JavaUIHelp.setHelp(this, IJavaHelpContextIds.CALL_HIERARCHY_VIEW);
    CallHierarchyViewer(Composite parent, CallHierarchyViewPart part) {        super(new Tree(parent, SWT.MULTI));        fPart = part;        getControl().setLayoutData(new GridData(GridData.FILL_BOTH));        setUseHashlookup(true);        setAutoExpandLevel(2);        fContentProvider = new CallHierarchyContentProvider(fPart);        setContentProvider(fContentProvider);        setLabelProvider(new CallHierarchyLabelProvider());        JavaUIHelp.setHelp(this, IJavaHelpContextIds.CALL_HIERARCHY_VIEW);        fOpen= new OpenLocationAction(part, part.getSite());        addOpenListener(new IOpenListener() {            public void open(OpenEvent event) {                fOpen.run();            }        });        clearViewer();    }