Javadoc
A Log4J Appender that creates dialogs in order to "log" messages.
Like all Log4J loggers, this logger can be set to report only messages above
a certain threshold using setThreshold(). The default threshold is WARN.
Only one dialog is shown at any single time: the user has to close it before
getting the next. The display of message dialogs is controlled by an
independent thread, so that the code that reports a message does not have to
wait for the user to close dialogs. Incoming events are queued and processed
in order.
For events of type ElkMessage (rather than plain String), the appender allows
to filter by message type, that is, it offers the user the option to not show
such messages again. Here, "such messages" means messages of the same message
type.