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
getSite().getPage().removePartListener(fPartListener);
			getSite().getPage().bringToTop(editorPart);
			EditorUtility.revealInEditor(editorPart, (IJavaElement) elem);
			getSite().getPage().addPartListener(fPartListener);
		}
	}
	
	private Display getDisplay() {
		if (fPagebook != null && !fPagebook.isDisposed()) {
			return fPagebook.getDisplay();
		}
		return null;
	}		
	
	private boolean isChildVisible(Composite pb, Control child) {
		Control[] children= pb.getChildren();
		for (int i= 0; i < children.length; i++) {
			if (children[i] == child && children[i].isVisible())
				return true;
		}
		return false;
	}
	
	private void updateTitle() {
		String viewerTitle= getCurrentViewer().getTitle();
		
		String tooltip;
		String title;
		if (fInputElement != null) {
			String[] args= new String[] { viewerTitle, JavaElementLabels.getElementLabel(fInputElement, JavaElementLabels.ALL_DEFAULT) };