title: Using DropdownListFor ignoring the "selected" value I've set in the model
body: <p>Here is the controller code:</p>
  
  <pre><code>EfCategoriaRepository efCategoriaRepository = new EfCategoriaRepository();
  model.Categoria= new List&lt;SelectListItem&gt;();
  
  foreach (var categoria in efCategoriaRepository.FindAllCategorias())
  {
      model.Categoria.Add(new SelectListItem {
          Text = categoria.Nombre, 
          Value = categoria.CategoriaId.ToString(), 
          Selected = producto.CategoriaId == categoria.CategoriaId
      });
  }
  </code></pre>
  
  <p>Using the debugger, I can confirm that the correct value is being set to "Selected = True".</p>
  
  <p>My model:</p>
  
  <pre><code>public class ProductoModel
  {
      public int ProductoId { get; set; }
  
      public int CategoriaId { get; set; }
      public List&lt;SelectListItem&gt; Categoria { get; set; }
  
      [Required]
      public string Nombre { get; set; }
  
      [Required]
      public string Titulo { get; set; }
  
      [Required]
      [AllowHtml]
      public string Descripcion { get; set; }
  
      [Required]
      [AllowHtml]
      public string Caracteristicas { get; set; }
  
      [Required]
      [DisplayName("Precio - Categoria 1")]
      public decimal PrecioCatUno { get; set; }
  
      [Required]
      [DisplayName("Precio - Categoria 2")]
      public decimal PrecioCatDos { get; set; }
  
      [Required]
      [DisplayName("Precio - Categoria 3")]
      public decimal PrecioCatTres { get; set; }
  }
  </code></pre>
  
  <p>In my editor template:</p>
  
  <pre><code>&lt;div class="input-field"&gt;
      @Html.LabelFor(m =&gt; m.Categoria)
      @Html.DropDownListFor(model =&gt; model.CategoriaId, Model.Categoria)
  &lt;/div&gt;
  </code></pre>
  
  <p>Anybody know why the correct dropdown value isn't being selected despite the fact that I have set "selected" to true on the correct value?</p>