title: DevExpress eXpressApp Framework (XAF) - Extension property with drop-down list
body: <p>I'm trying to add an extension property to the model column that allows to select value from the drop-down list. So when I open Model Editor and choose some column in ListView I will be able to select value from the list for this extension property.</p>
  
  <p>I have created interface for property and registered it.</p>
  
  <pre><code>public interface IModelExDatabaseColumn : IModelColumn
  {
     [Category("Data")]
     [Required]
     string DatabaseColumn { get; set; }
  }
  
  public override void ExtendModelInterfaces(ModelInterfaceExtenders extenders)
  {
     base.ExtendModelInterfaces(extenders);
     extenders.Add&lt;IModelColumn, IModelExDatabaseColumn&gt;();
  }
  </code></pre>
  
  <p>Now it is visible in properties. How can I add drop-down list to it with some string values which generates in code?</p>