diff --git a/src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/CodeCompletion/BooResolver.cs b/src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/CodeCompletion/BooResolver.cs
index 08ef055673..d38209faa0 100644
--- a/src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/CodeCompletion/BooResolver.cs
+++ b/src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/CodeCompletion/BooResolver.cs
@@ -347,12 +347,51 @@ namespace Grunwald.BooBinding.CodeCompletion
 		void AddImportedNamespaceContents(ArrayList list)
 		{
 			IClass c;
-			foreach (KeyValuePair<string, string> pair in BooAmbience.TypeConversionTable) {
-				c = GetPrimitiveClass(pc, pair.Key, pair.Value);
+			foreach (KeyValuePair<string, string> pair in BooAmbience.ReverseTypeConversionTable) {
+				c = GetPrimitiveClass(pc, pair.Value, pair.Key);
 				if (c != null) list.Add(c);
 			}
+			list.Add(new DuckClass(cu));
 			NRResolver.AddImportedNamespaceContents(list, cu, callingClass);
 		}
+		
+		internal class DuckClass : DefaultClass
+		{
+			public DuckClass(ICompilationUnit cu) : base(cu, "duck")
+			{
+				Documentation = "Use late-binding to access members of this type.<br/>\n'If it walks like a duck and quacks like a duck, it must be a duck.'";
+				Modifiers = ModifierEnum.Public;
+			}
+			
+			protected override IReturnType CreateDefaultReturnType()
+			{
+				return new DuckReturnType(this);
+			}
+		}
+		
+		internal class DuckReturnType : AbstractReturnType
+		{
+			IClass c;
+			public DuckReturnType(IClass c) {
+				this.c = c;
+				FullyQualifiedName = c.FullyQualifiedName;
+			}
+			public override IClass GetUnderlyingClass() {
+				return c;
+			}
+			public override List<IMethod> GetMethods() {
+				return new List<IMethod>();
+			}
+			public override List<IProperty> GetProperties() {
+				return new List<IProperty>();
+			}
+			public override List<IField> GetFields() {
+				return new List<IField>();
+			}
+			public override List<IEvent> GetEvents() {
+				return new List<IEvent>();
+			}
+		}
 		#endregion
 	}
 }
diff --git a/src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/CodeCompletion/ConvertVisitor.cs b/src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/CodeCompletion/ConvertVisitor.cs
index d0e5c8c642..ad3a306a49 100644
--- a/src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/CodeCompletion/ConvertVisitor.cs
+++ b/src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/CodeCompletion/ConvertVisitor.cs
@@ -217,9 +217,13 @@ namespace Grunwald.BooBinding.CodeCompletion
 		                                           IMethodOrProperty callingMember, int caretLine, int caretColumn,
 		                                           IProjectContent projectContent)
 		{
+			System.Diagnostics.Debug.Assert(projectContent != null);
 			if (reference == null) {
-				LoggingService.Warn("inferred return type!");
-				return ReflectionReturnType.Object;
+				BooProject project = projectContent.Project as BooProject;
+				if (project != null && project.Ducky)
+					return new BooResolver.DuckClass(new DefaultCompilationUnit(projectContent)).DefaultReturnType;
+				else
+					return ReflectionReturnType.Object;
 			}
 			if (reference is AST.ArrayTypeReference) {
 				AST.ArrayTypeReference arr = (AST.ArrayTypeReference)reference;
@@ -230,7 +234,9 @@ namespace Grunwald.BooBinding.CodeCompletion
 				string name = ((AST.SimpleTypeReference)reference).Name;
 				IReturnType rt;
 				int typeParameterCount = (reference is AST.GenericTypeReference) ? ((AST.GenericTypeReference)reference).GenericArguments.Count : 0;
-				if (BooAmbience.ReverseTypeConversionTable.ContainsKey(name))
+				if (name == "duck")
+					rt = new BooResolver.DuckClass(new DefaultCompilationUnit(projectContent)).DefaultReturnType;
+				else if (BooAmbience.ReverseTypeConversionTable.ContainsKey(name))
 					rt = new GetClassReturnType(projectContent, BooAmbience.ReverseTypeConversionTable[name], typeParameterCount);
 				else
 					rt = new SearchClassReturnType(projectContent, callingClass, caretLine, caretColumn,
diff --git a/src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/CodeCompletion/InferredReturnType.cs b/src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/CodeCompletion/InferredReturnType.cs
index c262c98871..a7a70a2298 100644
--- a/src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/CodeCompletion/InferredReturnType.cs
+++ b/src/AddIns/BackendBindings/Boo/BooBinding/Project/Src/CodeCompletion/InferredReturnType.cs
@@ -102,6 +102,11 @@ namespace Grunwald.BooBinding.CodeCompletion
 				result = new ConstructedReturnType(enumerable.DefaultReturnType, new IReturnType[] { new InferredReturnType(node.Expression, context) });
 			}
 			
