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
/**
			 * {@inheritDoc}
			 */
			public void propertyChange(PropertyChangeEvent event) {
				if (getFilter().isFiltered(event))
					return;
				
				if (event.getNewValue() == null)
					fOptions.remove(event.getProperty());
				else
					fOptions.put(event.getProperty(), event.getNewValue());
				
				firePropertyChangeEvent(event.getProperty(), event.getOldValue(), event.getNewValue());
			}
		}
		
		private ListenerList fListeners= new ListenerList();
		
		private IPropertyChangeListener fListener= new PropertyChangeListener();