GWT框架 tree节点只能选择一次！

[jfrankie]

只有刷新了 才能再选，但也是只能选择一次，再点其他，也还是加载不出来页面。
请大神帮忙看看。

public class TypeConfigPage extends ContentPanel {

	private static final IssueTypeProperties ISSUE_TYPE_PROPERTIES = GWT
			.create(IssueTypeProperties.class);
	private static final CarTypeProperties CAR_TYPE_PROPERTIES = GWT
			.create(CarTypeProperties.class);

	private SystemServiceAsync service;

	private Folder lastFolder;

	// 垂直组件
	 HorizontalLayoutContainer hlc = new HorizontalLayoutContainer();
	BorderLayoutContainer container = new BorderLayoutContainer();
	class KeyProvider implements ModelKeyProvider<Folder> {
		@Override
		public String getKey(Folder item) {
			return (item instanceof Folder ? "f-" : "m-")
					+ item.getId().toString();
		}
	}

	public TypeConfigPage(Folder folder, SystemServiceAsync systemServiceAsync) {
		this.service = systemServiceAsync;
		setHeadingText(folder.getName());
		ToolTipCreator.create(folder, getHeader(),
				"此页面主要配置一些系统基本信息,如<font color='red'>阿斯多夫</font>");

		 hlc.setScrollMode(ScrollMode.AUTO);
		
		 hlc.add(createLeftTree(), new HorizontalLayoutData(300, 1, new
		 Margins(
		 5, 5, 5, 5)));
		 hlc.add(craeteIssueTypeGrid(), new HorizontalLayoutData(1360, 1,
		 new Margins(5, 5, 5, 0)));

		 add(hlc);
	}

	private FramedPanel createLeftTree() {
		FramedPanel panel = new FramedPanel();
		panel.setHeadingText("选择类别");
		TreeStore<Folder> store = new TreeStore<Folder>(new KeyProvider());

		List<Folder> typelist = new ArrayList<Folder>();
		typelist.add(new Folder(
				"<i class='fa fa-star fa-lg light-blue'></i> 卡片操作类型", "",
				"", 1));
		typelist.add(new Folder(
				"<i class='fa fa-star fa-lg light-blue'></i> 车辆类型", "",
				"", 2));
		for (Folder base : typelist) {
			store.add(base);
		}

		final Tree<Folder, String> tree = new Tree<Folder, String>(store,
				new ValueProvider<Folder, String>() {

					@Override
					public String getValue(Folder object) {
						return object.getName();
					}

					@Override
					public void setValue(Folder object, String value) {
						
					}

					@Override
					public String getPath() {
						return "name";
					}
				});
		tree.setWidth(280);

		tree.getSelectionModel().setSelectionMode(SelectionMode.SINGLE);

		SelectionChangedHandler<Folder> ts = new SelectionChangedHandler<Folder>() {

			@Override
			public void onSelectionChanged(SelectionChangedEvent<Folder> event) {
				Folder f = (Folder) event.getSelection().get(0);
				if (f != lastFolder) {
					lastFolder = f;
					hlc.remove(1);
					if (f.getId() == 1) {
						hlc.add(craeteIssueTypeGrid(),
								new HorizontalLayoutData(1360, 1, new Margins(
										5, 5, 5, 0)));
					} else if (f.getId() == 2) {
						hlc.add(craeteCarTypeGrid(), new HorizontalLayoutData(
								1360, 1, new Margins(5, 5, 5, 0)));
					}
					hlc.forceLayout();
				}
			}

		};
		tree.getSelectionModel().addSelectionChangedHandler(ts);
		panel.add(tree);
		return panel;
	}