gistfile1.diff

@@ -369,14 +369,14 @@
 			if (pos < 0)
 				return;
 			
-			editor.Document.BeginAtomicUndo ();
-			var oldCaret = editor.Caret.Offset;
-			
-			var inserted = editor.Insert (pos, editor.EolMarker + directive.ToString ());
-			if (preserveCaretPosition) {
-				editor.Caret.Offset = (pos < oldCaret)? oldCaret + inserted : oldCaret;
+			using (var undo = editor.OpenUndoGroup ()) {
+				var oldCaret = editor.Caret.Offset;
+				
+				var inserted = editor.Insert (pos, editor.EolMarker + directive.ToString ());
+				if (preserveCaretPosition) {
+					editor.Caret.Offset = (pos < oldCaret)? oldCaret + inserted : oldCaret;
+				}
 			}
-			editor.Document.EndAtomicUndo ();
 		}
 		
 		DirectiveNode GetRegisterInsertionPointNode ()

@@ -77,11 +77,11 @@
 		{
 			//insert the method name
 			MonoDevelop.Ide.Gui.Content.IEditableTextBuffer buf = window.CompletionWidget as MonoDevelop.Ide.Gui.Content.IEditableTextBuffer;
-			if (buf != null) {
-				buf.BeginAtomicUndo ();
-				buf.DeleteText (window.CodeCompletionContext.TriggerOffset, buf.CursorPosition - window.CodeCompletionContext.TriggerOffset);
-				buf.InsertText (buf.CursorPosition, methodInfo.Name);
-				buf.EndAtomicUndo ();
+			if (buf != null) {
+				using (var undo = buf.OpenUndoGroup ()) {
+					buf.DeleteText (window.CodeCompletionContext.TriggerOffset, buf.CursorPosition - window.CodeCompletionContext.TriggerOffset);
+					buf.InsertText (buf.CursorPosition, methodInfo.Name);
+				}
 			}
 			
 			//generate the codebehind method

@@ -72,21 +72,20 @@
 		{
 			MonoDevelop.Ide.Gui.Content.IEditableTextBuffer buf = window.CompletionWidget as MonoDevelop.Ide.Gui.Content.IEditableTextBuffer;
 			if (buf != null) {
-				buf.BeginAtomicUndo ();
-				
-				int deleteStartOffset = window.CodeCompletionContext.TriggerOffset;
-				if (text.StartsWith (docTypeStart)) {
-					int start = window.CodeCompletionContext.TriggerOffset - docTypeStart.Length;
-					if (start >= 0) {
-						string readback = buf.GetText (start, window.CodeCompletionContext.TriggerOffset);
-						if (string.Compare (readback, docTypeStart, StringComparison.OrdinalIgnoreCase) == 0)
-							deleteStartOffset -= docTypeStart.Length;
+				using (var undo = buf.OpenUndoGroup ()) {
+					int deleteStartOffset = window.CodeCompletionContext.TriggerOffset;
+					if (text.StartsWith (docTypeStart)) {
+						int start = window.CodeCompletionContext.TriggerOffset - docTypeStart.Length;
+						if (start >= 0) {
+							string readback = buf.GetText (start, window.CodeCompletionContext.TriggerOffset);
+							if (string.Compare (readback, docTypeStart, StringComparison.OrdinalIgnoreCase) == 0)
+								deleteStartOffset -= docTypeStart.Length;
+						}
 					}
-				}
-				
-				buf.DeleteText (deleteStartOffset, buf.CursorPosition - deleteStartOffset);
-				buf.InsertText (buf.CursorPosition, text);
-				buf.EndAtomicUndo ();
+					
+					buf.DeleteText (deleteStartOffset, buf.CursorPosition - deleteStartOffset);
+					buf.InsertText (buf.CursorPosition, text);
+				}
 			}
 		}
 	}

@@ -416,8 +416,6 @@
 							string indent = textEditorData.Document.GetLineIndent (completionContext.TriggerLine);
 							AppendSummary (generatedComment, indent, out newCursorOffset);
 						}
-						textEditorData.Document.EndAtomicUndo ();
-						textEditorData.Document.BeginAtomicUndo ();
 						textEditorData.Insert (cursor, generatedComment.ToString ());
 						textEditorData.Caret.Offset = cursor + newCursorOffset;
 						return null;

@@ -148,11 +148,8 @@
 			var changes = new List<ICSharpCode.NRefactory.CSharp.Refactoring.Action> ();
 			changes.AddRange (formattingVisitor.Changes.
 				Where (c => (startOffset <= c.Offset && c.Offset < endOffset)));
-			try {
-				data.Document.BeginAtomicUndo ();
+			using (var undo = data.OpenUndoGroup ()) {
 				MDRefactoringContext.MdScript.RunActions (changes, null);
-			} finally {
-				data.Document.EndAtomicUndo ();
 			}
 		}
 

