Add interface to allow replacing WinFormsMessageService with a custom implementation when hosting SharpDevelop.

src/Main/Base/Project/Src/Gui/WorkbenchSingleton.cs

@@ -77,10 +77,12 @@ namespace ICSharpCode.SharpDevelop.Gui
 			Project.CustomToolsService.Initialize();
 			Project.BuildModifiedProjectsOnlyService.Initialize();
 			
-			var messageService = (WinFormsMessageService)Core.Services.ServiceManager.Instance.MessageService;
+			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()));

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" />

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; }
+	}
+}

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.