Bug 32384 Cannot open type hierarchy after a cancel
JUnit setup 1) open the type hierarchy on TestCase 2) press F4 on Object 3) cancel in progress bar 4) press F4 on Object again ->nothing happens
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/typehierarchy/TypeHierarchyViewPart.java
trackedViewers[i]= fAllViewers[i];
		}
		trackedViewers[nHierarchyViewers]= fMethodsViewer;
		fSelectionProviderMediator= new SelectionProviderMediator(trackedViewers);
		IStatusLineManager slManager= getViewSite().getActionBars().getStatusLineManager();
		fSelectionProviderMediator.addSelectionChangedListener(new StatusBarUpdater(slManager));
		
		getSite().setSelectionProvider(fSelectionProviderMediator);
		getSite().getPage().addPartListener(fPartListener);
		
		IJavaElement input= determineInputElement();
		if (fMemento != null) {
			restoreState(fMemento, input);
		} else if (input != null) {
			setInputElement(input);
		} else {
			setViewerVisibility(false);
		}
		WorkbenchHelp.setHelp(fPagebook, IJavaHelpContextIds.TYPE_HIERARCHY_VIEW);
		
		fActionGroups= new CompositeActionGroup(new ActionGroup[] {
				new NewWizardsActionGroup(this.getSite()),
				new OpenEditorActionGroup(this), 
				new OpenViewActionGroup(this), 
				fCCPActionGroup= new CCPActionGroup(this), 
				new RefactorActionGroup(this),
				new GenerateActionGroup(this),
				new JavaSearchActionGroup(this)});
		
		fActionGroups.fillActionBars(actionBars);