@@ -211,14 +211,12 @@
 
 				int guessedOffset = GuessSemicolonInsertionOffset (textEditorData, curLine);
 				if (guessedOffset != textEditorData.Caret.Offset) {
-					if (textEditorData.Document.IsInAtomicUndo) {
-						textEditorData.Document.EndAtomicUndo ();
-						textEditorData.Document.BeginAtomicUndo ();
+					using (var undo = textEditorData.OpenUndoGroup ()) {
+						textEditorData.Remove (textEditorData.Caret.Offset - 1, 1);
+						textEditorData.Caret.Offset = guessedOffset;
+						lastInsertedSemicolon = textEditorData.Caret.Offset + 1;
+						retval = base.KeyPress (key, keyChar, modifier);
 					}
-					textEditorData.Remove (textEditorData.Caret.Offset - 1, 1);
-					textEditorData.Caret.Offset = guessedOffset;
-					lastInsertedSemicolon = textEditorData.Caret.Offset + 1;
-					retval = base.KeyPress (key, keyChar, modifier);
 				}
 				return retval;
 			}

@@ -127,14 +127,12 @@
 				var lastOffset = data.Editor.Caret.Offset;
 				changes.RemoveAll (c => ((TextReplaceAction)c).Offset > lastOffset);
 			}
-			try {
-				data.Editor.Document.BeginAtomicUndo ();
+			
+			using (var undo = data.Editor.OpenUndoGroup ()) {
 				MDRefactoringContext.MdScript.RunActions (changes, null);
 				
 				foreach (int line in lines)
 					data.Editor.Document.CommitLineUpdate (line);
-			} finally {
-				data.Editor.Document.EndAtomicUndo ();
 			}
 			stubData.Dispose ();
 		}

@@ -94,9 +94,9 @@
 				}
 			}
 			docs.Sort ((a, b) => b.Key.CompareTo (a.Key));
-			data.Document.BeginAtomicUndo ();
-			docs.ForEach (doc => data.Insert (doc.Key, doc.Value));
-			data.Document.EndAtomicUndo ();
+			using (var undo = data.OpenUndoGroup ()) {
+				docs.ForEach (doc => data.Insert (doc.Key, doc.Value));
+			}
 		}
 		
 		static bool NeedsDocumentation (TextEditorData data, IMember member)

@@ -80,16 +80,9 @@
 			
 			int offset = textEditorData.Caret.Offset;
 			
-			bool wasInAtomicUndo = textEditorData.Document.IsInAtomicUndo;
-			if (wasInAtomicUndo)
-				textEditorData.Document.EndAtomicUndo ();
-			
 			int insertedLength = textEditorData.Insert (offset, documentationEmpty);
 			// important to set the caret position here for the undo step
 			textEditorData.Caret.Offset = offset + insertedLength;
-			
-			if (wasInAtomicUndo)
-				textEditorData.Document.BeginAtomicUndo ();
 			
 			insertedLength = textEditorData.Replace (offset, insertedLength, documentation);
 			textEditorData.Caret.Offset = offset + insertedLength;

@@ -89,14 +89,9 @@
 			poEditorWidget.Redo ();
 		}
 		
-		void IUndoHandler.BeginAtomicUndo ()
+		IDisposable IUndoHandler.OpenUndoGroup ()
 		{
-			poEditorWidget.BeginAtomicUndo ();
-		}
-		
-		void IUndoHandler.EndAtomicUndo ()
-		{
-			poEditorWidget.EndAtomicUndo ();
+			return poEditorWidget.OpenUndoGroup ();
 		}
 		
 		bool IUndoHandler.EnableUndo {

@@ -1267,12 +1267,16 @@
 			undoStack.Push (change);
 		}
 		
-		public void BeginAtomicUndo ()
+		class DisposeStub : IDisposable
 		{
+			public void Dispose ()
+			{
+			}
 		}
 		
-		public void EndAtomicUndo ()
+		public IDisposable OpenUndoGroup ()
 		{
+			return new DisposeStub ();
 		}
 		
 		public bool EnableUndo {

@@ -94,18 +94,31 @@
 			hexEditor.HexEditorData.Redo ();
 		}
 		
-		
-		void IUndoHandler.BeginAtomicUndo ()
+		class UndoGroup : IDisposable
 		{
-			hexEditor.HexEditorData.BeginAtomicUndo ();
-		}
-		
+			HexEditorData data;
+			
+			public UndoGroup (HexEditorData data)
+			{
+				if (data == null)
+					throw new ArgumentNullException ("data");
+				this.data = data;
+				data.BeginAtomicUndo ();
+			}
+			
+			public void Dispose ()
+			{
+				if (data != null) {
+					data.EndAtomicUndo ();
+					data = null;
+				}
+			}
+		}	
 		
