title: Implicit theme error:The property 'Content' was not found in type 'System.Windows.Controls.Control'
body: <p>I have got an error while trying to upgrade our large project to SL4.
  I didn't write the original theme and my theme knowlege isn't great.
  In my demo app I have a Label and a LabelHeader(which i have created and is just a derived class from Label with DefaultStyleKey = typeof(LabelHeader);<br>
  I am styling the LabelHeader like this:</p>
  
  <pre><code> &lt;Style TargetType="themeControls:LabelHeader"&gt;
      &lt;Setter Property="Template"&gt;
          &lt;Setter.Value&gt;
              &lt;ControlTemplate&gt;
                  &lt;DataInput:Label 
                      FontSize="{TemplateBinding FontSize}" 
                      FontFamily="{TemplateBinding FontFamily}" 
                      Foreground="{TemplateBinding Foreground}" 
                      Content="{TemplateBinding  Content}"/&gt;
              &lt;/ControlTemplate&gt;
          &lt;/Setter.Value&gt;
      &lt;/Setter&gt;
      &lt;Setter Property="FontFamily" Value="Tahoma"/&gt;
      &lt;Setter Property="FontSize" Value="20"/&gt;
      &lt;Setter Property="Foreground" Value="Red"/&gt;
  &lt;/Style&gt;
  </code></pre>
  
  <p>This works in SL3 but in SL4 I get:</p>
  
  <p>Error: Unhandled Error in Silverlight Application 
  Code: 2500<br>
  Category: ParserError<br>
  Message: The property 'Content' was not found in type 'System.Windows.Controls.Control'.<br>
  File:<br>
  Line: 9<br>
  Position: 168   </p>
  
  <p>If I change this:
  Content="{TemplateBinding  Content}"
  to
  Content="XXX"
  Then there is no error but , of course, I get XXX in my label rather than the content I set in XAML on the page</p>
  
  <p>Any ideas how I can get this working?</p>
  
  <p>Demo project here:</p>
  
  <p><a href="http://walkersretreat.co.nz/files/ThemeIssue.zip" rel="noreferrer">http://walkersretreat.co.nz/files/ThemeIssue.zip</a></p>
  
  <p>(Apologies for reposting, I have so far got no answers over here: <a href="http://forums.silverlight.net/forums/p/183380/415930.aspx#415930" rel="noreferrer">http://forums.silverlight.net/forums/p/183380/415930.aspx#415930</a>)</p>
  
  <p>EDIT The answer provided looks like it will work. An issue has been opened for this issue here: 
  <a href="https://connect.microsoft.com/VisualStudio/feedback/details/561183" rel="noreferrer">https://connect.microsoft.com/VisualStudio/feedback/details/561183</a> </p>
  
  <p>vote if you think this is important!</p>