Bug 81983 [preferences] Disabling and enabling folding on small file takes forever
3.1 M4 Using enable/disable folding on a small CU takes forever. This is caused by the recent change to apply the preference to all Java editors. In another (hidden) window (Debug) I had StyledText open which (understandably) took long to react on the preference change. Non-visible editor's should not react to this change until they become visible.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/JavaEditor.java
private Map fOptions;
		
		private IPreferenceStore fMockupPreferenceStore;
		
		private IPropertyChangeEventFilter fFilter;
		
		/**
		 * Initialize with the given options.
		 * 
		 * @param options The options to wrap
		 * @param mockupPreferenceStore the mock-up preference store
		 * @param filter the property change filter
		 */
		public OptionsAdapter(Map options, IPreferenceStore mockupPreferenceStore, IPropertyChangeEventFilter filter) {
			fMockupPreferenceStore= mockupPreferenceStore;
			fOptions= options;
			setFilter(filter);
		}
		/**
		 * {@inheritDoc}
		 */
		public void addPropertyChangeListener(IPropertyChangeListener listener) {
			if (fListeners.size() == 0)
				fMockupPreferenceStore.addPropertyChangeListener(fListener);
			fListeners.add(listener);
		}
		/**
		 * {@inheritDoc}
		 */
		public void removePropertyChangeListener(IPropertyChangeListener listener) {