org.jboss.logmanager.formatters.PatternFormatter does not support "truncate from the beginning" as log4j patterns do
(see http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/PatternLayout.html)

e.g. in log4j the format "%30.30c" outputs a fixed length category (30 characters) and truncates the category from the beginning if it's longer than 30 characters (especially for the category this is a reasonable choice, because the beginning of the category - which is mostly a package name - is always the same and therefore not menaingful)

logmanager truncates at the end - so please add support for "truncate from the beginning"