IDictionary (and not just ResourceDictionary) is considered a collection and supported by own XamlParser.

src/AddIns/DisplayBindings/WpfDesign/WpfDesign.Designer/Tests/XamlDom/ExampleClassContainer.cs

@@ -11,6 +11,10 @@ namespace ICSharpCode.WpfDesign.Tests.XamlDom
 	{
 	}
 	
+	public class ExampleClassDictionary : Dictionary<string, ExampleClass>
+	{
+	}
+	
 	[ContentProperty("List")]
 	public class ExampleClassContainer : ExampleClass
 	{
@@ -35,5 +39,18 @@ namespace ICSharpCode.WpfDesign.Tests.XamlDom
 				otherList = value;
 			}
 		}
+		
+		ExampleClassDictionary dictionary = new ExampleClassDictionary();
+		
+		public ExampleClassDictionary Dictionary {
+			get {
+				TestHelperLog.Log("Dictionary.get " + Identity);
+				return dictionary;
+			}
+			set {
+				TestHelperLog.Log("Dictionary.set " + Identity);
+				dictionary = value;
+			}
+		}
 	}
 }

src/AddIns/DisplayBindings/WpfDesign/WpfDesign.Designer/Tests/XamlDom/SimpleLoadTests.cs

@@ -208,6 +208,88 @@ namespace ICSharpCode.WpfDesign.Tests.XamlDom
 			");
 		}
 		
+		[Test]
+		public void ContainerImplicitDictionary()
+		{
+			TestLoading(@"
+<ExampleClassContainer
+  xmlns=""" + XamlTypeFinderTests.XamlDomTestsNamespace + @"""
+  xmlns:x=""http://schemas.microsoft.com/winfx/2006/xaml"">
+   <ExampleClassContainer.Dictionary>
+     <ExampleClass x:Key=""key1"" OtherProp=""a""> </ExampleClass>
+     <ExampleClass x:Key=""key2"" OtherProp=""b"" />
+     <ExampleClass x:Key=""key3"" OtherProp=""c"" />
+   </ExampleClassContainer.Dictionary>
+</ExampleClassContainer>
+			");
+		}
+		
+		[Test]
+		public void ContainerExplicitDictionary()
+		{
+			TestLoading(@"
+<ExampleClassContainer
+  xmlns=""" + XamlTypeFinderTests.XamlDomTestsNamespace + @"""
+  xmlns:x=""http://schemas.microsoft.com/winfx/2006/xaml"">
+   <ExampleClassContainer.Dictionary>
+      <ExampleClassDictionary>
+         <ExampleClass x:Key=""key1"" OtherProp=""a""> </ExampleClass>
+         <ExampleClass x:Key=""key2"" OtherProp=""b"" />
+         <ExampleClass x:Key=""key3"" OtherProp=""c"" />
+      </ExampleClassDictionary>
+   </ExampleClassContainer.Dictionary>
+</ExampleClassContainer>
+			");
+		}
+		
+		[Test]
+		public void ResourceDictionaryImplicit()
+		{
+			TestLoading(@"
+<Window
+  xmlns=""http://schemas.microsoft.com/netfx/2007/xaml/presentation""
+  xmlns:t=""" + XamlTypeFinderTests.XamlDomTestsNamespace + @"""
+  xmlns:x=""http://schemas.microsoft.com/winfx/2006/xaml"">
+  <Window.Resources>
+     <t:ExampleClass x:Key=""key1"" OtherProp=""a""> </t:ExampleClass>
+     <t:ExampleClass x:Key=""key2"" OtherProp=""b"" />
+  </Window.Resources>
+</Window>
+			");
+		}
+		
+		[Test]
+		public void ResourceDictionaryExplicitWinfx2006()
+		{
+			ResourceDictionaryExplicitInternal("http://schemas.microsoft.com/winfx/2006/xaml/presentation");
+		}
+		
+		[Test]
+		[Ignore("Own XamlParser should handle different namespaces pointing to same types, because builtin XamlReader does.")]
+		public void ResourceDictionaryExplicitNetfx2007()
+		{
+			// The reason this test case fails is because own XamlParser cannot always handle the case where multiple xmlns points to the same type.
+			// In this test case the default xmlns is set to netfx/20007 (compare with the test above that uses winfx/2006 and is successfully executed).
+			ResourceDictionaryExplicitInternal("http://schemas.microsoft.com/netfx/2007/xaml/presentation");
+		}
+		
+		void ResourceDictionaryExplicitInternal(string defaultXmlns)
+		{
+			TestLoading(@"
+<Window
+  xmlns=""" + defaultXmlns + @"""
+  xmlns:t=""" + XamlTypeFinderTests.XamlDomTestsNamespace + @"""
+  xmlns:x=""http://schemas.microsoft.com/winfx/2006/xaml"">
+  <Window.Resources>
+     <ResourceDictionary>
+        <t:ExampleClass x:Key=""key1"" OtherProp=""a""> </t:ExampleClass>
+        <t:ExampleClass x:Key=""key2"" OtherProp=""b"" />
+     </ResourceDictionary>
+  </Window.Resources>
+</Window>
+			");
+		}
+		
 		[Test]
 		public void ExampleServiceTest()
 		{

src/AddIns/DisplayBindings/WpfDesign/WpfDesign.XamlDom/Project/CollectionSupport.cs

@@ -25,7 +25,7 @@ namespace ICSharpCode.WpfDesign.XamlDom
 			return typeof(IList).IsAssignableFrom(type)
 				|| type.IsArray
 				|| typeof(IAddChild).IsAssignableFrom(type)
-				|| typeof(ResourceDictionary).IsAssignableFrom(type);
+				|| typeof(IDictionary).IsAssignableFrom(type);
 		}		
 
 		/// <summary>
@@ -65,7 +65,7 @@ namespace ICSharpCode.WpfDesign.XamlDom
 				} else {
 					addChild.AddChild(newElement.GetValueFor(null));
 				}
-			} else if (collectionInstance is ResourceDictionary) {
+			} else if (collectionInstance is IDictionary) {
 				object val = newElement.GetValueFor(null);
 				object key = newElement is XamlObject ? ((XamlObject)newElement).GetXamlAttribute("Key") : null;
 				//if (key == null || key == "") {
@@ -74,7 +74,7 @@ namespace ICSharpCode.WpfDesign.XamlDom
 				//}
 				if (key == null || key == "")
 					key = val;
-				((ResourceDictionary)collectionInstance).Add(key, val);
+				((IDictionary)collectionInstance).Add(key, val);
 			} else {
 				collectionType.InvokeMember(
 					"Add", BindingFlags.Public | BindingFlags.InvokeMethod | BindingFlags.Instance,