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/TypeHierarchyLifeCycle.java
public TypeHierarchyLifeCycle(boolean isSuperTypesOnly) {
		fHierarchy= null;
		fInputElement= null;
		fIsSuperTypesOnly= isSuperTypesOnly;
		fChangeListeners= new ArrayList(2);
		fReconciled= false;
	}
	
	public ITypeHierarchy getHierarchy() {
		return fHierarchy;
	}
	
	public IJavaElement getInputElement() {
		return fInputElement;
	}
	
	
	public void freeHierarchy() {
		if (fHierarchy != null) {
			fHierarchy.removeTypeHierarchyChangedListener(this);
			JavaCore.removeElementChangedListener(this);
			fHierarchy= null;
			fInputElement= null;
		}
	}
	
	public void removeChangedListener(ITypeHierarchyLifeCycleListener listener) {
		fChangeListeners.remove(listener);
	}