Use only one ChangeWatcher instance in split view.

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

@@ -19,10 +19,20 @@ namespace ICSharpCode.AvalonEdit.AddIn
 	{
 		IChangeWatcher changeWatcher;
 		
-		public ChangeMarkerMargin()
+		public ChangeMarkerMargin(IChangeWatcher changeWatcher)
 		{
-			changeWatcher = new DefaultChangeWatcher();
+			this.changeWatcher = changeWatcher;
-			changeWatcher.ChangeOccurred += new EventHandler(ChangeOccurred);
+			changeWatcher.ChangeOccurred += ChangeOccurred;
+		}
+		
+		bool disposed = false;
+		
+		public void Dispose()
+		{
+			if (!disposed) {
+				changeWatcher.ChangeOccurred -= ChangeOccurred;
+				disposed = true;
+			}
 		}
 		
 		protected override void OnRender(DrawingContext drawingContext)
@@ -31,13 +41,10 @@ namespace ICSharpCode.AvalonEdit.AddIn
 			TextView textView = this.TextView;
 			
 			if (textView != null && textView.VisualLinesValid) {
-				ITextEditor editor = textView.Services.GetService(typeof(ITextEditor)) as ITextEditor;
-				changeWatcher.Initialize(editor.Document);
-				
 				foreach (VisualLine line in textView.VisualLines) {
 					Rect rect = new Rect(0, line.VisualTop - textView.ScrollOffset.Y, 5, line.Height);
 					
-					LineChangeInfo info = changeWatcher.GetChange(editor.Document.GetLine(line.FirstDocumentLine.LineNumber));
+					LineChangeInfo info = changeWatcher.GetChange(line.FirstDocumentLine.LineNumber);
 					
 					switch (info.Change) {
 						case ChangeType.None:
@@ -65,7 +72,7 @@ namespace ICSharpCode.AvalonEdit.AddIn
 					
 					// special case for line 0
 					if (line.FirstDocumentLine.LineNumber == 1) {
-						info = changeWatcher.GetChange(null);
+						info = changeWatcher.GetChange(0);
 						
 						if (!string.IsNullOrEmpty(info.DeletedLinesAfterThisLine)) {
 							Point pt1 = new Point(5,  line.VisualTop - textView.ScrollOffset.Y - 4);
@@ -97,7 +104,7 @@ namespace ICSharpCode.AvalonEdit.AddIn
 				oldTextView.VisualLinesChanged -= VisualLinesChanged;
 				oldTextView.ScrollOffsetChanged -= ScrollOffsetChanged;
 			}
-			
+			base.OnTextViewChanged(oldTextView, newTextView);
 			if (newTextView != null) {
 				newTextView.VisualLinesChanged += VisualLinesChanged;
 				newTextView.ScrollOffsetChanged += ScrollOffsetChanged;
@@ -123,17 +130,5 @@ namespace ICSharpCode.AvalonEdit.AddIn
 		{
 			return new Size(5, 0);
 		}
-		
-		bool disposed = false;
-		
-		public void Dispose()
-		{
-			if (!disposed) {
-				OnTextViewChanged(TextView, null);
-				changeWatcher.Dispose();
-				changeWatcher = null;
-				disposed = true;
-			}
-		}
 	}
 }

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

@@ -48,6 +48,7 @@ namespace ICSharpCode.AvalonEdit.AddIn
 		GridSplitter gridSplitter;
 		readonly IconBarManager iconBarManager;
 		readonly TextMarkerService textMarkerService;
+		readonly IChangeWatcher changeWatcher;
 		ErrorPainter errorPainter;
 		
 		public CodeEditorView PrimaryTextEditor {
@@ -116,6 +117,7 @@ namespace ICSharpCode.AvalonEdit.AddIn
 					} else {
 						this.errorPainter.UpdateErrors();
 					}
+					changeWatcher.Initialize(this.DocumentAdapter);
 					
 					FetchParseInformation();
 				}
@@ -143,6 +145,7 @@ namespace ICSharpCode.AvalonEdit.AddIn
 			
 			textMarkerService = new TextMarkerService(this);
 			iconBarManager = new IconBarManager();
+			changeWatcher = new DefaultChangeWatcher();
 			
 			primaryTextEditor = CreateTextEditor();
 			primaryTextEditorAdapter = (CodeEditorAdapter)primaryTextEditor.TextArea.GetService(typeof(ITextEditor));
@@ -175,6 +178,9 @@ namespace ICSharpCode.AvalonEdit.AddIn
 				secondaryTextEditor.UpdateCustomizedHighlighting();
 		}
 		
+		/// <summary>
+		/// This method is called to create a new text editor view (=once for the primary editor; and whenever splitting the editor)
+		/// </summary>
 		protected virtual CodeEditorView CreateTextEditor()
 		{
 			CodeEditorView codeEditorView = new CodeEditorView();
@@ -199,7 +205,7 @@ namespace ICSharpCode.AvalonEdit.AddIn
 			textView.Services.AddService(typeof(IBookmarkMargin), iconBarManager);
 			codeEditorView.TextArea.LeftMargins.Insert(0, new IconBarMargin(iconBarManager));
 			
