufferingForwardingAppender for this purpose, but
can't figure out the right levels/thresholds to have it behave properly.
Is this even possible? Do I need to have a separate RollingFileAppender
separate from my main log?
 
Thanks,
Chris