diff --git a/src/Main/Base/Project/Src/Gui/WorkbenchSingleton.cs b/src/Main/Base/Project/Src/Gui/WorkbenchSingleton.cs
index 82470dbb9f0..93f245457bc 100644
--- a/src/Main/Base/Project/Src/Gui/WorkbenchSingleton.cs
+++ b/src/Main/Base/Project/Src/Gui/WorkbenchSingleton.cs
@@ -57,7 +57,7 @@ public static class WorkbenchSingleton
 			}
 		}
 		
-		public static IStatusBarService StatusBar { 
+		public static IStatusBarService StatusBar {
 			get {
 				return workbench != null ? workbench.StatusBar : null;
 			}
@@ -77,10 +77,12 @@ public static void InitializeWorkbench(IWorkbench workbench, IWorkbenchLayout la
 			Project.CustomToolsService.Initialize();
 			Project.BuildModifiedProjectsOnlyService.Initialize();
 			
-			var messageService = (WinFormsMessageService)Core.Services.ServiceManager.Instance.MessageService;
-			messageService.DialogOwner = workbench.MainWin32Window;
-			Debug.Assert(messageService.DialogOwner != null);
-			messageService.DialogSynchronizeInvoke = workbench.SynchronizingObject;
+			var messageService = Core.Services.ServiceManager.Instance.MessageService as IDialogMessageService;
+			if (messageService != null) {
+				messageService.DialogOwner = workbench.MainWin32Window;
+				Debug.Assert(messageService.DialogOwner != null);
+				messageService.DialogSynchronizeInvoke = workbench.SynchronizingObject;
+			}
 			
 			workbench.Initialize();
 			workbench.SetMemento(PropertyService.Get(workbenchMemento, new Properties()));
diff --git a/src/Main/ICSharpCode.Core.WinForms/ICSharpCode.Core.WinForms.csproj b/src/Main/ICSharpCode.Core.WinForms/ICSharpCode.Core.WinForms.csproj
index 11cbbce1a9c..bc4adb189bf 100644
--- a/src/Main/ICSharpCode.Core.WinForms/ICSharpCode.Core.WinForms.csproj
+++ b/src/Main/ICSharpCode.Core.WinForms/ICSharpCode.Core.WinForms.csproj
@@ -59,6 +59,7 @@
     <Compile Include="Menu\MenuSeparator.cs" />
     <Compile Include="Menu\MenuService.cs" />
     <Compile Include="MessageService\CustomDialog.cs" />
+    <Compile Include="MessageService\IDialogMessageService.cs" />
     <Compile Include="MessageService\InputBox.cs" />
     <Compile Include="MessageService\SaveErrorChooseDialog.cs" />
     <Compile Include="MessageService\SaveErrorInformDialog.cs" />
diff --git a/src/Main/ICSharpCode.Core.WinForms/MessageService/IDialogMessageService.cs b/src/Main/ICSharpCode.Core.WinForms/MessageService/IDialogMessageService.cs
new file mode 100644
index 00000000000..83d83085787
--- /dev/null
+++ b/src/Main/ICSharpCode.Core.WinForms/MessageService/IDialogMessageService.cs
@@ -0,0 +1,24 @@
+// <file>
+//     <copyright see="prj:///doc/copyright.txt"/>
+//     <license see="prj:///doc/license.txt"/>
+//     <author name="Daniel Grunwald"/>
+//     <version>$Revision$</version>
+// </file>
+
+using System;
+using System.ComponentModel;
+using System.Windows.Forms;
+
+using ICSharpCode.Core.Services;
+
+namespace ICSharpCode.Core.WinForms
+{
+	/// <summary>
+	/// Message service that sets an owner for dialog boxes.
+	/// </summary>
+	public interface IDialogMessageService : IMessageService
+	{
+		IWin32Window DialogOwner { set; get; }
+		ISynchronizeInvoke DialogSynchronizeInvoke { set; get; }
+	}
+}
diff --git a/src/Main/ICSharpCode.Core.WinForms/MessageService/WinFormsMessageService.cs b/src/Main/ICSharpCode.Core.WinForms/MessageService/WinFormsMessageService.cs
index 888b0030f02..6809f7a0e77 100644
--- a/src/Main/ICSharpCode.Core.WinForms/MessageService/WinFormsMessageService.cs
+++ b/src/Main/ICSharpCode.Core.WinForms/MessageService/WinFormsMessageService.cs
@@ -18,7 +18,7 @@ namespace ICSharpCode.Core.WinForms
 	/// All text displayed using the MessageService is passed to the
 	/// <see cref="StringParser"/> to replace ${res} markers.
 	/// </summary>
-	public class WinFormsMessageService : IMessageService
+	public class WinFormsMessageService : IDialogMessageService
 	{
 		/// <summary>
 		/// Gets/Sets the form used as owner for shown message boxes.