title: Does the GroupBox Header in WPF swallow mouse-clicks?
body: <p>Have a look at this very simple example WPF program:</p>
  
  <pre><code>&lt;Window x:Class="WpfApplication1.Window1"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      Title="Window1" Height="300" Width="300"&gt;
  
      &lt;GroupBox&gt;
          &lt;GroupBox.Header&gt;
              &lt;CheckBox Content="Click Here"/&gt;
          &lt;/GroupBox.Header&gt;
      &lt;/GroupBox&gt;
  &lt;/Window&gt;
  </code></pre>
  
  <p>So I have a GroupBox whose header is a CheckBox. We've all done something like this - typically you bind the content of the GroupBox in such a way that it's disabled when the CheckBox is unchecked.</p>
  
  <p>However, when I run this application and click on the CheckBox, I've found that sometimes my mouse clicks are swallowed and the CheckBox's status doesn't change. If I'm right, it's when I click on the exact row of pixels that the GroupBox's top border sits on.</p>
  
  <p>Can someone duplicate this? Why would this occur, and is there a way around it?</p>
  
  <p>Edit: Setting the GroupBox's BorderThickness to 0 solves the problem, but obviously it removes the border, so it doesn't look like a GroupBox anymore.</p>