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
* 
	 * @deprecated since 3.1, use {@link org.eclipse.ui.texteditor.spelling.SpellingService#PREFERENCE_SPELLING_ENABLED}
	 *             and {@link org.eclipse.ui.texteditor.spelling.SpellingService#PREFERENCE_SPELLING_ENGINE}
	 * @since 3.0
	 */
	public final static String SPELLING_CHECK_SPELLING= "spelling_check_spelling"; 
	/**
	 * A named preference that controls whether words containing digits should
	 * be skipped during spell-checking.
	 * <p>
	 * Value is of type <code>Boolean</code>.
	 * </p>
	 * 
	 * @since 3.0
	 */
	public final static String SPELLING_IGNORE_DIGITS= ISpellCheckPreferenceKeys.SPELLING_IGNORE_DIGITS;
	/**
	 * A named preference that controls whether mixed case words should be
	 * skipped during spell-checking.
	 * <p>
	 * Value is of type <code>Boolean</code>.
	 * </p>
	 * 
	 * @since 3.0
	 */
	public final static String SPELLING_IGNORE_MIXED= ISpellCheckPreferenceKeys.SPELLING_IGNORE_MIXED;
	/**
	 * A named preference that controls whether sentence capitalization should
	 * be ignored during spell-checking.
	 * <p>