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/internal/ui/JavaPlugin.java
fCompilationUnitDocumentProvider.shutdown();
				fCompilationUnitDocumentProvider= null;
			}
					
			if (fJavaTextTools != null) {
				fJavaTextTools.dispose();
				fJavaTextTools= null;
			}
			
			if (fTypeFilter != null) {
				fTypeFilter.dispose();
				fTypeFilter= null;
			}
			
			if (fContentAssistHistory != null) {
				ContentAssistHistory.store(fContentAssistHistory, getPluginPreferences(), PreferenceConstants.CODEASSIST_LRU_HISTORY);
				fContentAssistHistory= null;
			}
			
			uninstallPreferenceStoreBackwardsCompatibility();
			TypeInfoHistory.shutdown();
		} finally {	
			super.stop(context);
		}
	}
		
	private IWorkbenchPage internalGetActivePage() {
		IWorkbenchWindow window= getWorkbench().getActiveWorkbenchWindow();
		if (window == null)
			return null;