Bug 80429 [Preferences] [Dialogs] FieldEditors should relax requirements to support DialogPages
bundles/org.eclipse.jface/src/org/eclipse/jface/preference/FieldEditor.java
* one of this field editor's boolean-valued properties. Does nothing
     * if the old and new values are the same.
     *
     * @param property the field editor property name, 
     *   such as <code>VALUE</code> or <code>IS_VALID</code>
     * @param oldValue the old value
     * @param newValue the new value
     */
    protected void fireStateChanged(String property, boolean oldValue,
            boolean newValue) {
        if (oldValue == newValue)
            return;
        fireValueChanged(property, new Boolean(oldValue), new Boolean(newValue));
    }
    /**
     * Informs this field editor's listener, if it has one, about a change to
     * one of this field editor's properties.
     *
     * @param property the field editor property name, 
     *   such as <code>VALUE</code> or <code>IS_VALID</code>
     * @param oldValue the old value object, or <code>null</code>
     * @param newValue the new value, or <code>null</code>
     */
    protected void fireValueChanged(String property, Object oldValue,
            Object newValue) {
        if (propertyChangeListener == null)
            return;
        propertyChangeListener.propertyChange(new PropertyChangeEvent(this,
                property, oldValue, newValue));
    }