-		void IUndoHandler.EndAtomicUndo ()
+		IDisposable IUndoHandler.OpenUndoGroup ()
 		{
-			hexEditor.HexEditorData.EndAtomicUndo ();
+			return new UndoGroup (hexEditor.HexEditorData);
 		}
-		
 		
 		bool IUndoHandler.EnableUndo {
 			get {

@@ -86,13 +86,16 @@
 		}
 		
 		static List<TextEditorData> textEditorDatas = new List<TextEditorData> ();
+		static List<IDisposable> undoGroups = new List<IDisposable> ();
+		
 		public static void FinishRefactoringOperation ()
 		{
 			foreach (TextEditorData data in textEditorDatas) {
-				data.Document.EndAtomicUndo ();
 				data.Document.CommitUpdateAll ();
 			}
 			textEditorDatas.Clear ();
+			undoGroups.ForEach (grp => grp.Dispose ());
+			undoGroups.Clear ();
 		}
 		
 		internal static TextEditorData GetTextEditorData (string fileName)
@@ -104,7 +107,7 @@
 					TextEditorData result = doc.Editor;
 					if (result != null) {
 						textEditorDatas.Add (result);
-						result.Document.BeginAtomicUndo ();
+						undoGroups.Add (result.OpenUndoGroup ());
 						return result;
 					}
 				}

@@ -380,6 +380,7 @@
 					skipChar = null;
 			}
 			char insertionChar = '\0';
+			IDisposable undoGroup = null;
 			if (skipChar == null && Options.AutoInsertMatchingBracket && braceIndex >= 0) {
 				if (!inStringOrComment) {
 					char closingBrace = closingBrackets [braceIndex];
@@ -396,7 +397,7 @@
 
 					if (count >= 0) {
 						startedAtomicOperation = true;
-						Document.BeginAtomicUndo ();
+						undoGroup = Document.OpenUndoGroup ();
 						GetTextEditorData ().EnsureCaretIsNotVirtual ();
 						
 						int offset = Caret.Offset;
@@ -409,7 +410,7 @@
 					char charBefore = Document.GetCharAt (Caret.Offset - 1);
 					if (!inString && !inComment && !inChar && ch == '"' && charBefore != '\\') {
 						startedAtomicOperation = true;
-						Document.BeginAtomicUndo ();
+						undoGroup = Document.OpenUndoGroup ();
 						GetTextEditorData ().EnsureCaretIsNotVirtual ();
 						insertionChar = '"';
 						int offset = Caret.Offset;
@@ -436,8 +437,8 @@
 						HitReturn ();
 				}
 			}
-			if (startedAtomicOperation)
-				Document.EndAtomicUndo ();
+			if (undoGroup != null)
+				undoGroup.Dispose ();
 			return templateInserted || result;
 		}
 		
@@ -667,39 +668,39 @@
 		
 		internal void InsertTemplate (CodeTemplate template, MonoDevelop.Ide.Gui.Document document)
 		{
-			Document.BeginAtomicUndo ();
-			var result = template.InsertTemplateContents (document);
-			var tle = new TextLinkEditMode (this, result.InsertPosition, result.TextLinks);
-			
-			if (PropertyService.Get ("OnTheFlyFormatting", false)) {
-				var prettyPrinter = CodeFormatterService.GetFormatter (Document.MimeType);
-				if (prettyPrinter != null) {
-					int endOffset = result.InsertPosition + result.Code.Length;
-					string oldText = Document.GetTextAt (result.InsertPosition, result.Code.Length);
-					var policies = document.Project != null ? document.Project.Policies : null;
-					string text = prettyPrinter.FormatText (policies, Document.Text, result.InsertPosition, endOffset);
-					
-					if (text != null)
-						Replace (result.InsertPosition, result.Code.Length, text);
-					else
-						//if formatting failed, just use the unformatted text
-						text = oldText;
-					
-					Caret.Offset = result.InsertPosition + TranslateOffset (oldText, text, Caret.Offset - result.InsertPosition);
-					foreach (TextLink textLink in tle.Links) {
-						foreach (ISegment segment in textLink.Links) {
-							segment.Offset = TranslateOffset (oldText, text, segment.Offset);
+			using (var undo = Document.OpenUndoGroup ()) {
+				var result = template.InsertTemplateContents (document);
+				var tle = new TextLinkEditMode (this, result.InsertPosition, result.TextLinks);
+				
+				if (PropertyService.Get ("OnTheFlyFormatting", false)) {
+					var prettyPrinter = CodeFormatterService.GetFormatter (Document.MimeType);
+					if (prettyPrinter != null) {
+						int endOffset = result.InsertPosition + result.Code.Length;
+						string oldText = Document.GetTextAt (result.InsertPosition, result.Code.Length);
+						var policies = document.Project != null ? document.Project.Policies : null;
+						string text = prettyPrinter.FormatText (policies, Document.Text, result.InsertPosition, endOffset);
+						
+						if (text != null)
+							Replace (result.InsertPosition, result.Code.Length, text);
+						else
+							//if formatting failed, just use the unformatted text
+							text = oldText;
+						
+						Caret.Offset = result.InsertPosition + TranslateOffset (oldText, text, Caret.Offset - result.InsertPosition);
+						foreach (TextLink textLink in tle.Links) {
+							foreach (ISegment segment in textLink.Links) {
+								segment.Offset = TranslateOffset (oldText, text, segment.Offset);
+							}
 						}
 					}
 				}
-			}
-			
-			if (tle.ShouldStartTextLinkMode) {
-				tle.OldMode = CurrentMode;
-				tle.StartMode ();
-				CurrentMode = tle;
+				
+				if (tle.ShouldStartTextLinkMode) {
+					tle.OldMode = CurrentMode;
+					tle.StartMode ();
+					CurrentMode = tle;
+				}
 			}
-			Document.EndAtomicUndo ();
 		}
 		
 		static int TranslateOffset (string baseInput, string formattedInput, int offset)
@@ -1066,11 +1067,8 @@
 		[CommandHandler (MonoDevelop.Ide.Commands.EditCommands.JoinWithNextLine)]
 		internal void JoinLines ()
 		{
-			try {
-				Document.BeginAtomicUndo ();
+			using (var undo = Document.OpenUndoGroup ()) {
 				RunAction (Mono.TextEditor.Vi.ViActions.Join);
-			} finally {
-				Document.EndAtomicUndo ();
 			}
 		}
 		

