function createApp(sessionsManager: NotebookSessionManager, specs: IKernelSpecIds): void {
  // Initialize the keymap manager with the bindings.
  let keymap = new KeymapManager();
  let useCapture = true;

  // Setup the keydown listener for the document.
  document.addEventListener('keydown', event => {
    keymap.processKeydownEvent(event);
  }, useCapture);

  const transformers = [
    new JavascriptRenderer(),
    new MarkdownRenderer(),
    new HTMLRenderer(),
    new ImageRenderer(),
    new SVGRenderer(),
    new LatexRenderer(),
    new TextRenderer()
  ];
  let renderers: MimeMap<IRenderer<Widget>> = {};
  let order: string[] = [];
  for (let t of transformers) {
    for (let m of t.mimetypes) {
      renderers[m] = t;
      order.push(m);
    }
  }
  let rendermime = new RenderMime<Widget>(renderers, order);

  let opener = {
    open: (widget: DocumentWrapper) => {
      // Do nothing for sibling widgets for now.
    }
  };

  let contentsManager = new ContentsManager();
  let docRegistry = new DocumentRegistry();
  let docManager = new DocumentManager(
    docRegistry, contentsManager, sessionsManager, specs, opener
  );
  let mFactory = new NotebookModelFactory();
  let clipboard = new MimeData();
  let wFactory = new NotebookWidgetFactory(rendermime, clipboard);
  docRegistry.registerModelFactory(mFactory);
  docRegistry.registerWidgetFactory(wFactory, {
    displayName: 'Notebook',
    modelName: 'notebook',
    fileExtensions: ['.ipynb'],
    defaultFor: ['.ipynb'],
    preferKernel: true,
    canStartKernel: true
  });

  let doc = docManager.open(NOTEBOOK);
  let nbWidget: NotebookPanel;
  doc.populated.connect((d, widget) => {
    nbWidget = widget as NotebookPanel;
  });

  let pModel = new StandardPaletteModel();
  let palette = new CommandPalette();
  palette.model = pModel;

  let panel = new SplitPanel();
  panel.id = 'main';
  panel.orientation = SplitPanel.Horizontal;
  panel.spacing = 0;
  SplitPanel.setStretch(palette, 0);
  panel.attach(document.body);
  panel.addChild(palette);
  panel.addChild(doc);
  SplitPanel.setStretch(doc, 1);
  window.onresize = () => panel.update();

  let saveHandler = () => nbWidget.context.save();
  let interruptHandler = () => {
    if (nbWidget.context.kernel) {
      nbWidget.context.kernel.interrupt();
    }
  };
  let restartHandler = () => nbWidget.restart();
  let switchHandler = () => {
    selectKernelForContext(nbWidget.context, nbWidget.node);
  };
  let runAdvanceHandler = () => {
    NotebookActions.runAndAdvance(nbWidget.content, nbWidget.context.kernel);
  };
  let editHandler = () => { nbWidget.content.mode = 'edit'; };
  let commandHandler = () => { nbWidget.content.mode = 'command'; };
  let codeHandler = () => {
    NotebookActions.changeCellType(nbWidget.content, 'code');
  };
  let markdownHandler = () => {
    NotebookActions.changeCellType(nbWidget.content, 'markdown');
  };
  let rawHandler = () => {
    NotebookActions.changeCellType(nbWidget.content, 'raw');
  };
  let selectBelowHandler = () => {
    NotebookActions.selectBelow(nbWidget.content);
//.........这里部分代码省略.........

function createApp(sessionsManager: NotebookSessionManager, specs: IKernelSpecIds): void {
  let contentsManager = new ContentsManager();
  let widgets: DocumentWidget[] = [];
  let activeWidget: DocumentWidget;

  let opener = {
    open: (widget: DocumentWidget) => {
      if (widgets.indexOf(widget) === -1) {
        dock.insertTabAfter(widget);
        widgets.push(widget);
      }
      dock.selectWidget(widget);
      activeWidget = widget;
      widget.disposed.connect((w: DocumentWidget) => {
        let index = widgets.indexOf(w);
        widgets.splice(index, 1);
      });
    }
  };

  let docRegistry = new DocumentRegistry();
  let docManager = new DocumentManager(
    docRegistry, contentsManager, sessionsManager, specs, opener
  );
  let mFactory = new TextModelFactory();
  let wFactory = new EditorWidgetFactory();
  docRegistry.registerModelFactory(mFactory);
  docRegistry.registerWidgetFactory(wFactory, {
    displayName: 'Editor',
    modelName: 'text',
    fileExtensions: ['.*'],
    defaultFor: ['.*'],
    preferKernel: false,
    canStartKernel: true
  });

  let fbModel = new FileBrowserModel(contentsManager, sessionsManager, specs);
  let fbWidget = new FileBrowserWidget(fbModel, docManager, opener);

  let panel = new SplitPanel();
  panel.id = 'main';
  panel.addChild(fbWidget);
  SplitPanel.setStretch(fbWidget, 0);
  let dock = new DockPanel();
  panel.addChild(dock);
  SplitPanel.setStretch(dock, 1);
  dock.spacing = 8;

  document.addEventListener('focus', event => {
    for (let i = 0; i < widgets.length; i++) {
      let widget = widgets[i];
      if (widget.node.contains(event.target as HTMLElement)) {
        activeWidget = widget;
        break;
      }
    }
  });

  let keymapManager = new KeymapManager();
  keymapManager.add([{
    sequence: ['Enter'],
    selector: '.jp-DirListing',
    handler: () => {
      fbWidget.open();
    }
  }, {
    sequence: ['Ctrl N'], // Add emacs keybinding for select next.
    selector: '.jp-DirListing',
    handler: () => {
      fbWidget.selectNext();
    }
  }, {
    sequence: ['Ctrl P'], // Add emacs keybinding for select previous.
    selector: '.jp-DirListing',
    handler: () => {
      fbWidget.selectPrevious();
    }
  }, {
    sequence: ['Accel S'],
    selector: '.jp-CodeMirrorWidget',
    handler: () => {
      activeWidget.context.save();
    }
  }]);

  window.addEventListener('keydown', (event) => {
    keymapManager.processKeydownEvent(event);
  });

  let contextMenu = new Menu([
    new MenuItem({
      text: '&Open',
      icon: 'fa fa-folder-open-o',
      shortcut: 'Ctrl+O',
      handler: () => { fbWidget.open(); }
    }),
    new MenuItem({
      text: '&Rename',
      icon: 'fa fa-edit',
      shortcut: 'Ctrl+R',
//.........这里部分代码省略.........