title: I have bind numbers to CombBox. I want change value comboBox and textBox changed value
body: <p>I want change number from <code>ComboBox</code> and change value in <code>TextBox</code>.</p>
  
  <p>(For example I have number =2 and content at "lblblblb" ofc. this is in <code>ObservableCollection&lt;string&gt;</code>, so I to call <code>ContentWithListView[SelectNumberStep]</code>)</p>
  
  <p><strong>ReadPage.xaml</strong></p>
  
  <pre><code>&lt;TextBox HorizontalAlignment="Left" Margin="580,154,0,0" 
   TextWrapping="Wrap" Text="{Binding ContentWithListView[SelectNumberStep],Mode=TwoWay}"
   VerticalAlignment="Top" Width="725" Height="82"/&gt;
  
  &lt;ComboBox HorizontalAlignment="Left" Margin="440,154,0,0" 
   ItemsSource="{Binding NumberStep,Mode=TwoWay}" 
   SelectedItem="{Binding SelectNumberStep,Mode=TwoWay}" 
   VerticalAlignment="Top" Width="95" Height="77" /&gt;
  </code></pre>
  
  <p>How I change content in TextBox from CombBox numbers?</p>
  
  <p><strong>ReadViewModel.cs</strong></p>
  
  <pre><code>private ObservableCollection&lt;string&gt; contentWithListView;
  public ObservableCollection&lt;string&gt; ContentWithListView
  {
      get
      {
          return this.contentWithListView;
      }
  
      set
      {
          this.contentWithListView = value;
      }
  }
  
  private ObservableCollection&lt;int&gt; stepNumber;
  public ObservableCollection&lt;int&gt; NumberStep
  {
      get
      {
          return this.stepNumber;
      }
  
      set
      {
          this.stepNumber = value;
      }
  }
  
  private int selectNumberStep;
  public int SelectNumberStep
  {
      get
      {
          return this.selectNumberStep;
      }
  
      set
      {
          this.selectNumberStep = value;    
      }
  }
  </code></pre>