@@ -307,31 +307,31 @@
 			DisposeErrorMarkers (); // disposes messageBubbleCache as well.
 			if (IdeApp.Preferences.ShowMessageBubbles == ShowMessageBubbles.Never)
 				return;
-			widget.Document.BeginAtomicUndo ();
-			if (messageBubbleCache != null)
-				messageBubbleCache.Dispose ();
-			messageBubbleCache = new MessageBubbleCache (widget.TextEditor);
-			
-			foreach (Task task in tasks) {
-				if (task.Severity == TaskSeverity.Error || task.Severity == TaskSeverity.Warning) {
-					if (IdeApp.Preferences.ShowMessageBubbles == ShowMessageBubbles.ForErrors && task.Severity == TaskSeverity.Warning)
-						continue;
-					LineSegment lineSegment = widget.Document.GetLine (task.Line);
-					if (lineSegment == null)
-						continue;
-					var marker = currentErrorMarkers.FirstOrDefault (m => m.LineSegment == lineSegment);
-					if (marker != null) {
-						marker.AddError (task.Severity == TaskSeverity.Error, task.Description);
-						continue;
+			using (var undo = Document.OpenUndoGroup ()) {
+				if (messageBubbleCache != null)
+					messageBubbleCache.Dispose ();
+				messageBubbleCache = new MessageBubbleCache (widget.TextEditor);
+				
+				foreach (Task task in tasks) {
+					if (task.Severity == TaskSeverity.Error || task.Severity == TaskSeverity.Warning) {
+						if (IdeApp.Preferences.ShowMessageBubbles == ShowMessageBubbles.ForErrors && task.Severity == TaskSeverity.Warning)
+							continue;
+						LineSegment lineSegment = widget.Document.GetLine (task.Line);
+						if (lineSegment == null)
+							continue;
+						var marker = currentErrorMarkers.FirstOrDefault (m => m.LineSegment == lineSegment);
+						if (marker != null) {
+							marker.AddError (task.Severity == TaskSeverity.Error, task.Description);
+							continue;
+						}
+						MessageBubbleTextMarker errorTextMarker = new MessageBubbleTextMarker (messageBubbleCache, task, lineSegment, task.Severity == TaskSeverity.Error, task.Description);
+						currentErrorMarkers.Add (errorTextMarker);
+						
+						errorTextMarker.IsVisible =  !IdeApp.Preferences.DefaultHideMessageBubbles;
+						widget.Document.AddMarker (lineSegment, errorTextMarker, false);
 					}
-					MessageBubbleTextMarker errorTextMarker = new MessageBubbleTextMarker (messageBubbleCache, task, lineSegment, task.Severity == TaskSeverity.Error, task.Description);
-					currentErrorMarkers.Add (errorTextMarker);
-					
-					errorTextMarker.IsVisible =  !IdeApp.Preferences.DefaultHideMessageBubbles;
-					widget.Document.AddMarker (lineSegment, errorTextMarker, false);
 				}
 			}
-			widget.Document.EndAtomicUndo ();
 			widget.TextEditor.QueueDraw ();
 		}
 		
@@ -386,10 +386,10 @@
 			if (PropertyService.Get ("AutoFormatDocumentOnSave", false)) {
 				var formatter = CodeFormatterService.GetFormatter (Document.MimeType);
 				if (formatter != null && formatter.SupportsOnTheFlyFormatting) {
-					TextEditor.Document.BeginAtomicUndo ();
-					var policies = Project != null ? Project.Policies : null;
-					formatter.OnTheFlyFormat (policies, TextEditor.GetTextEditorData (), 0, Document.Length);
-					TextEditor.Document.EndAtomicUndo ();
+					using (var undo = TextEditor.OpenUndoGroup ()) {
+						var policies = Project != null ? Project.Policies : null;
+						formatter.OnTheFlyFormat (policies, TextEditor.GetTextEditorData (), 0, Document.Length);
+					}
 				}
 			}
 
