It would be nice if a property could make the existing ThresholdFilter act in the opposite way - so that it response with NEUTRAL to levels equal to or below the configured level, instead of equal to or above it. This would mean you could use two appenders with ThresholdFilters to split logging between error/warn on the one hand and info/debug/trace on the other, for instance.

A new property (perhaps "revers"?) could be created with a default value of false and it would be backward compatible.

(It's trivial to do yourself, of course, but it would be nice to have out of the box.)