title: TextBox LostFocus is not raised when clicking on certain other controls
body: <p>In the following simple WPF application a <code>TextBox</code> is set to update a property when the focus is lost from that control, like so</p>
  
  <pre><code>&lt;DockPanel&gt;
      &lt;ToolBar DockPanel.Dock="Top"&gt;
          &lt;Button&gt;Test&lt;/Button&gt;
      &lt;/ToolBar&gt;
      &lt;TextBox Text="{Binding MyString}" /&gt;
  &lt;/DockPanel&gt;
  
  public MainWindow()
  {
      InitializeComponent();
      DataContext = this;
  }
  
  public string MyString
  {
      get { return _myString; }
      set { _myString = value; }
  }
  </code></pre>
  
  <p>However when I run this application, enter some text in the text box and then click on the "Test" button my breakpoint on the <code>MyString</code> property is <strong>not</strong> raised, also any event handler for the <code>FocusLost</code> event is not raised either.  These events are only raised when focus is lost from the control via some other means (e.g. the window is closed).</p>
  
  <p>This is causing problems for us as in reality the "Test" button contains logic which relies on the <code>MyString</code> property being updated.</p>
  
  <p>How can I ensure that the <code>FocusLost</code> event is correctly raised and that the binding is updated as I click on the "Test" button?  It looks like the problem is somehow caused by the use of the <code>ToolBar</code>, as replacing the <code>ToolBar</code> with a standard button does not result in this behaviour.</p>