title: Property Grid Object failing on combo box selection but OK when combobox scrolled or double clicked
body: <p>I have a Property Grid in C#, loading up a 'PropertyAdapter' object (a basic wrapper around one of my objects displaying relevant properties with the appropriate tags)</p>
  
  <p>I have a TypeConverter on one of the properties (DataType, that returns an enumeration of possible values) as I want to limit the values available to the property grid to Decimal and Integer, with the 2 methods as follows</p>
  
  <pre><code>public override bool GetStandardValuesSupported(ITypeDescriptorContext context)
  {
      return true;
  }
  
  public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context)
  {
      return new StandardValuesCollection(new List&lt;Constants.DataTypes&gt;() { Constants.DataTypes.Decimal, Constants.DataTypes.Integer });
  }
  </code></pre>
  
  <p>This is displaying just as I want it on the property grid, and when I double click the property field in the property grid, it happily switches between Integer and Decimal. Similarily I can use the mouse wheel to scroll through the options in the property filed's combobox.</p>
  
  <p>If I however use the property field as a Combo Box and select a value from the drop-down, I get the standard property grid error box with the error:</p>
  
  <blockquote>
    <p>Object of type 'System.String' cannot
    be converted to type
    'Pelion.PM3.Utils.Constants+DataTypes'.</p>
  </blockquote>
  
  <p>I am assuming I can use the Converter overrides in the Type converter to trap these and convert them to an Enum of DataTypes, but why would the property grid fail when I select from the drop-down instead of double clicking or 'mouseewheeling' on the drop down?</p>