PropertyGrid: Added new attribute called ItemsSourceAttribute which allows you to use an attribute to specify a custom items source for a ComboBox editor. To use simply create a custom class the implements the IItemsSource interface:

public class ColorSource : IItemsSource
    {
        public IList<object> GetValues()
        {
            return new List<object>() { Colors.Blue, Colors.Gray, Colors.Green };
        }
    }

Then decorate your property with the ItemsSource attirbute and specify the Type of source to use:

        private Color _color = Colors.Green;
        [ItemsSource(typeof(ColorSource))]
        public Color Color
        {
            get { return _color; }
            set { _color = value; }
        }

When the PropertyGrid loads, the editor for the Color property will be a ComboBox with an ItemsSource of ColorSource.GetValues().

ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/PropertyGrid/Implementation/Attributes/IItemsSource.cs

@@ -0,0 +1,10 @@
+using System;
+using System.Collections.Generic;
+
+namespace Microsoft.Windows.Controls.PropertyGrid.Attributes
+{
+    public interface IItemsSource
+    {
+        IList<object> GetValues();
+    }
+}

ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/PropertyGrid/Implementation/Attributes/ItemsSourceAttribute.cs

@@ -0,0 +1,18 @@
+using System;
+
+namespace Microsoft.Windows.Controls.PropertyGrid.Attributes
+{
+    public class ItemsSourceAttribute : Attribute
+    {
+        public Type Type { get; set; }
+
+        public ItemsSourceAttribute(Type type)
+        {
+            var valueSourceInterface = type.GetInterface("Microsoft.Windows.Controls.PropertyGrid.Attributes.IItemsSource");
+            if (valueSourceInterface == null)
+                throw new ArgumentException("Type must implement the IItemsSource interface.", "type");
+
+            Type = type;
+        }
+    }
+}

ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/PropertyGrid/Implementation/Editors/ItemsSourceEditor.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using Microsoft.Windows.Controls.PropertyGrid.Attributes;
+
+namespace Microsoft.Windows.Controls.PropertyGrid.Editors
+{
+    public class ItemsSourceEditor : ComboBoxEditor
+    {
+        private ItemsSourceAttribute _attribute;
+
+        public ItemsSourceEditor(ItemsSourceAttribute attribute)
+        {
+            _attribute = attribute;
+        }
+
+        protected override IList<object> CreateItemsSource(PropertyItem propertyItem)
+        {
+            var instance = Activator.CreateInstance(_attribute.Type);
+            return (instance as IItemsSource).GetValues();
+        }
+    }
+}

ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/PropertyGrid/Implementation/PropertyGrid.cs

@@ -10,6 +10,7 @@ using System.ComponentModel;
 using System.Windows.Input;
 using Microsoft.Windows.Controls.PropertyGrid.Editors;
 using Microsoft.Windows.Controls.PropertyGrid.Commands;
+using Microsoft.Windows.Controls.PropertyGrid.Attributes;
 
 namespace Microsoft.Windows.Controls.PropertyGrid
 {
@@ -413,15 +414,42 @@ namespace Microsoft.Windows.Controls.PropertyGrid
 
         private FrameworkElement GetTypeEditor(PropertyItem propertyItem)
         {
-            FrameworkElement editor = GetCustomEditor(propertyItem, EditorDefinitions);
+            //first check for any attribute editor
+            FrameworkElement editor = GetAttibuteEditor(propertyItem);
 
+            //now look for a custom editor based on editor definitions
+            if (editor == null)
+                editor = GetCustomEditor(propertyItem, EditorDefinitions);
+
+            //guess we have to use the default editor
             if (editor == null)
                 editor = CreateDefaultEditor(propertyItem);
 
             return editor;
         }
 
-        private FrameworkElement GetCustomEditor(PropertyItem propertyItem, EditorDefinitionCollection customTypeEditors)
+        private static FrameworkElement GetAttibuteEditor(PropertyItem propertyItem)
+        {
+            FrameworkElement editor = null;
+
+            var attribute = GetAttribute<ItemsSourceAttribute>(propertyItem.PropertyDescriptor);
+            if (attribute != null)
+                editor = new ItemsSourceEditor(attribute).ResolveEditor(propertyItem);
+
+            return editor;
+        }
+
+        public static T GetAttribute<T>(PropertyDescriptor property) where T : Attribute
+        {
+            foreach (Attribute att in property.Attributes)
+            {
+                var tAtt = att as T;
+                if (tAtt != null) return tAtt;
+            }
+            return null;
+        }
+
+        private static FrameworkElement GetCustomEditor(PropertyItem propertyItem, EditorDefinitionCollection customTypeEditors)
         {
             FrameworkElement editor = null;
 
@@ -446,7 +474,7 @@ namespace Microsoft.Windows.Controls.PropertyGrid
             return editor;
         }
 
-        private FrameworkElement CreateDefaultEditor(PropertyItem propertyItem)
+        private static FrameworkElement CreateDefaultEditor(PropertyItem propertyItem)
         {
             ITypeEditor editor = null;
 

ExtendedWPFToolkitSolution/Src/WPFToolkit.Extended/WPFToolkit.Extended.csproj

@@ -237,6 +237,8 @@
       <DesignTimeSharedInput>True</DesignTimeSharedInput>
     </Compile>
     <Compile Include="BusyIndicator\Implementation\VisualStates.BusyIndicator.cs" />
+    <Compile Include="PropertyGrid\Implementation\Attributes\IItemsSource.cs" />
+    <Compile Include="PropertyGrid\Implementation\Attributes\ItemsSourceAttribute.cs" />
     <Compile Include="PropertyGrid\Implementation\Commands\PropertyGridCommands.cs" />
     <Compile Include="PropertyGrid\Implementation\Converters\ValueSourceToImagePathConverter.cs" />
     <Compile Include="PropertyGrid\Implementation\Converters\ValueSourceToToolTipConverter.cs" />
@@ -256,6 +258,7 @@
     <Compile Include="PropertyGrid\Implementation\Editors\DoubleUpDownEditor.cs" />
     <Compile Include="PropertyGrid\Implementation\Editors\EnumComboBoxEditor.cs" />
     <Compile Include="PropertyGrid\Implementation\Editors\FontComboBoxEditor.cs" />
+    <Compile Include="PropertyGrid\Implementation\Editors\ItemsSourceEditor.cs" />
     <Compile Include="PropertyGrid\Implementation\Editors\TimeSpanEditor.cs" />
     <Compile Include="PropertyGrid\Implementation\IEditorDefinition.cs" />
     <Compile Include="PropertyGrid\Implementation\Editors\IntegerUpDownEditor.cs" />