@@ -1131,15 +1131,12 @@
 			this.Document.Redo ();
 		}
 		
-		public void BeginAtomicUndo ()
-		{
-			this.Document.BeginAtomicUndo ();
-		}
-		public void EndAtomicUndo ()
+		
+		public IDisposable OpenUndoGroup ()
 		{
-			this.Document.EndAtomicUndo ();
+			return Document.OpenUndoGroup ();
 		}
-			
+		
 		public string SelectedText { 
 			get {
 				return TextEditor.IsSomethingSelected ? Document.GetTextAt (TextEditor.SelectionRange) : "";
@@ -1490,26 +1487,26 @@
 			
 			triggerOffset += data.EnsureCaretIsNotVirtual ();
 			if (blockMode) {
-				data.Document.BeginAtomicUndo ();
+				using (var undo = data.OpenUndoGroup ()) {
 
-				int minLine = data.MainSelection.MinLine;
-				int maxLine = data.MainSelection.MaxLine;
-				int column = triggerOffset - data.Document.GetLineByOffset (triggerOffset).Offset;
-				for (int lineNumber = minLine; lineNumber <= maxLine; lineNumber++) {
-					LineSegment lineSegment = data.Document.GetLine (lineNumber);
-					if (lineSegment == null)
-						continue;
-					int offset = lineSegment.Offset + column;
-					data.Replace (offset, length, complete_word);
+					int minLine = data.MainSelection.MinLine;
+					int maxLine = data.MainSelection.MaxLine;
+					int column = triggerOffset - data.Document.GetLineByOffset (triggerOffset).Offset;
+					for (int lineNumber = minLine; lineNumber <= maxLine; lineNumber++) {
+						LineSegment lineSegment = data.Document.GetLine (lineNumber);
+						if (lineSegment == null)
+							continue;
+						int offset = lineSegment.Offset + column;
+						data.Replace (offset, length, complete_word);
+					}
+					data.Caret.Offset = triggerOffset + idx;
+					int minColumn = System.Math.Min (data.MainSelection.Anchor.Column, data.MainSelection.Lead.Column);
+					data.MainSelection.Anchor = new DocumentLocation (data.Caret.Line == minLine ? maxLine : minLine, minColumn);
+					data.MainSelection.Lead = new DocumentLocation (data.Caret.Line, TextEditor.Caret.Column);
+					
+					data.Document.CommitMultipleLineUpdate (data.MainSelection.MinLine, data.MainSelection.MaxLine);
+					data.Caret.PreserveSelection = false;
 				}
-				data.Caret.Offset = triggerOffset + idx;
-				int minColumn = System.Math.Min (data.MainSelection.Anchor.Column, data.MainSelection.Lead.Column);
-				data.MainSelection.Anchor = new DocumentLocation (data.Caret.Line == minLine ? maxLine : minLine, minColumn);
-				data.MainSelection.Lead = new DocumentLocation (data.Caret.Line, TextEditor.Caret.Column);
-				
-				data.Document.CommitMultipleLineUpdate (data.MainSelection.MinLine, data.MainSelection.MaxLine);
-				data.Caret.PreserveSelection = false;
-				data.Document.EndAtomicUndo ();
 			} else {
 				data.Replace (triggerOffset, length, complete_word);
 				data.Caret.Offset = triggerOffset + idx;
@@ -1909,12 +1906,12 @@
 			var policies = Project != null ? Project.Policies : null;
 			var editorData = TextEditor.GetTextEditorData ();
 			if (TextEditor.IsSomethingSelected) {
-				TextEditor.Document.BeginAtomicUndo ();
-				int max = TextEditor.MainSelection.MaxLine;
-				for (int i = TextEditor.MainSelection.MinLine; i <= max; i++) {
-					formatter.CorrectIndenting (policies, editorData, i);
+				using (var undo = TextEditor.OpenUndoGroup ()) {
+					int max = TextEditor.MainSelection.MaxLine;
+					for (int i = TextEditor.MainSelection.MinLine; i <= max; i++) {
+						formatter.CorrectIndenting (policies, editorData, i);
+					}
 				}
-				TextEditor.Document.EndAtomicUndo ();
 			} else {
 				formatter.CorrectIndenting (policies, editorData, TextEditor.Caret.Line);
 			}

@@ -1380,34 +1380,33 @@
 			string blockStart = blockStarts[0];
 			string blockEnd = blockEnds[0];
 
