Attempt to port AvalonEditViewContent to new OpenedFile model.

Problem: document services now may be shared across multiple views; which is problematic as some code expects ITextMarkerService to be per-view.
Also, editor extensions might not support switching to a different IDocument instance - we should probably Detach + re-Attach extensions to avoid problems.

src/AddIns/BackendBindings/WixBinding/Project/Src/WixDocumentReader.cs

@@ -63,6 +63,7 @@ namespace ICSharpCode.WixBinding
 		public WixDocumentReader(TextReader textReader)
 		{
 			reader = new XmlTextReader(textReader);
+			reader.XmlResolver = null;
 		}
 		
 		public ReadOnlyCollection<string> GetDialogIds()

src/AddIns/DisplayBindings/AvalonEdit.AddIn/Src/AvalonEditDisplayBinding.cs

@@ -17,13 +17,16 @@
 // DEALINGS IN THE SOFTWARE.
 
 using System;
+using System.ComponentModel.Design;
 using System.IO;
 using System.Linq;
 using System.Text;
 
+using ICSharpCode.AvalonEdit.Document;
 using ICSharpCode.AvalonEdit.Highlighting;
 using ICSharpCode.AvalonEdit.Utils;
 using ICSharpCode.Core;
+using ICSharpCode.NRefactory.Editor;
 using ICSharpCode.SharpDevelop;
 using ICSharpCode.SharpDevelop.Gui;
 using ICSharpCode.SharpDevelop.Project;
@@ -77,23 +80,49 @@ namespace ICSharpCode.AvalonEdit.AddIn
 			return true;
 		}
 		
-		public IViewContent CreateContentForFile(OpenedFile file)
+		static Encoding DetectExistingEncoding(OpenedFile file)
 		{
-			ChooseEncodingDialog dlg = new ChooseEncodingDialog();
+			var existingTextModel = file.GetModel(FileModels.TextDocument, GetModelOptions.DoNotLoad);
-			dlg.Owner = SD.Workbench.MainWindow;
+			if (existingTextModel != null)
-			using (Stream stream = file.OpenRead()) {
+				return existingTextModel.GetFileModelInfo().Encoding;
+			using (Stream stream = file.GetModel(FileModels.Binary).OpenRead()) {
 				using (StreamReader reader = FileReader.OpenStream(stream, SD.FileService.DefaultFileEncoding)) {
-					reader.Peek(); // force reader to auto-detect encoding
+					reader.Peek();
-					dlg.Encoding = reader.CurrentEncoding;
+					// force reader to auto-detect encoding
+					return reader.CurrentEncoding;
 				}
 			}
+		}
+		
+		public IViewContent CreateContentForFile(OpenedFile file)
+		{
+			ChooseEncodingDialog dlg = new ChooseEncodingDialog();
+			dlg.Owner = SD.Workbench.MainWindow;
+			dlg.Encoding = DetectExistingEncoding(file);
 			if (dlg.ShowDialog() == true) {
-				return new AvalonEditViewContent(file, dlg.Encoding);
+				LoadWithEncoding(file, dlg.Encoding);
+				return new AvalonEditViewContent(file);
 			} else {
 				return null;
 			}
 		}
 		
+		static void LoadWithEncoding(OpenedFile file, Encoding encoding)
+		{
+			var doc = file.GetModel(FileModels.TextDocument, GetModelOptions.DoNotLoad | GetModelOptions.AllowStale);
+			if (doc == null)
+				doc = new TextDocument();
+			doc.GetFileModelInfo().Encoding = encoding;
+			string newText;
+			using (Stream stream = file.GetModel(FileModels.Binary).OpenRead()) {
+				using (StreamReader reader = new StreamReader(stream, encoding, detectEncodingFromByteOrderMarks: false)) {
+					newText = reader.ReadToEnd();
+				}
+			}
+			FileModels.TextDocument.ReloadDocument(doc, new StringTextSource(newText));
+			file.ReplaceModel(FileModels.TextDocument, doc, ReplaceModelMode.SetAsValid);
+		}
+		
 		public bool IsPreferredBindingForFile(FileName fileName)
 		{
 			return false;
@@ -105,3 +134,4 @@ namespace ICSharpCode.AvalonEdit.AddIn
 		}
 	}
 }
+						

src/AddIns/DisplayBindings/AvalonEdit.AddIn/Src/AvalonEditViewContent.cs

@@ -45,17 +45,13 @@ namespace ICSharpCode.AvalonEdit.AddIn
 		readonly CodeEditor codeEditor = new CodeEditor();
 		IAnalyticsMonitorTrackedFeature trackedFeature;
 		
