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
if (types.size() == 1) {
					fSelectedType= (IType) types.get(0);
					updateMethodViewer(fSelectedType);
				} else if (types.size() == 0) {
					
				}
				if (nSelected == 1) {
					revealElementInEditor(selected.get(0), getCurrentViewer());
				}
			} else {
				fSelectedType= null;
				updateMethodViewer(null);
			}
		}
	}
	
	private void revealElementInEditor(Object elem, Viewer originViewer) {
		
		
		
		if (getSite().getPage().getActivePart() != this) {
			return;
		}
		
		if (fSelectionProviderMediator.getViewerInFocus() != originViewer) {
			return;
		}
		
		IEditorPart editorPart= EditorUtility.isOpenInEditor(elem);
		if (editorPart != null && (elem instanceof IJavaElement)) {