main_page.js

Todos.mainPage = SC.Page.design({

  mainPane: SC.MainPane.design({
    childViews: 'middleView bottomView'.w(),

    middleView: SC.ScrollView.design({
      hasHorizontalScroller: NO,
      layout: { top: 36, bottom: 32, left: 0, right: 0 },
      backgroundColor: 'white',
      childViews: 'contentView'.w(),

      contentView: SC.ListView.design({
        contentBinding: 'Todos.tasksController.arrangedObjects',
        contentValueKey: 'description',
        contentCheckboxKey: 'isDone'
      })
    }),

    bottomView: SC.ToolbarView.design({
      childViews: 'summaryView'.w(),

      summaryView: SC.LabelView.design({
        valueBinding: 'Todos.tasksController.countSummary' //ADDED THIS
      })
    })
  })
});