title: Textbox text binding to Properties.Settings.Default.myString does not update myString
body: <p>I got a string <code>Properties.Settings.Default.myString</code> and two TextBoxes</p>
  
  <pre><code>&lt;TextBox x:Name="textBox1" Text="{Binding myString}"/&gt;
  &lt;TextBox x:Name="textBox2" Text="{Binding myString}"/&gt;
  </code></pre>
  
  <p>When I type text into <strong>textBox1</strong> and change Focus, the text in <strong>textBox2</strong> is updated with the text I just entered in <strong>textBox1</strong>.</p>
  
  <p>What confuses me is that <code>Properties.Settings.Default.myString</code> never updates with the text I enter in either of the TextBoxes. I did confirm this by inspecting <code>myString</code>in the debugger after changing it.</p>
  
  <p><strong>My question is, why this change in the textBox is not reflected in the bound variable <code>myString</code>?</strong></p>
  
  <p>Complete XAML (WPF-App):</p>
  
  <pre><code>&lt;Window
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
      xmlns:local="clr-namespace:textBoxDataBinding"
      xmlns:Properties="clr-namespace:textBoxDataBinding.Properties" x:Class="textBoxDataBinding.MainWindow"
  
      mc:Ignorable="d"
      Title="MainWindow" Height="212" Width="318"&gt;
  &lt;Window.DataContext&gt;
      &lt;Properties:Settings/&gt;
  &lt;/Window.DataContext&gt;
  &lt;Grid&gt;
  
      &lt;TextBox x:Name="textBox1" Text="{Binding myString}"/&gt;
      &lt;TextBox x:Name="textBox2" Text="{Binding myString}"/&gt;
  
      &lt;!-- Button does: textBlock.Text = Properties.Settings.Default.myString; --&gt;
      &lt;Button x:Name="button1" Content="Button" HorizontalAlignment="Left" Margin="10,157,0,0" VerticalAlignment="Top" Width="75" Click="button1_Click"/&gt;
      &lt;TextBlock x:Name="textBlock" HorizontalAlignment="Left" Margin="90,161,0,0" TextWrapping="Wrap" Text="TextBlock" VerticalAlignment="Top"/&gt;
  &lt;/Grid&gt;
  </code></pre>
  
  <p></p>