diff --git a/ICSharpCode.NRefactory.CSharp/Refactoring/Script.cs b/ICSharpCode.NRefactory.CSharp/Refactoring/Script.cs
index be486dc7e3..47f0350ae1 100644
--- a/ICSharpCode.NRefactory.CSharp/Refactoring/Script.cs
+++ b/ICSharpCode.NRefactory.CSharp/Refactoring/Script.cs
@@ -166,7 +166,11 @@ namespace ICSharpCode.NRefactory.CSharp.Refactoring
 		{
 			// Default implementation: do nothing
 			// Derived classes are supposed to enter the text editor's linked state.
-			return null;
+			
+			// Immediately signal the task as completed:
+			var tcs = new TaskCompletionSource<object>();
+			tcs.SetResult(null);
+			return tcs.Task;
 		}
 		
 		public void Replace (AstNode node, AstNode replaceWith)
diff --git a/ICSharpCode.NRefactory.CSharp/TypeSystem/CSharpAssembly.cs b/ICSharpCode.NRefactory.CSharp/TypeSystem/CSharpAssembly.cs
index 28ee59a3f0..fe72e9b576 100644
--- a/ICSharpCode.NRefactory.CSharp/TypeSystem/CSharpAssembly.cs
+++ b/ICSharpCode.NRefactory.CSharp/TypeSystem/CSharpAssembly.cs
@@ -290,6 +290,10 @@ namespace ICSharpCode.NRefactory.CSharp.TypeSystem
 				get { return assembly.Compilation; }
 			}
 			
+			IEnumerable<IAssembly> INamespace.ContributingAssemblies {
+				get { return new [] { assembly }; }
+			}
+			
 			INamespace INamespace.GetChildNamespace(string name)
 			{
 				var nameComparer = assembly.compilation.NameComparer;
diff --git a/ICSharpCode.NRefactory.CSharp/TypeSystem/ResolvedUsingScope.cs b/ICSharpCode.NRefactory.CSharp/TypeSystem/ResolvedUsingScope.cs
index f98d5a96ec..063a095192 100644
--- a/ICSharpCode.NRefactory.CSharp/TypeSystem/ResolvedUsingScope.cs
+++ b/ICSharpCode.NRefactory.CSharp/TypeSystem/ResolvedUsingScope.cs
@@ -172,6 +172,10 @@ namespace ICSharpCode.NRefactory.CSharp.TypeSystem
 				get { return EmptyList<ITypeDefinition>.Instance; }
 			}
 			
+			IEnumerable<IAssembly> INamespace.ContributingAssemblies {
+				get { return EmptyList<IAssembly>.Instance; }
+			}
+			
 			ICompilation IResolved.Compilation {
 				get { return parentNamespace.Compilation; }
 			}
diff --git a/ICSharpCode.NRefactory/TypeSystem/INamespace.cs b/ICSharpCode.NRefactory/TypeSystem/INamespace.cs
index 487e4fc3e3..b3631fe060 100644
--- a/ICSharpCode.NRefactory/TypeSystem/INamespace.cs
+++ b/ICSharpCode.NRefactory/TypeSystem/INamespace.cs
@@ -62,6 +62,11 @@ namespace ICSharpCode.NRefactory.TypeSystem
 		/// </summary>
 		IEnumerable<ITypeDefinition> Types { get; }
 		
+		/// <summary>
+		/// Gets the assemblies that contribute types to this namespace (or to child namespaces).
+		/// </summary>
+		IEnumerable<IAssembly> ContributingAssemblies { get; }
+		
 		/// <summary>
 		/// Gets a direct child namespace by its short name.
 		/// Returns null when the namespace cannot be found.
diff --git a/ICSharpCode.NRefactory/TypeSystem/Implementation/DefaultUnresolvedAssembly.cs b/ICSharpCode.NRefactory/TypeSystem/Implementation/DefaultUnresolvedAssembly.cs
index b3aba10d88..d74c1cae84 100644
--- a/ICSharpCode.NRefactory/TypeSystem/Implementation/DefaultUnresolvedAssembly.cs
+++ b/ICSharpCode.NRefactory/TypeSystem/Implementation/DefaultUnresolvedAssembly.cs
@@ -378,6 +378,10 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 					get { return parentNamespace; }
 				}
 				
+				IEnumerable<IAssembly> INamespace.ContributingAssemblies {
+					get { return new [] { assembly }; }
+				}
+				
 				IEnumerable<INamespace> INamespace.ChildNamespaces {
 					get { return childNamespaces; }
 				}
diff --git a/ICSharpCode.NRefactory/TypeSystem/Implementation/MergedNamespace.cs b/ICSharpCode.NRefactory/TypeSystem/Implementation/MergedNamespace.cs
index 4363253f05..1ab85bcd4e 100644
--- a/ICSharpCode.NRefactory/TypeSystem/Implementation/MergedNamespace.cs
+++ b/ICSharpCode.NRefactory/TypeSystem/Implementation/MergedNamespace.cs
@@ -20,7 +20,6 @@ using System;
 using System.Collections.Generic;
 using System.Globalization;
 using System.Linq;
-using System.Text;
 using ICSharpCode.NRefactory.Utils;
 
 namespace ICSharpCode.NRefactory.TypeSystem.Implementation
@@ -96,6 +95,10 @@ namespace ICSharpCode.NRefactory.TypeSystem.Implementation
 			get { return compilation; }
 		}
 		
+		public IEnumerable<IAssembly> ContributingAssemblies {
+			get { return namespaces.SelectMany(ns => ns.ContributingAssemblies); }
+		}
+		
 		public IEnumerable<INamespace> ChildNamespaces {
 			get { return GetChildNamespaces().Values; }
 		}