title: Placing more than one element into a GroupBox in WPF
body: <p>I'm trying to make a GroupBox with a few (radio)buttons in it. But in the samples i'm using checkbox.</p>
  
  <pre><code>&lt;GroupBox Header="Aðgerðir" HorizontalAlignment="Left" VerticalAlignment="Bottom" Margin="270,0,0,178" Height="106" Width="176"&gt;
      &lt;CheckBox Content="CheckBox" HorizontalAlignment="Left" VerticalAlignment="Top"/&gt;
      &lt;CheckBox Content="CheckBox" HorizontalAlignment="Left" VerticalAlignment="Bottom"/&gt;
  &lt;/GroupBox&gt;
  </code></pre>
  
  <p>The above does not work and visual studio says "Invalid Markup".</p>
  
  <p>This here works fine though</p>
  
  <pre><code>&lt;GroupBox Header="Aðgerðir" HorizontalAlignment="Left" VerticalAlignment="Bottom" Margin="270,0,0,178" Height="106" Width="176"&gt;
      &lt;CheckBox Content="CheckBox" HorizontalAlignment="Left" VerticalAlignment="Top"/&gt;
  &lt;/GroupBox&gt;
  </code></pre>
  
  <p>I don't get it. It says "Content can only be set once" if i run the debugger, but erasing the Content part of the checkbox seems to have no effect.</p>