-			Document.BeginAtomicUndo ();
-			LineSegment startLine;
-			LineSegment endLine;
-
-			if (TextEditor.IsSomethingSelected) {
-				startLine = Document.GetLineByOffset (textEditor.SelectionRange.Offset);
-				endLine = Document.GetLineByOffset (textEditor.SelectionRange.EndOffset);
-			} else {
-				startLine = endLine = Document.GetLine (textEditor.Caret.Line);
-			}
-			string startLineText = Document.GetTextAt (startLine.Offset, startLine.EditableLength);
-			string endLineText = Document.GetTextAt (endLine.Offset, endLine.EditableLength);
-			if (startLineText.StartsWith (blockStart) && endLineText.EndsWith (blockEnd)) {
-				textEditor.Remove (endLine.Offset + endLine.EditableLength - blockEnd.Length, blockEnd.Length);
-				textEditor.Remove (startLine.Offset, blockStart.Length);
+			using (var undo = Document.OpenUndoGroup ()) {
+				LineSegment startLine;
+				LineSegment endLine;
+	
 				if (TextEditor.IsSomethingSelected) {
-					TextEditor.SelectionAnchor -= blockEnd.Length;
+					startLine = Document.GetLineByOffset (textEditor.SelectionRange.Offset);
+					endLine = Document.GetLineByOffset (textEditor.SelectionRange.EndOffset);
+				} else {
+					startLine = endLine = Document.GetLine (textEditor.Caret.Line);
 				}
-			} else {
-				textEditor.Insert (endLine.Offset + endLine.EditableLength, blockEnd);
-				textEditor.Insert (startLine.Offset, blockStart);
-				if (TextEditor.IsSomethingSelected) {
-					TextEditor.SelectionAnchor += blockEnd.Length;
+				string startLineText = Document.GetTextAt (startLine.Offset, startLine.EditableLength);
+				string endLineText = Document.GetTextAt (endLine.Offset, endLine.EditableLength);
+				if (startLineText.StartsWith (blockStart) && endLineText.EndsWith (blockEnd)) {
+					textEditor.Remove (endLine.Offset + endLine.EditableLength - blockEnd.Length, blockEnd.Length);
+					textEditor.Remove (startLine.Offset, blockStart.Length);
+					if (TextEditor.IsSomethingSelected) {
+						TextEditor.SelectionAnchor -= blockEnd.Length;
+					}
+				} else {
+					textEditor.Insert (endLine.Offset + endLine.EditableLength, blockEnd);
+					textEditor.Insert (startLine.Offset, blockStart);
+					if (TextEditor.IsSomethingSelected) {
+						TextEditor.SelectionAnchor += blockEnd.Length;
+					}
+					
 				}
-				
 			}
-			
-			Document.EndAtomicUndo ();
 		}
 		
 		public void ToggleCodeComment ()
@@ -1470,32 +1469,32 @@
 			LineSegment anchorLine   = TextEditor.IsSomethingSelected ? TextEditor.Document.GetLineByOffset (TextEditor.SelectionAnchor) : null;
 			int         anchorColumn = TextEditor.IsSomethingSelected ? TextEditor.SelectionAnchor - anchorLine.Offset : -1;
 			
-			Document.BeginAtomicUndo ();
-			foreach (LineSegment line in TextEditor.SelectedLines) {
-				TextEditor.Insert (line.Offset, commentTag);
-			}
-			if (TextEditor.IsSomethingSelected) {
-				if (TextEditor.SelectionAnchor < TextEditor.Caret.Offset) {
-					if (anchorColumn != 0) 
-						TextEditor.SelectionAnchor = System.Math.Min (anchorLine.Offset + anchorLine.EditableLength, System.Math.Max (anchorLine.Offset, TextEditor.SelectionAnchor + commentTag.Length));
-				} else {
-					if (anchorColumn != 0) {
-						TextEditor.SelectionAnchor = System.Math.Min (anchorLine.Offset + anchorLine.EditableLength, System.Math.Max (anchorLine.Offset, anchorLine.Offset + anchorColumn + commentTag.Length));
+			using (var undo = Document.OpenUndoGroup ()) {
+				foreach (LineSegment line in TextEditor.SelectedLines) {
+					TextEditor.Insert (line.Offset, commentTag);
+				}
+				if (TextEditor.IsSomethingSelected) {
+					if (TextEditor.SelectionAnchor < TextEditor.Caret.Offset) {
+						if (anchorColumn != 0) 
+							TextEditor.SelectionAnchor = System.Math.Min (anchorLine.Offset + anchorLine.EditableLength, System.Math.Max (anchorLine.Offset, TextEditor.SelectionAnchor + commentTag.Length));
 					} else {
-//						TextEditor.SelectionAnchor = anchorLine.Offset;
+						if (anchorColumn != 0) {
+							TextEditor.SelectionAnchor = System.Math.Min (anchorLine.Offset + anchorLine.EditableLength, System.Math.Max (anchorLine.Offset, anchorLine.Offset + anchorColumn + commentTag.Length));
+						} else {
+	//						TextEditor.SelectionAnchor = anchorLine.Offset;
+						}
 					}
+				}
+				
+				if (TextEditor.Caret.Column != 0) {
+					TextEditor.Caret.PreserveSelection = true;
+					TextEditor.Caret.Column += commentTag.Length;
+					TextEditor.Caret.PreserveSelection = false;
 				}
-			}
-			
-			if (TextEditor.Caret.Column != 0) {
-				TextEditor.Caret.PreserveSelection = true;
-				TextEditor.Caret.Column += commentTag.Length;
-				TextEditor.Caret.PreserveSelection = false;
+				
+				if (TextEditor.IsSomethingSelected) 
+					TextEditor.ExtendSelectionTo (TextEditor.Caret.Offset);
 			}
-			
-			if (TextEditor.IsSomethingSelected) 
-				TextEditor.ExtendSelectionTo (TextEditor.Caret.Offset);
-			Document.EndAtomicUndo ();
 			Document.CommitMultipleLineUpdate (startLineNr, endLineNr);
 		}
 		
