title: Label doesn't display "_" character
body: <p>My <code>Label.Content</code> in WPF doesn't  display the first occurrence  of "_" character. Why? </p>
  
  <pre><code>&lt;Window x:Class="WpfApplication3.MainWindow"
          xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
          xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
          Title="MainWindow" Height="148" Width="211"&gt;
      &lt;Grid&gt;
          &lt;Label Content="L_abel" Height="28" HorizontalAlignment="Left" Margin="37,31,0,0" Name="label1" VerticalAlignment="Top" /&gt;
      &lt;/Grid&gt;
  &lt;/Window&gt;
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/qrX6n.jpg" alt="enter image description here"></p>
  
  <p>When set <code>Label.Content ="L__abel"</code> :</p>
  
  <p><img src="https://i.stack.imgur.com/QSsPK.jpg" alt="enter image description here"></p>
  
  <p>There is no additional code in project.</p>