-		public AvalonEditViewContent(OpenedFile file, Encoding fixedEncodingForLoading = null)
+		public AvalonEditViewContent(OpenedFile file)
 		{
 			// Use common service container for view content and primary text editor.
 			// This makes all text editor services available as view content services and vice versa.
 			// (with the exception of the interfaces implemented directly by this class,
 			// those are available as view-content services only)
 			this.Services = codeEditor.PrimaryTextEditor.GetRequiredService<IServiceContainer>();
-			if (fixedEncodingForLoading != null) {
-				codeEditor.UseFixedEncoding = true;
-				codeEditor.PrimaryTextEditor.Encoding = fixedEncodingForLoading;
-			}
 			this.TabPageText = "${res:FormsDesigner.DesignTabPages.SourceTabPage}";
 			
 			if (file.FileName != null) {
@@ -66,10 +62,7 @@ namespace ICSharpCode.AvalonEdit.AddIn
 			}
 			
 			this.Files.Add(file);
-			file.ForceInitializeView(this);
+			this.LoadModel();
-			
-			file.IsDirtyChanged += PrimaryFile_IsDirtyChanged;
-			codeEditor.Document.UndoStack.PropertyChanged += codeEditor_Document_UndoStack_PropertyChanged;
 		}
 		
 		bool IsKnownFileExtension(string filetype)
@@ -86,30 +79,19 @@ namespace ICSharpCode.AvalonEdit.AddIn
 			get { return codeEditor.PrimaryTextEditor.TextArea; }
 		}
 		
-		bool isLoading;
 		
-		public override void Load(OpenedFile file, Stream stream)
+		public override void LoadModel()
 		{
-			if (file != PrimaryFile)
+			// if (!file.IsUntitled) {
-				return;
+			//    codeEditor.PrimaryTextEditor.IsReadOnly = (File.GetAttributes(file.FileName) & FileAttributes.ReadOnly) == FileAttributes.ReadOnly;
-			isLoading = true;
+			// }
-			try {
-				if (!file.IsUntitled) {
-					codeEditor.PrimaryTextEditor.IsReadOnly = (File.GetAttributes(file.FileName) & FileAttributes.ReadOnly) == FileAttributes.ReadOnly;
-				}
 			
-				codeEditor.Load(stream);
+			codeEditor.Document = PrimaryFile.GetModel(FileModels.TextDocument);
-				// Load() causes the undo stack to think stuff changed, so re-mark the file as original if necessary
+			base.LoadModel();
-				if (!this.PrimaryFile.IsDirty) {
-					codeEditor.Document.UndoStack.MarkAsOriginalFile();
-				}
 			
-				// we set the file name after loading because this will place the fold markers etc.
+			// we set the file name after loading because this will place the fold markers etc.
-				codeEditor.FileName = file.FileName;
+			codeEditor.FileName = PrimaryFile.FileName;
-				BookmarksAttach();
+			BookmarksAttach();
-			} finally {
-				isLoading = false;
-			}
 		}
 		
 		protected override void OnFileNameChanged(OpenedFile file)

src/AddIns/DisplayBindings/AvalonEdit.AddIn/Src/CodeEditor.cs

@@ -281,38 +281,6 @@ namespace ICSharpCode.AvalonEdit.AddIn
 			}
 		}
 		
-		// always use primary text editor for loading/saving
-		// (the file encoding is stored only there)
-		public void Load(Stream stream)
-		{
-			if (UseFixedEncoding) {
-				using (StreamReader reader = new StreamReader(stream, primaryTextEditor.Encoding, detectEncodingFromByteOrderMarks: false)) {
-					ReloadDocument(primaryTextEditor.Document, reader.ReadToEnd());
-				}
-			} else {
-				// do encoding auto-detection
-				using (StreamReader reader = FileReader.OpenStream(stream, this.Encoding ?? SD.FileService.DefaultFileEncoding)) {
-					ReloadDocument(primaryTextEditor.Document, reader.ReadToEnd());
-					this.Encoding = reader.CurrentEncoding;
-				}
-			}
-			// raise event which allows removing existing NewLineConsistencyCheck overlays
-			if (LoadedFileContent != null)
-				LoadedFileContent(this, EventArgs.Empty);
-			NewLineConsistencyCheck.StartConsistencyCheck(this);
-		}
-		
-		public event EventHandler LoadedFileContent;
-		
-		public void Save(Stream stream)
-		{
-			// don't use TextEditor.Save here because that would touch the Modified flag,
-			// but OpenedFile is already managing IsDirty
-			using (StreamWriter writer = new StreamWriter(stream, primaryTextEditor.Encoding ?? Encoding.UTF8)) {
-				primaryTextEditor.Document.WriteTextTo(writer);
-			}
-		}
-		
 		public event EventHandler CaretPositionChanged;
 		
 		void TextAreaCaretPositionChanged(object sender, EventArgs e)
@@ -336,7 +304,6 @@ namespace ICSharpCode.AvalonEdit.AddIn
 			}
 			
