gistfile1.cs

DevExpress eXpressApp Framework (XAF) - Extension property with drop-down list
public interface IModelExDatabaseColumn : IModelColumn
{
   [Category("Data")]
   [Required]
   string DatabaseColumn { get; set; }
}

public override void ExtendModelInterfaces(ModelInterfaceExtenders extenders)
{
   base.ExtendModelInterfaces(extenders);
   extenders.Add<IModelColumn, IModelExDatabaseColumn>();
}