title: Cannot find resource dictionary in WPF application
body: <p>I'm in the process of building a WPF application and ran into an error when trying to reference a resource dictionary. Inside my WPF application project I have a folder called "Styles" to contain all the xaml style templates for my app:</p>
  
  <p><img src="https://i.stack.imgur.com/Rl7GJ.jpg" alt="VS2010 Solution Explorer"></p>
  
  <p>In my app.xaml file I have this:</p>
  
  <pre><code>&lt;Application.Resources&gt;
      &lt;ResourceDictionary&gt;
          &lt;ResourceDictionary.MergedDictionaries&gt;
              &lt;ResourceDictionary Source="Styles/MetroTheme.xaml" /&gt;
          &lt;/ResourceDictionary.MergedDictionaries&gt;
      &lt;/ResourceDictionary&gt;
  &lt;/Application.Resources&gt;
  </code></pre>
  
  <p>However, when I hover over the source property I get an error saying "An error occurred while finding the resource dictionary "Styles/MetroTheme.xaml". I can see the xaml file inside the folder both in Visual Studio and in the file system.</p>
  
  <p>I have also tried "/Styles/MetroTheme.xaml" and a pack uri for the source property, both with no success. Any idea why I'm getting this file not found error?</p>