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
/*
		 * @see org.eclipse.swt.events.ShellAdapter#shellDeactivated(org.eclipse.swt.events.ShellEvent)
		 */
		public void shellDeactivated(ShellEvent e) {
			if (fMarkOccurrenceAnnotations && isActivePart())
				removeOccurrenceAnnotations();
		}
	}
	
	protected final static String MATCHING_BRACKETS=  PreferenceConstants.EDITOR_MATCHING_BRACKETS;
	
	protected final static String MATCHING_BRACKETS_COLOR=  PreferenceConstants.EDITOR_MATCHING_BRACKETS_COLOR;
	
	protected final static char[] BRACKETS= { '{', '}', '(', ')', '[', ']', '<', '>' };
	
	protected JavaOutlinePage fOutlinePage;
	
	protected String fOutlinerContextMenuId;
	/**
	 * The editor selection changed listener.
	 * 
	 * @since 3.0
	 */
	private EditorSelectionChangedListener fEditorSelectionChangedListener;
	
	protected AbstractSelectionChangedListener fOutlineSelectionChangedListener= new OutlineSelectionChangedListener();
	
	protected JavaPairMatcher fBracketMatcher= new JavaPairMatcher(BRACKETS);