title: Prism v4 Loading modules on demand with DirectoryModuleCatalog
body: <p>In my bootstrapper I have the following code to create my Directory ModuleCatalog</p>
  
  <pre><code>protected override IModuleCatalog CreateModuleCatalog()
  {
      DirectoryModuleCatalog catalog = new DirectoryModuleCatalog();
      catalog.ModulePath = @".\Modules";
      return catalog;
  }
  </code></pre>
  
  <p>but all my modules seem to be loading when the shell gets created. How can I load them on demand while still using the DirectoryModuleCatalog?</p>