 			NavigationService.Log(this.BuildNavPoint());
-			var document = this.Document;
 			int lineOffset = document.GetLineByNumber(this.Line).Offset;
 			int chOffset = this.Column;
 			int col = 1;

src/AddIns/DisplayBindings/AvalonEdit.AddIn/Src/Commands/SaveFileWithEncoding.cs

@@ -18,6 +18,7 @@
 
 using System;
 using ICSharpCode.Core;
+using ICSharpCode.NRefactory.Editor;
 using ICSharpCode.SharpDevelop;
 using ICSharpCode.SharpDevelop.Gui;
 
@@ -37,9 +38,9 @@ namespace ICSharpCode.AvalonEdit.AddIn.Commands
 			if (codeEditor != null) {
 				ChooseEncodingDialog dlg = new ChooseEncodingDialog();
 				dlg.Owner = SD.Workbench.MainWindow;
-				dlg.Encoding = codeEditor.PrimaryTextEditor.Encoding;
+				dlg.Encoding = codeEditor.Document.GetFileModelInfo().Encoding;
 				if (dlg.ShowDialog() == true) {
-					codeEditor.PrimaryTextEditor.Encoding = dlg.Encoding;
+					codeEditor.Document.GetFileModelInfo().Encoding = dlg.Encoding;
 					SharpDevelop.Commands.SaveFile.Save(vc.PrimaryFile);
 				}
 			}

src/AddIns/DisplayBindings/AvalonEdit.AddIn/Src/NewLineConsistencyCheck.cs

@@ -125,16 +125,13 @@ namespace ICSharpCode.AvalonEdit.AddIn
 			
 			var featureUse = SD.AnalyticsMonitor.TrackFeature(typeof(NewLineConsistencyCheck));
 			
-			EventHandler removeWarning = null;
+			EventHandler removeWarning = delegate {
-			removeWarning = delegate {
 				groupBox.Remove();
 				editor.PrimaryTextEditor.TextArea.Focus();
-				editor.LoadedFileContent -= removeWarning;
 				
 				featureUse.EndTracking();
 			};
 			
-			editor.LoadedFileContent += removeWarning;
 			cancelButton.Click += delegate {
 				SD.AnalyticsMonitor.TrackFeature(typeof(NewLineConsistencyCheck), "cancelButton");
 				removeWarning(null, null);

src/AddIns/DisplayBindings/HexEditor/Project/Src/View/HexEditView.cs

@@ -138,9 +138,5 @@ namespace HexEditor.View
 		{
 			if (PrimaryFile != null) PrimaryFile.MakeDirty();
 		}
-		
-		public override bool IsDirty {
-			get { return base.IsDirty; }
-		}
 	}
 }

src/AddIns/DisplayBindings/WpfDesign/WpfDesign.AddIn/Src/WpfViewContent.cs

@@ -101,6 +101,7 @@ namespace ICSharpCode.WpfDesign.AddIn
 				outline.Root = null;
 			}
 			using (XmlTextReader r = new XmlTextReader(stream)) {
+				r.XmlResolver = null;
 				XamlLoadSettings settings = new XamlLoadSettings();
 				settings.DesignerAssemblies.Add(typeof(WpfViewContent).Assembly);
 				settings.CustomServiceRegisterFunctions.Add(

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

@@ -706,6 +706,7 @@ namespace ICSharpCode.WpfDesign.XamlDom
 		public static XamlObject ParseSnippet(XamlObject root, string xaml, XamlParserSettings settings)
 		{
 			XmlTextReader reader = new XmlTextReader(new StringReader(xaml));
+			reader.XmlResolver = null;
 			var element = root.OwnerDocument.XmlDocument.ReadNode(reader);
 			
