code: protected boolean compareValues(Object previous, Object value) {
  		if (previous instanceof String && value instanceof Double) {
  			previous = Double.valueOf((String) previous);
  		}
  		return super.compareValues(previous, value);
  	}
docs: <p>
  Return <code>true</code> if the new value is different from the previous
  value. First compare the two values by passing <em>value</em> to the
  <code>equals</code> method on argument <em>previous</em>. If that method
  returns <code>true</code>, return <code>true</code>. If that method returns
  <code>false</code>, and both arguments implement
  <code>java.lang.Comparable</code>, compare the two values by passing
  <em>value</em> to the <code>compareTo</code> method on argument
  <em>previous</em>. Return <code>true</code> if this method returns
  <code>0</code>, <code>false</code> otherwise.
  </p>
  
  @param previous
  old value of this component (if any)
  @param value
  new value of this component (if any)