Bug 28575 Hierarchy view updates items twice [type hierarchy]
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/typehierarchy/TypeHierarchyViewPart.java
fIsEnableMemberFilter= false;
			if (!fInputElement.equals(prevInput)) {
				updateHierarchyViewer();
			}
			IType root= getSelectableType(fInputElement);
			internalSelectType(root, true);
			updateMethodViewer(root);
			updateToolbarButtons();
			updateTitle();
			enableMemberFilter(false);
		}
	}
	
	private void clearInput() {
		fInputElement= null;
		fHierarchyLifeCycle.freeHierarchy();
		
		updateHierarchyViewer();
		updateToolbarButtons();
	}
	/*
	 * @see IWorbenchPart#setFocus
	 */	
	public void setFocus() {
		fPagebook.setFocus();
	}
	/*
	 * @see IWorkbenchPart#dispose
	 */	
	public void dispose() {