@@ -1508,40 +1507,39 @@
 			LineSegment anchorLine   = TextEditor.IsSomethingSelected ? TextEditor.Document.GetLineByOffset (TextEditor.SelectionAnchor) : null;
 			int         anchorColumn = TextEditor.IsSomethingSelected ? TextEditor.SelectionAnchor - anchorLine.Offset : -1;
 			
-			Document.BeginAtomicUndo ();
-			int first = -1;
-			int last  = 0;
-			foreach (LineSegment line in TextEditor.SelectedLines) {
-				string text = Document.GetTextAt (line);
-				string trimmedText = text.TrimStart ();
-				int length = 0;
-				if (trimmedText.StartsWith (commentTag)) {
-					TextEditor.Remove (line.Offset + (text.Length - trimmedText.Length), commentTag.Length);
-					length = commentTag.Length;
+			using (var undo = Document.OpenUndoGroup ()) {
+				int first = -1;
+				int last  = 0;
+				foreach (LineSegment line in TextEditor.SelectedLines) {
+					string text = Document.GetTextAt (line);
+					string trimmedText = text.TrimStart ();
+					int length = 0;
+					if (trimmedText.StartsWith (commentTag)) {
+						TextEditor.Remove (line.Offset + (text.Length - trimmedText.Length), commentTag.Length);
+						length = commentTag.Length;
+					}
+					last = length;
+					if (first < 0)
+						first = last;
+				}
+				
+				if (TextEditor.IsSomethingSelected) {
+					if (TextEditor.SelectionAnchor < TextEditor.Caret.Offset) {
+						TextEditor.SelectionAnchor = System.Math.Min (anchorLine.Offset + anchorLine.EditableLength, System.Math.Max (anchorLine.Offset, TextEditor.SelectionAnchor - first));
+					} else {
+						TextEditor.SelectionAnchor = System.Math.Min (anchorLine.Offset + anchorLine.EditableLength, System.Math.Max (anchorLine.Offset, anchorLine.Offset + anchorColumn - last));
+					}
 				}
-				last = length;
-				if (first < 0)
-					first = last;
-			}
-			
-			if (TextEditor.IsSomethingSelected) {
-				if (TextEditor.SelectionAnchor < TextEditor.Caret.Offset) {
-					TextEditor.SelectionAnchor = System.Math.Min (anchorLine.Offset + anchorLine.EditableLength, System.Math.Max (anchorLine.Offset, TextEditor.SelectionAnchor - first));
-				} else {
-					TextEditor.SelectionAnchor = System.Math.Min (anchorLine.Offset + anchorLine.EditableLength, System.Math.Max (anchorLine.Offset, anchorLine.Offset + anchorColumn - last));
+				
+				if (TextEditor.Caret.Column != DocumentLocation.MinColumn) {
+					TextEditor.Caret.PreserveSelection = true;
+					TextEditor.Caret.Column = System.Math.Max (DocumentLocation.MinColumn, TextEditor.Caret.Column - last);
+					TextEditor.Caret.PreserveSelection = false;
 				}
-			}
-			
-			if (TextEditor.Caret.Column != DocumentLocation.MinColumn) {
-				TextEditor.Caret.PreserveSelection = true;
-				TextEditor.Caret.Column = System.Math.Max (DocumentLocation.MinColumn, TextEditor.Caret.Column - last);
-				TextEditor.Caret.PreserveSelection = false;
+				
+				if (TextEditor.IsSomethingSelected) 
+					TextEditor.ExtendSelectionTo (TextEditor.Caret.Offset);
 			}
-			
-			if (TextEditor.IsSomethingSelected) 
-				TextEditor.ExtendSelectionTo (TextEditor.Caret.Offset);
-		
-			Document.EndAtomicUndo ();
 			Document.CommitMultipleLineUpdate (startLineNr, endLineNr);
 		}
 		

@@ -70,13 +70,13 @@
 		{
 			IEditableTextBuffer buf = window.CompletionWidget as IEditableTextBuffer;
 			if (buf != null) {
-				buf.BeginAtomicUndo ();
-				buf.InsertText (buf.CursorPosition, element);
-				
-				// Move caret into the middle of the tags
-				buf.CursorPosition = window.CodeCompletionContext.TriggerOffset + cursorOffset;
-				buf.Select (buf.CursorPosition, buf.CursorPosition);
-				buf.EndAtomicUndo ();
+				using (var undo = buf.OpenUndoGroup ()) {
+					buf.InsertText (buf.CursorPosition, element);
+					
+					// Move caret into the middle of the tags
+					buf.CursorPosition = window.CodeCompletionContext.TriggerOffset + cursorOffset;
+					buf.Select (buf.CursorPosition, buf.CursorPosition);
+				}
 			}
 		}
 	}

@@ -186,10 +186,10 @@
 						if (newCaretOffset > seg.Offset) {
 							newCaretOffset += (indent.Length - oldIndent.Length);
 						}
-						Editor.Document.BeginAtomicUndo ();
-						Editor.Replace (seg.Offset, oldIndent.Length, indent);
-						Editor.Caret.Offset = newCaretOffset;
-						Editor.Document.EndAtomicUndo ();
+						using (var undo = Editor.OpenUndoGroup ()) {
+							Editor.Replace (seg.Offset, oldIndent.Length, indent);
+							Editor.Caret.Offset = newCaretOffset;
+						}
 					}
 				}
 				return ret;
@@ -245,19 +245,19 @@
 					string tag = String.Concat ("</", el.Name.FullName, ">");
 					if (XmlEditorOptions.AutoCompleteElements) {
 						