 			if (element != null) {

src/AddIns/DisplayBindings/XmlEditor/Project/Src/XmlView.cs

@@ -230,7 +230,8 @@ namespace ICSharpCode.XmlEditor
 			TaskService.ClearExceptCommentTasks();
 			if (IsWellFormed) {
 				try {
-					using (XmlTextReader reader = new XmlTextReader(new StringReader(editor.Document.Text))) {
+					using (XmlTextReader reader = new XmlTextReader(editor.Document.CreateReader())) {
+						reader.XmlResolver = null;
 						XmlSchemaInference schemaInference = new XmlSchemaInference();
 						XmlSchemaSet schemaSet = schemaInference.InferSchema(reader);
 						return GetSchemas(schemaSet, editor);
@@ -351,8 +352,7 @@ namespace ICSharpCode.XmlEditor
 			if (editor == null) return false;
 			
 			try {
-				StringReader stringReader = new StringReader(editor.Document.Text);
+				XmlTextReader xmlReader = new XmlTextReader(editor.Document.CreateReader());
-				XmlTextReader xmlReader = new XmlTextReader(stringReader);
 				xmlReader.XmlResolver = null;
 				XmlReaderSettings settings = new XmlReaderSettings();
 				settings.ValidationType = ValidationType.Schema;
@@ -398,8 +398,7 @@ namespace ICSharpCode.XmlEditor
 			ITextEditor editor = TextEditor;
 			if (editor == null) return false;
 			
-			StringReader stringReader = new StringReader(editor.Document.Text);
+			XmlTextReader xmlReader = new XmlTextReader(editor.Document.CreateReader());
-			XmlTextReader xmlReader = new XmlTextReader(stringReader);
 			xmlReader.XmlResolver = null;
 
 			try	{

src/Main/Base/Project/Util/SharpDevelopExtensions.cs

@@ -19,6 +19,7 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
+using System.ComponentModel.Design;
 using System.IO;
 using System.Linq;
 using System.Text;
@@ -920,7 +921,7 @@ namespace ICSharpCode.SharpDevelop
 		/// Gets an <see cref="IImage"/> from a resource.
 		/// </summary>
 		/// <exception cref="ResourceNotFoundException">The resource with the specified name does not exist</exception>
-		public static IImage GetImage(this IResourceService resourceService, string resourceName)
+		public static IImage GetImage(this ICSharpCode.Core.IResourceService resourceService, string resourceName)
 		{
 			if (resourceService == null)
 				throw new ArgumentNullException("resourceService");
@@ -933,7 +934,7 @@ namespace ICSharpCode.SharpDevelop
 		/// Gets an image source from a resource.
 		/// </summary>
 		/// <exception cref="ResourceNotFoundException">The resource with the specified name does not exist</exception>
-		public static ImageSource GetImageSource(this IResourceService resourceService, string resourceName)
+		public static ImageSource GetImageSource(this ICSharpCode.Core.IResourceService resourceService, string resourceName)
 		{
 			if (resourceService == null)
 				throw new ArgumentNullException("resourceService");
@@ -1035,7 +1036,12 @@ namespace ICSharpCode.SharpDevelop
 		/// </summary>
 		public static DocumentFileModelInfo GetFileModelInfo(this TextDocument document)
 		{
-			return document.GetService<DocumentFileModelInfo>();
+			var info = document.GetService<DocumentFileModelInfo>();
+			if (info == null) {
+				info = new DocumentFileModelInfo();
+				document.GetRequiredService<IServiceContainer>().AddService(typeof(DocumentFileModelInfo), info);
+			}
+			return info;
 		}
 		
 		/// <summary>

src/Main/Base/Project/Workbench/AbstractViewContent.cs

@@ -89,6 +89,10 @@ namespace ICSharpCode.SharpDevelop.Workbench
 		{
 		}
 		
+		public virtual void LoadModel()
+		{
+		}
+		
 		string tabPageText = "TabPageText";
 		
 		public event EventHandler TabPageTextChanged;

src/Main/Base/Project/Workbench/File/BinaryFileModelProvider.cs

@@ -65,6 +65,10 @@ namespace ICSharpCode.SharpDevelop.Workbench
 		{
 		}
 		
+		public void NotifyLoaded(OpenedFile file, IBinaryFileModel model)
+		{
+		}
+		
 		public void NotifyUnloaded(OpenedFile file, IBinaryFileModel model)
 		{
 		}

src/Main/Base/Project/Workbench/File/DocumentFileModelInfo.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Text;
+using ICSharpCode.AvalonEdit.Document;
 
