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
for (int i= 0; i < fAllViewers.length; i++) {
			fAllViewers[i].setMemberFilter(memberFilter);
		}
	}	
	
	private IType getSelectableType(IJavaElement elem) {
		if (elem.getElementType() != IJavaElement.TYPE) {
			return null; 
		} else {
			return (IType) elem;
		}
	}
	
	private void internalSelectType(IMember elem, boolean reveal) {	
		TypeHierarchyViewer viewer= getCurrentViewer();
		viewer.removeSelectionChangedListener(fSelectionChangedListener);
		viewer.setSelection(elem != null ? new StructuredSelection(elem) : StructuredSelection.EMPTY, reveal);
		viewer.addSelectionChangedListener(fSelectionChangedListener);
	}
		
	/**
	 * When the input changed or the hierarchy pane becomes visible,
	 * <code>updateHierarchyViewer<code> brings up the correct view and refreshes
	 * the current tree
	 */
	private void updateHierarchyViewer(final boolean doExpand) {
		if (fInputElement == null) {
			fPagebook.showPage(fNoHierarchyShownLabel);
		} else {
			if (getCurrentViewer().containsElements() != null) {