title: Styles from generic.xaml are not applied
body: <p>I made a class library assembly in which I created custom controls, and I defined the default styles in the generic.xaml file.</p>
  
  <p>It seems this is a quite common problem, as long as many people are posting about it.
  However I couldn't find any useful answer for my case.</p>
  
  <ul>
  <li>the generic.xaml is in the Themes folder.</li>
  <li>the generix.xaml file Build Action is set to Page.</li>
  <li>the ThemeInfo is properly defined in my AssemblyInfo.cs.</li>
  </ul>
  
  <p>In my test application, if I manually merge the generic.xaml file from my custom controls assembly into the application App.xaml file like this:</p>
  
  <pre><code>&lt;Application.Resources&gt;
    &lt;ResourceDictionary&gt;
      &lt;ResourceDictionary.MergedDictionaries&gt;
        &lt;ResourceDictionary Source="/MyControlsAssembly;component/Themes/generic.xaml"/&gt;
      &lt;/ResourceDictionary.MergedDictionaries&gt;
    &lt;/ResourceDictionary&gt;
  &lt;/Application.Resources&gt;
  </code></pre>
  
  <p>then the custom controls are properly themed, but if I do not manually merge the generic.xaml, the controls appear with the default Windows theme.</p>
  
  <p>Could you please tell me what am I forgetting and/or doing wrong ?</p>
  
  <p>Additional info:</p>
  
  <ul>
  <li><p>My ThemeInfo assembly attribute is defined as follow:</p>
  
  <p><code>[assembly: ThemeInfo(ResourceDictionaryLocation.SourceAssembly, ResourceDictionaryLocation.SourceAssembly)]</code></p>
  
  <p>(Note: the result is just the same with any combination of parameters for the ThemeInfo attribute)</p></li>
  <li><p>There are two others .xaml files beside the generic.xaml file in the Themes folder.</p></li>
  <li>There is a subfolder in the Themes folder that itself contains another .xaml file.</li>
  </ul>