 namespace ICSharpCode.SharpDevelop.Workbench
 {
@@ -11,6 +12,9 @@ namespace ICSharpCode.SharpDevelop.Workbench
 	/// </summary>
 	public class DocumentFileModelInfo
 	{
+		OpenedFile file;
+		TextDocument document;
+		
 		public DocumentFileModelInfo()
 		{
 			this.Encoding = SD.FileService.DefaultFileEncoding;
@@ -30,5 +34,52 @@ namespace ICSharpCode.SharpDevelop.Workbench
 		/// Gets the encoding of the model.
 		/// </summary>
 		public Encoding Encoding { get; set; }
+		
+		internal void NotifyLoaded(OpenedFile file, TextDocument document)
+		{
+			if (this.file != null)
+				throw new InvalidOperationException("Duplicate NotifyLoaded() call");
+			this.file = file;
+			this.document = document;
+			document.TextChanged += OnDocumentTextChanged;
+			file.IsDirtyChanged += OnFileIsDirtyChanged;
+			UpdateUndoStackIsOriginalFile();
+		}
+		
+		internal void NotifyUnloaded()
+		{
+			document.TextChanged -= OnDocumentTextChanged;
+			file.IsDirtyChanged -= OnFileIsDirtyChanged;
+			this.IsStale = true;
+			this.file = null;
+			this.document = null;
+		}
+		
+		void OnDocumentTextChanged(object sender, EventArgs e)
+		{
+			if (!isLoading) {
+				// Set dirty flag on OpenedFile according to UndoStack.IsOriginalFile
+				if (document.UndoStack.IsOriginalFile && file.IsDirty) {
+					// reset dirty marker
+					file.ReplaceModel(FileModels.TextDocument, document, ReplaceModelMode.SetAsValid);
+				} else if (!document.UndoStack.IsOriginalFile) {
+					file.MakeDirty(FileModels.TextDocument);
+				}
+			}
+		}
+
+		void OnFileIsDirtyChanged(object sender, EventArgs e)
+		{
+			UpdateUndoStackIsOriginalFile();
+		}
+		
+		void UpdateUndoStackIsOriginalFile()
+		{
+			if (file.IsDirty) {
+				document.UndoStack.DiscardOriginalFileMarker();
+			} else {
+				document.UndoStack.MarkAsOriginalFile();
+			}
+		}
 	}
 }

src/Main/Base/Project/Workbench/File/FileModels.cs

@@ -19,7 +19,7 @@ namespace ICSharpCode.SharpDevelop.Workbench
 		/// <summary>
 		/// The text document file model provider.
 		/// </summary>
-		public static readonly IFileModelProvider<ICSharpCode.AvalonEdit.Document.TextDocument> TextDocument = new TextDocumentFileModelProvider();
+		public static readonly TextDocumentFileModelProvider TextDocument = new TextDocumentFileModelProvider();
 		
 		/// <summary>
 		/// The XDocument file model provider.

src/Main/Base/Project/Workbench/File/IFileModelProvider.cs

@@ -77,6 +77,15 @@ namespace ICSharpCode.SharpDevelop.Workbench
 		/// </summary>
 		void NotifyStale(OpenedFile file, T model);
 		
+		/// <summary>
+		/// Notifies the provider that a new model was loaded.
+		/// This method is called by OpenedFile.GetModel() after a Load() operation (unless Load() returned the existing stale model),
+		/// or by OpenedFile.ReplaceModel().
+		/// 
+		/// This method is intended to be used to set up the handling of the IsDirty flag.
+		/// </summary>
+		void NotifyLoaded(OpenedFile file, T model);
+		
 		/// <summary>
 		/// Notifies a model that it became unloaded.
 		/// This can happen due to:

src/Main/Base/Project/Workbench/File/OpenedFile.cs

@@ -70,6 +70,13 @@ namespace ICSharpCode.SharpDevelop.Workbench
 	/// <summary>
 	/// Represents an opened file.
 	/// </summary>
+	/// <remarks>
+	/// This class uses reference counting: the <c>AddReference()</c> and <c>ReleaseReference()</c>
+	/// methods are used to track an explicit reference count.
+	/// When the last reference is released, the opened file will be disposed.
+	/// View contents must maintain a reference to their opened files
+	/// (this usually happens via the AbstractViewContent.Files collection).
+	/// </remarks>
 	public abstract class OpenedFile : ICanBeDirty
 	{
 		abstract class ModelEntry
@@ -295,7 +302,7 @@ namespace ICSharpCode.SharpDevelop.Workbench
 		{
 			CheckDisposed();
 			foreach (var entry in entries) {
-				if (entry.Provider == modelProvider)
+				if (object.Equals(entry.Provider, modelProvider))
 					return (ModelEntry<T>)entry;
 			}
 			return null;
@@ -694,29 +701,29 @@ namespace ICSharpCode.SharpDevelop.Workbench
 			IsDirty = false;
 		}
 		