-			codeEditorView.TextArea.LeftMargins.Add(new ChangeMarkerMargin());
+			codeEditorView.TextArea.LeftMargins.Add(new ChangeMarkerMargin(changeWatcher));
 			
 			textView.Services.AddService(typeof(ISyntaxHighlighter), new AvalonEditSyntaxHighlighterAdapter(textView));
 			
@@ -221,8 +227,8 @@ namespace ICSharpCode.AvalonEdit.AddIn
 
 		protected virtual void DisposeTextEditor(CodeEditorView textEditor)
 		{
-			// detach IconBarMargin from IconBarManager
+			foreach (var d in textEditor.TextArea.LeftMargins.OfType<IDisposable>())
-			textEditor.TextArea.LeftMargins.OfType<IconBarMargin>().Single().TextView = null;
+				d.Dispose();
 			textEditor.Dispose();
 		}
 		

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

@@ -20,7 +20,6 @@ namespace ICSharpCode.AvalonEdit.AddIn
 {
 	public class DefaultChangeWatcher : IChangeWatcher, ILineTracker
 	{
-		WeakLineTracker lineTracker;
 		CompressingTreeList<LineChangeInfo> changeList;
 		IDocument document;
 		TextDocument textDocument;
@@ -35,12 +34,9 @@ namespace ICSharpCode.AvalonEdit.AddIn
 			}
 		}
 		
-		public LineChangeInfo GetChange(IDocumentLine line)
+		public LineChangeInfo GetChange(int lineNumber)
 		{
-			if (line == null)
+			return changeList[lineNumber];
-				return changeList[0];
-			
-			return changeList[line.LineNumber];
 		}
 		
 		public void Initialize(IDocument document)
@@ -49,19 +45,20 @@ namespace ICSharpCode.AvalonEdit.AddIn
 				return;
 			
 			this.document = document;
-			this.textDocument = ((TextView)document.GetService(typeof(TextView))).Document;
+			this.textDocument = (TextDocument)document.GetService(typeof(TextDocument));
 			this.changeList = new CompressingTreeList<LineChangeInfo>((x, y) => x.Equals(y));
 			
 			Stream baseFileStream = GetBaseVersion();
 			
 			// TODO : update baseDocument on VCS actions
 			if (baseFileStream != null) {
+				// ReadAll() is taking care of closing the stream
 				baseDocument = DocumentUtilitites.LoadReadOnlyDocumentFromBuffer(new StringTextBuffer(ReadAll(baseFileStream)));
 			}
 			
 			SetupInitialFileState(false);
 			
-			lineTracker = WeakLineTracker.Register(this.textDocument, this);
+			this.textDocument.LineTrackers.Add(this);
 			this.textDocument.UndoStack.PropertyChanged += UndoStackPropertyChanged;
 		}
 		
@@ -144,7 +141,7 @@ namespace ICSharpCode.AvalonEdit.AddIn
 		
 		void UndoStackPropertyChanged(object sender, PropertyChangedEventArgs e)
 		{
-			if (textDocument.UndoStack.IsOriginalFile)
+			if (e.PropertyName == "IsOriginalFile" && textDocument.UndoStack.IsOriginalFile)
 				SetupInitialFileState(true);
 		}
 		
@@ -185,7 +182,7 @@ namespace ICSharpCode.AvalonEdit.AddIn
 		public void Dispose()
 		{
 			if (!disposed) {
-				lineTracker.Deregister();
+				this.textDocument.LineTrackers.Remove(this);
 				this.textDocument.UndoStack.PropertyChanged -= UndoStackPropertyChanged;
 				disposed = true;
 			}

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

@@ -18,7 +18,7 @@ namespace ICSharpCode.AvalonEdit.AddIn
 	/// <summary>
 	/// Icon bar: contains breakpoints and other icons.
 	/// </summary>
-	public class IconBarMargin : AbstractMargin
+	public class IconBarMargin : AbstractMargin, IDisposable
 	{
 		readonly IconBarManager manager;
 		
@@ -49,6 +49,11 @@ namespace ICSharpCode.AvalonEdit.AddIn
 		{
 			InvalidateVisual();
 		}
+		
+		public virtual void Dispose()
+		{
+			this.TextView = null; // detach from TextView (will also detach from manager)
+		}
 		#endregion
 		
 		/// <inheritdoc/>

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

@@ -9,11 +9,12 @@ namespace ICSharpCode.AvalonEdit.AddIn
 	public interface IChangeWatcher : IDisposable
 	{
 		event EventHandler ChangeOccurred;
+		
 		/// <summary>
 		/// Returns the change information for a given line.
-		/// Pass null to get the changes before the first line.
+		/// Pass 0 to get the changes before the first line.
 		/// </summary>
-		LineChangeInfo GetChange(IDocumentLine line);
+		LineChangeInfo GetChange(int lineNumber);
 		void Initialize(IDocument document);
 	}
 	

src/AddIns/DisplayBindings/AvalonEdit.AddIn/Src/MyersDiff/DocumentSequence.cs

@@ -15,6 +15,8 @@ namespace ICSharpCode.AvalonEdit.AddIn.MyersDiff
 		{
 			this.hashes = new int[document.TotalNumberOfLines];
 			
+			// Construct a perfect hash for the document lines, and store the 'hash code'
+			// (really just a unique identifier for each line content) in our array.
 			for (int i = 1; i <= document.TotalNumberOfLines; i++) {
 				string text = document.GetLine(i).Text;
 				int hash;