1. The inherited implementation of isLoggable()
always returns true. Logger should override this
to honor the minimum severity.

2. The notify() method does not check the severity.

I will attach a patch that seems to fix (1) and
(2). I noticed in NbErrorManager that there was
this implementation of isNotifiable:
    /** Honor configured min-severity levels, more
or less.
     * Actually bump up the effective severity of an 
     * exception by one.
     * Thus by default INFORMATIONAL stack traces are 
     * displayed, but not messages. By playing with
     * min log severity levels, you can get
     * both, or neither.
     * @see #24056
     */
    public boolean isNotifiable(int severity) {
        return isLoggable(severity + 1);
    }

I don't know if this is the desired behavior for
the MDR Logger or not. 

Sorry I didn't notice this earlier; my code was
previously using
setProperty("org.netbeans.lib.jmi.Logger.fileName",
"") to prevent messages from being displayed
altogether, so I wasn't affected by this problem
until I switched to more fine-grained message
reporting.