-//		/// <summary>
+		//		/// <summary>
-//		/// Called before saving the current view. This event is raised both when saving to disk and to memory (for switching between views).
+		//		/// Called before saving the current view. This event is raised both when saving to disk and to memory (for switching between views).
-//		/// </summary>
+		//		/// </summary>
-//		public event EventHandler SavingCurrentView;
+		//		public event EventHandler SavingCurrentView;
-//
+		//
-//		/// <summary>
+		//		/// <summary>
-//		/// Called after saving the current view. This event is raised both when saving to disk and to memory (for switching between views).
+		//		/// Called after saving the current view. This event is raised both when saving to disk and to memory (for switching between views).
-//		/// </summary>
+		//		/// </summary>
-//		public event EventHandler SavedCurrentView;
+		//		public event EventHandler SavedCurrentView;
 		
 		
 		void SaveCurrentViewToStream(Stream stream)
 		{
-//			if (SavingCurrentView != null)
+			//			if (SavingCurrentView != null)
-//				SavingCurrentView(this, EventArgs.Empty);
+			//				SavingCurrentView(this, EventArgs.Empty);
 			inSaveOperation = true;
 			try {
 				currentView.Save(this, stream);
 			} finally {
 				inSaveOperation = false;
 			}
-//			if (SavedCurrentView != null)
+			//			if (SavedCurrentView != null)
-//				SavedCurrentView(this, EventArgs.Empty);
+			//				SavedCurrentView(this, EventArgs.Empty);
 		}
 		
 		protected void SaveCurrentView()
@@ -736,7 +743,7 @@ namespace ICSharpCode.SharpDevelop.Workbench
 				return;
 			if (currentView != null) {
 				if (newView.SupportsSwitchToThisWithoutSaveLoad(this, currentView)
-				    || currentView.SupportsSwitchFromThisWithoutSaveLoad(this, newView))
+					|| currentView.SupportsSwitchFromThisWithoutSaveLoad(this, newView))
 				{
 					// switch without Save/Load
 					currentView.SwitchFromThisWithoutSaveLoad(this, newView);
@@ -820,5 +827,5 @@ namespace ICSharpCode.SharpDevelop.Workbench
 			}
 		}
 	}
-	 */
+	*/
 }

src/Main/Base/Project/Workbench/File/TextDocumentFileModelProvider.cs

@@ -15,9 +15,18 @@ using ICSharpCode.SharpDevelop.Widgets.MyersDiff;
 
 namespace ICSharpCode.SharpDevelop.Workbench
 {
-	sealed class TextDocumentFileModelProvider : IFileModelProvider<TextDocument>
+	public sealed class TextDocumentFileModelProvider : IFileModelProvider<TextDocument>
 	{
-		public TextDocument Load(OpenedFile file)
+		/// <summary>
+		/// Internal ctor: FileModels.TextDocument should be the only instance.
+		/// </summary>
+		internal TextDocumentFileModelProvider()
+		{
+		}
+		
+		// use explicit interface implementations because these methods are supposed to only
+		// be called from the OpenedFile infrastructure
+		TextDocument IFileModelProvider<TextDocument>.Load(OpenedFile file)
 		{
 			TextDocument document = file.GetModel(this, GetModelOptions.AllowStale | GetModelOptions.DoNotLoad);
 			var info = document != null ? document.GetFileModelInfo() : new DocumentFileModelInfo();
@@ -30,44 +39,28 @@ namespace ICSharpCode.SharpDevelop.Workbench
 			}
 			if (document != null) {
 				// Reload document
-				var diff = new MyersDiffAlgorithm(new StringSequence(document.Text), new StringSequence(textContent));
+				ReloadDocument(document, new StringTextSource(textContent));
-				info.isLoading = true;
+				info.IsStale = false;
-				try {
-					document.Replace(0, document.TextLength, textContent, ToOffsetChangeMap(diff.GetEdits()));
-					document.UndoStack.ClearAll();
-					info.IsStale = false;
-				} finally {
-					info.isLoading = false;
-				}
 			} else {
 				document = new TextDocument(textContent);
-				document.TextChanged += delegate { UpdateFileIsDirty(document, file, info); };
+				// Store info for the new document (necessary so that we don't forget the encoding we just used)
 				document.GetRequiredService<IServiceContainer>().AddService(typeof(DocumentFileModelInfo), info);
 			}
-			file.IsDirtyChanged += delegate { UpdateUndoStackIsOriginalFile(file, document); };
-			UpdateUndoStackIsOriginalFile(file, document);
 			return document;
 		}
 		
