Bug 117071 MembersOrderPreferenceCache leaking a propertyChangeListener
20051109 org.eclipse.jdt.ui.PreferenceConstants#initializeDefaultValues adds a listener to JDT UI preference store but this is not deleted before shutdown.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/PreferenceConstants.java
* </p>
	 * 
	 * @since 3.0
	 */
	public final static String SPELLING_LOCALE= ISpellCheckPreferenceKeys.SPELLING_LOCALE;
	/**
	 * A named preference that controls the number of proposals offered during
	 * spell-checking.
	 * <p>
	 * Value is of type <code>Integer</code>.
	 * </p>
	 * 
	 * @since 3.0
	 */
	public final static String SPELLING_PROPOSAL_THRESHOLD= ISpellCheckPreferenceKeys.SPELLING_PROPOSAL_THRESHOLD;
	/**
	 * A named preference that specifies the workspace user dictionary.
	 * <p>
	 * Value is of type <code>Integer</code>.
	 * </p>
	 * 
	 * @since 3.0
	 */
	public final static String SPELLING_USER_DICTIONARY= ISpellCheckPreferenceKeys.SPELLING_USER_DICTIONARY;
	/**
	 * A named preference that specifies whether spelling dictionaries are available to content assist.
	 * <p>
	 * Value is of type <code>Boolean</code>.
	 * </p>
	 *