title: TabItem LostFocus Event is not firing the first time
body: <p>I have a <code>TabControl</code> with two <code>TabItem</code>s. I have a <code>Thread</code> running in the first tab. When the first tab loses focus, I have to suspend the thread. But I have a small problem with the <code>LostFocus</code> event of the <code>TabItem</code>. The <code>LostFocus</code> event is not triggered the first time the <code>TabItem</code> loses focus, but the second time. Why is this and how do I make it fire the first time?</p>
  
  <p>The following is my xaml code:</p>
  
  <pre><code>&lt;Grid&gt;
      &lt;TabControl Name="tbc"&gt;
          &lt;TabItem Name="tabMain" Header="Main" GotFocus="tabMain_GotFocus" LostFocus="tabMain_LostFocus" &gt;
              &lt;uc:ucMain /&gt;
          &lt;/TabItem&gt;
          &lt;TabItem Name="tabExplorer" Header="Data Explorer"&gt;
              &lt;uc:ucExplorer /&gt;
          &lt;/TabItem&gt;
      &lt;/TabControl&gt;
  &lt;/Grid&gt;
  </code></pre>
  
  <p>In the above code, uc:ucMain is a <code>UserControl</code></p>