-		static void UpdateUndoStackIsOriginalFile(ICanBeDirty file, TextDocument document)
+		public void ReloadDocument(TextDocument document, ITextSource newContent)
-		{
-			if (file.IsDirty) {
-				document.UndoStack.DiscardOriginalFileMarker();
-			} else {
-				document.UndoStack.MarkAsOriginalFile();
-			}
-		}
-		
-		void UpdateFileIsDirty(TextDocument document, OpenedFile file, DocumentFileModelInfo info)
 		{
-			if (!info.isLoading) {
+			var info = document.GetFileModelInfo();
-				// Set dirty flag on OpenedFile according to UndoStack.IsOriginalFile
+			var diff = new MyersDiffAlgorithm(new StringSequence(document.Text), new StringSequence(newContent.Text));
-				if (document.UndoStack.IsOriginalFile && file.IsDirty) {
+			if (info != null)
-					// reset dirty marker
+				info.isLoading = true;
-					file.ReplaceModel(this, document, ReplaceModelMode.SetAsValid);
+			try {
-				} else if (!document.UndoStack.IsOriginalFile) {
+				document.Replace(0, document.TextLength, newContent, ToOffsetChangeMap(diff.GetEdits()));
-					file.MakeDirty(this);
+				document.UndoStack.ClearAll();
-				}
+			} finally {
+				if (info != null)
+					info.isLoading = false;
 			}
 		}
 		
@@ -87,14 +80,14 @@ namespace ICSharpCode.SharpDevelop.Workbench
 			return map;
 		}
 		
-		public void Save(OpenedFile file, TextDocument model, FileSaveOptions options)
+		void IFileModelProvider<TextDocument>.Save(OpenedFile file, TextDocument model, FileSaveOptions options)
 		{
 			MemoryStream ms = new MemoryStream();
 			SaveTo(ms, model, options);
 			file.ReplaceModel(FileModels.Binary, new BinaryFileModel(ms.ToArray()), ReplaceModelMode.TransferDirty);
 		}
 		
-		public void SaveCopyAs(OpenedFile file, TextDocument model, FileName outputFileName, FileSaveOptions options)
+		void IFileModelProvider<TextDocument>.SaveCopyAs(OpenedFile file, TextDocument model, FileName outputFileName, FileSaveOptions options)
 		{
 			using (Stream s = SD.FileSystem.OpenWrite(outputFileName)) {
 				SaveTo(s, model, options);
@@ -147,7 +140,7 @@ namespace ICSharpCode.SharpDevelop.Workbench
 			int r = MessageService.ShowCustomDialog(
 				"${res:Dialog.Options.IDEOptions.TextEditor.General.FontGroupBox.FileEncodingGroupBox}",
 				StringParser.Parse("${res:AvalonEdit.FileEncoding.EncodingCausesDataLoss}",
-				                   new StringTagPair("encoding", encoding.EncodingName)),
+					new StringTagPair("encoding", encoding.EncodingName)),
 				0, -1,
 				"${res:AvalonEdit.FileEncoding.EncodingCausesDataLoss.UseUTF8}",
 				"${res:AvalonEdit.FileEncoding.EncodingCausesDataLoss.Continue}");
@@ -159,19 +152,24 @@ namespace ICSharpCode.SharpDevelop.Workbench
 			return otherProvider == FileModels.Binary || FileModels.Binary.CanLoadFrom(otherProvider);
 		}
 		
-		public void NotifyRename(OpenedFile file, TextDocument model, FileName oldName, FileName newName)
+		void IFileModelProvider<TextDocument>.NotifyRename(OpenedFile file, TextDocument model, FileName oldName, FileName newName)
 		{
 			model.FileName = newName;
 		}
 		
-		public void NotifyStale(OpenedFile file, TextDocument model)
+		void IFileModelProvider<TextDocument>.NotifyStale(OpenedFile file, TextDocument model)
 		{
 			model.GetFileModelInfo().IsStale = true;
 		}
 		
