title: WindowsFormsHost steals focus on activating application even activating by application's other wpf form
body: <p>To Reproduce my case (.net 4.0)  </p>
  
  <ol>
  <li>Create a WPF Application (MainWindow.xaml)</li>
  <li>Add a Winform user control that contains a textbox (UserConrol1.cs - Winform)</li>
  <li>Put UserControl1 into MainWindow.xaml with windowsformshost</li>
  <li>Add another WPF Window that contains a textbox(wpf) to project (Window1.xaml)</li>
  <li>Create and Show Window1 after MainWindow InitializeComponent </li>
  </ol>
  
  <p>Your project is ready, </p>
  
  <ol>
  <li>Run Project and set textbox focused in MainWindow.xaml (that in WindowsFormsHost)</li>
  <li>Deactivate your application by opening a window  (Windows file explorer ,notepad, winamp etc.)</li>
  <li>Try to write in textbox that in Window1 window by clicking textbox with mouse</li>
  </ol>
  
  <p>And you will see that you can't set focus on textbox in Window1 because MainWindow Texbox( in winformshost will steal your focus on you application got activating)</p>
  
  <p>Any idea?</p>
  
  <p>MainWindow.xaml</p>
  
  <pre><code>&lt;Window x:Class="WinFormsHostFocusProblem.MainWindow"
          xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
          xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
          xmlns:local="clr-namespace:WinFormsHostFocusProblem"
          xmlns:my="clr-namespace:System.Windows.Forms.Integration;assembly=WindowsFormsIntegration"
          Title="MainWindow" Height="350" Width="525"&gt;
      &lt;Grid&gt;
        &lt;my:WindowsFormsHost  Focusable="False"  &gt;
           &lt;local:UserControl1&gt;
  
           &lt;/local:UserControl1&gt;
        &lt;/my:WindowsFormsHost&gt;
  
     &lt;/Grid&gt;
  &lt;/Window&gt;
  </code></pre>
  
  <p>MainWindow.xaml.cs</p>
  
  <pre><code>namespace WinFormsHostFocusProblem
  {
     public partial class MainWindow : Window
     {
        public MainWindow()
        {
           InitializeComponent();
           Window1 window1 = new Window1();
           window1.Show();
        }
     }
  }
  </code></pre>
  
  <p>Window1.xaml</p>
  
  <pre><code>&lt;Window x:Class="WinFormsHostFocusProblem.Window1"
          xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
          xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
          xmlns:local="clr-namespace:WinFormsHostFocusProblem"
          xmlns:my="clr-namespace:System.Windows.Forms.Integration;assembly=WindowsFormsIntegration"
          SizeToContent="WidthAndHeight" 
          ResizeMode="NoResize"
  
          Topmost="True"
          Title="Window1" Height="300" Width="300" Background="Red"&gt;
      &lt;Grid&gt;
        &lt;TextBox Height="25"&gt;asd&lt;/TextBox&gt;
     &lt;/Grid&gt;
  &lt;/Window&gt;
  </code></pre>
  
  <p>Window1.xaml.cs</p>
  
  <pre><code>namespace WinFormsHostFocusProblem
  {
     public partial class Window1 : Window
     {
        public Window1()
        {
           InitializeComponent();
        }
     }
  }
  </code></pre>