+			public override void OnCallableBlockExpression(CallableBlockExpression node)
+			{
+				// ignore return statements in callable blocks
+			}
+			
 			public override bool Visit(Node node)
 			{
 				if (result != null && !(result is NullReturnType))
diff --git a/src/Libraries/ICSharpCode.TextEditor/Project/Resources/Boo.xshd b/src/Libraries/ICSharpCode.TextEditor/Project/Resources/Boo.xshd
index 2e093d2cf0..ee793c29ba 100644
--- a/src/Libraries/ICSharpCode.TextEditor/Project/Resources/Boo.xshd
+++ b/src/Libraries/ICSharpCode.TextEditor/Project/Resources/Boo.xshd
@@ -173,6 +173,7 @@
 
 			<KeyWords name="ReferenceTypes" bold="true" italic="false" color="Purple" >
 				<Key word="object"/>
+				<Key word="duck"/>
 				<Key word="string"/>
 				<Key word="regex"/>
 			</KeyWords>
diff --git a/src/Main/Base/Project/Src/Dom/ReflectionLayer/ReflectionReturnType.cs b/src/Main/Base/Project/Src/Dom/ReflectionLayer/ReflectionReturnType.cs
index 1d366bb7c5..652c97c91e 100644
--- a/src/Main/Base/Project/Src/Dom/ReflectionLayer/ReflectionReturnType.cs
+++ b/src/Main/Base/Project/Src/Dom/ReflectionLayer/ReflectionReturnType.cs
@@ -116,16 +116,16 @@ namespace ICSharpCode.SharpDevelop.Dom
 				return ProjectContentRegistry.Mscorlib.GetClass(FullyQualifiedName);
 			}
 			public override List<IMethod> GetMethods() {
-				return new List<IMethod>(1);
+				return new List<IMethod>();
 			}
 			public override List<IProperty> GetProperties() {
-				return new List<IProperty>(1);
+				return new List<IProperty>();
 			}
 			public override List<IField> GetFields() {
-				return new List<IField>(1);
+				return new List<IField>();
 			}
 			public override List<IEvent> GetEvents() {
-				return new List<IEvent>(1);
+				return new List<IEvent>();
 			}
 		}
 		
diff --git a/src/Main/Base/Project/Src/Services/RefactoringService/RefactoringService.cs b/src/Main/Base/Project/Src/Services/RefactoringService/RefactoringService.cs
index 1d452610e0..9392dc5e26 100644
--- a/src/Main/Base/Project/Src/Services/RefactoringService/RefactoringService.cs
+++ b/src/Main/Base/Project/Src/Services/RefactoringService/RefactoringService.cs
@@ -37,19 +37,7 @@ namespace ICSharpCode.SharpDevelop.Refactoring
 					// can derive from the class
 					continue;
 				}
-				foreach (IClass c in pc.Classes) {
-					int count = c.BaseTypes.Count;
-					for (int i = 0; i < count; i++) {
-						string baseTypeName = c.BaseTypes[i].Name;
-						if (pc.Language.NameComparer.Equals(baseTypeName, baseClassName) ||
-						    pc.Language.NameComparer.Equals(baseTypeName, baseClassFullName)) {
-							IReturnType possibleBaseClass = c.GetBaseType(i);
-							if (possibleBaseClass.FullyQualifiedName == baseClass.FullyQualifiedName) {
-								list.Add(c);
-							}
-						}
-					}
-				}
+				AddDerivedClasses(pc, baseClass, baseClassName, baseClassFullName, pc.Classes, list);
 			}
 			if (!directDerivationOnly) {
 				List<IClass> additional = new List<IClass>();
@@ -63,6 +51,25 @@ namespace ICSharpCode.SharpDevelop.Refactoring
 			}
 			return list;
 		}
+		
+		static void AddDerivedClasses(IProjectContent pc, IClass baseClass, string baseClassName, string baseClassFullName,
+		                              IEnumerable<IClass> classList, IList<IClass> resultList)
+		{
+			foreach (IClass c in classList) {
+				AddDerivedClasses(pc, baseClass, baseClassName, baseClassFullName, c.InnerClasses, resultList);
+				int count = c.BaseTypes.Count;
+				for (int i = 0; i < count; i++) {
+					string baseTypeName = c.BaseTypes[i].Name;
+					if (pc.Language.NameComparer.Equals(baseTypeName, baseClassName) ||
+					    pc.Language.NameComparer.Equals(baseTypeName, baseClassFullName)) {
+						IReturnType possibleBaseClass = c.GetBaseType(i);
+						if (possibleBaseClass.FullyQualifiedName == baseClass.FullyQualifiedName) {
+							resultList.Add(c);
+						}
+					}
+				}
+			}
+		}
 		#endregion
 		
 		#region FindReferences