-		public void NotifyUnloaded(OpenedFile file, TextDocument model)
+		void IFileModelProvider<TextDocument>.NotifyLoaded(OpenedFile file, TextDocument model)
 		{
-			model.GetFileModelInfo().IsStale = true;
+			model.GetFileModelInfo().NotifyLoaded(file, model);
+		}
+		
+		void IFileModelProvider<TextDocument>.NotifyUnloaded(OpenedFile file, TextDocument model)
+		{
+			model.GetFileModelInfo().NotifyUnloaded();
 		}
 	}
 }

src/Main/Base/Project/Workbench/File/XDocumentFileModelProvider.cs

@@ -16,9 +16,6 @@ namespace ICSharpCode.SharpDevelop.Workbench
 			using (Stream stream = file.GetModel(FileModels.Binary).OpenRead()) {
 				document = XDocument.Load(stream, LoadOptions.PreserveWhitespace);
 			}
-			document.Changed += delegate {
-				file.MakeDirty(this);
-			};
 			return document;
 		}
 		
@@ -47,6 +44,13 @@ namespace ICSharpCode.SharpDevelop.Workbench
 		{
 		}
 		
+		public void NotifyLoaded(OpenedFile file, XDocument model)
+		{
+			model.Changed += delegate {
+				file.MakeDirty(this);
+			};
+		}
+		
 		public void NotifyUnloaded(OpenedFile file, XDocument model)
 		{
 		}

src/Main/Base/Project/Workbench/IViewContent.cs

@@ -36,6 +36,13 @@ namespace ICSharpCode.SharpDevelop
 	/// </summary>
 	public interface IViewContent : IDisposable, ICanBeDirty, IServiceProvider
 	{
+		/// <summary>
+		/// Notifies the view content that it should (re-)load the file models.
+		/// This method is called by the SharpDevelop infrastructure whenever a view content
+		/// receives focus.
+		/// </summary>
+		void LoadModel();
+		
 		/// <summary>
 		/// This is the UI element for the view.
 		/// You can use both Windows.Forms and WPF controls.

src/Main/SharpDevelop/Workbench/WpfWorkbench.cs

@@ -31,15 +31,13 @@ using System.Windows.Input;
 using System.Windows.Interop;
 using System.Windows.Media;
 using System.Windows.Navigation;
-using System.Windows.Threading;
 
 using ICSharpCode.Core;
 using ICSharpCode.Core.Presentation;
 using ICSharpCode.SharpDevelop.Gui;
 using ICSharpCode.SharpDevelop.Parser;
-using ICSharpCode.SharpDevelop.Project;
-using ICSharpCode.SharpDevelop.Startup;
 using ICSharpCode.SharpDevelop.WinForms;
+using ICSharpCode.SharpDevelop.Startup;
 
 namespace ICSharpCode.SharpDevelop.Workbench
 {
@@ -263,10 +261,11 @@ namespace ICSharpCode.SharpDevelop.Workbench
 		public ICollection<IViewContent> PrimaryViewContents {
 			get {
 				SD.MainThread.VerifyAccess();
-				return (from window in WorkbenchWindowCollection
+				return (
-				        where window.ViewContents.Count > 0
+					from window in WorkbenchWindowCollection
-				        select window.ViewContents[0]
+					where window.ViewContents.Count > 0
-				       ).ToList().AsReadOnly();
+					select window.ViewContents[0]
+				).ToList().AsReadOnly();
 			}
 		}
 		
@@ -306,10 +305,10 @@ namespace ICSharpCode.SharpDevelop.Workbench
 						value.ActiveViewContentChanged += WorkbenchWindowActiveViewContentChanged;
 					}
 					
+					WorkbenchWindowActiveViewContentChanged(null, null);
 					if (ActiveWorkbenchWindowChanged != null) {
 						ActiveWorkbenchWindowChanged(this, EventArgs.Empty);
 					}
-					WorkbenchWindowActiveViewContentChanged(null, null);
 				}
 			}
 		}
@@ -319,10 +318,11 @@ namespace ICSharpCode.SharpDevelop.Workbench
 			if (workbenchLayout != null) {
 				// update ActiveViewContent
 				IWorkbenchWindow window = this.ActiveWorkbenchWindow;
-				if (window != null)
+				if (window != null) {
 					this.ActiveViewContent = window.ActiveViewContent;
-				else
+				} else {
 					this.ActiveViewContent = null;
+				}
 				
 				// update ActiveContent
 				this.ActiveContent = workbenchLayout.ActiveContent;
@@ -360,6 +360,11 @@ namespace ICSharpCode.SharpDevelop.Workbench
 				if (activeViewContent != value) {
 					activeViewContent = value;
 					
+					// Call LoadModel() before raising the event; this
+					// ensures that listeners to ActiveViewContentChanged
+					// see an up-to-date model.
+					if (value != null)
+						value.LoadModel();
 					if (ActiveViewContentChanged != null) {
 						ActiveViewContentChanged(this, EventArgs.Empty);
 					}