-						//make sure we have a clean atomic undo so the user can undo the tag insertion
-						//independently of the >
-						bool wasInAtomicUndo = this.Editor.Document.IsInAtomicUndo;
-						if (wasInAtomicUndo)
-							this.Editor.Document.EndAtomicUndo ();
+//						//make sure we have a clean atomic undo so the user can undo the tag insertion
+//						//independently of the >
+//						bool wasInAtomicUndo = this.Editor.Document.IsInAtomicUndo;
+//						if (wasInAtomicUndo)
+//							this.Editor.Document.EndAtomicUndo ();
 						
-						buf.BeginAtomicUndo ();
-						buf.InsertText (buf.CursorPosition, tag);
-						buf.CursorPosition -= tag.Length;
-						buf.EndAtomicUndo ();
+						using (var undo = buf.OpenUndoGroup ()) {
+							buf.InsertText (buf.CursorPosition, tag);
+							buf.CursorPosition -= tag.Length;
+						}
 						
-						if (wasInAtomicUndo)
-							this.Editor.Document.BeginAtomicUndo ();
+//						if (wasInAtomicUndo)
+//							this.Editor.Document.BeginAtomicUndo ();
 						
 						return null;
 					} else {
@@ -272,9 +272,7 @@
 			// Auto insert '>' when '/' is typed inside tag state (for quick tag closing)
 			//FIXME: avoid doing this when the next non-whitespace char is ">" or ignore the next ">" typed
 			if (XmlEditorOptions.AutoInsertFragments && tracker.Engine.CurrentState is XmlTagState && currentChar == '/') {
-				buf.BeginAtomicUndo ();
 				buf.InsertText (buf.CursorPosition, ">");
-				buf.EndAtomicUndo ();
 				return null;
 			}
 			

@@ -700,14 +700,14 @@
 		internal void FormatDocument ()
 		{
 			var formatter = CodeFormatterService.GetFormatter (TextXmlMimeType);
-			Editor.Document.BeginAtomicUndo ();
-			var loc = Editor.Caret.Location;
-			var text = formatter.FormatText (Document.Project != null ? Document.Project.Policies : null, Editor.Text);
-			if (text != null) {
-				Editor.Replace (0, Editor.Length, text);
-				Editor.Caret.Location = loc;
+			using (var undo = Editor.OpenUndoGroup ()) {
+				var loc = Editor.Caret.Location;
+				var text = formatter.FormatText (Document.Project != null ? Document.Project.Policies : null, Editor.Text);
+				if (text != null) {
+					Editor.Replace (0, Editor.Length, text);
+					Editor.Caret.Location = loc;
+				}
 			}
-			Editor.Document.EndAtomicUndo ();
 		}
 		
 		string GetFileContent (string fileName)

@@ -93,15 +93,10 @@
 		{
 			this.widget.Editor.Document.Redo ();
 		}
-
-		void IUndoHandler.BeginAtomicUndo ()
+		
+		IDisposable IUndoHandler.OpenUndoGroup ()
 		{
-			this.widget.Editor.Document.BeginAtomicUndo ();
-		}
-
-		void IUndoHandler.EndAtomicUndo ()
-		{
-			this.widget.Editor.Document.EndAtomicUndo ();
+			return this.widget.Editor.OpenUndoGroup ();
 		}
 
 		bool IUndoHandler.EnableUndo {

@@ -156,14 +156,9 @@
 			this.ComparisonWidget.OriginalEditor.Document.Redo ();
 		}
 
-		void IUndoHandler.BeginAtomicUndo ()
+		IDisposable IUndoHandler.OpenUndoGroup ()
 		{
-			this.ComparisonWidget.OriginalEditor.Document.BeginAtomicUndo ();
-		}
-
-		void IUndoHandler.EndAtomicUndo ()
-		{
-			this.ComparisonWidget.OriginalEditor.Document.EndAtomicUndo ();
+			return this.ComparisonWidget.OriginalEditor.OpenUndoGroup ();
 		}
 
 		bool IUndoHandler.EnableUndo {

@@ -658,23 +658,22 @@
 
 		protected virtual void UndoChange (TextEditor fromEditor, TextEditor toEditor, Hunk hunk)
 		{
-			toEditor.Document.BeginAtomicUndo ();
-			var start = toEditor.Document.GetLine (hunk.InsertStart);
-			int toOffset = start != null ? start.Offset : toEditor.Document.Length;
-			if (start != null && hunk.Inserted > 0) {
-				int line = Math.Min (hunk.InsertStart + hunk.Inserted - 1, toEditor.Document.LineCount);
-				var end = toEditor.Document.GetLine (line);
-				toEditor.Remove (start.Offset, end.EndOffset - start.Offset);
-			}
-
-			if (hunk.Removed > 0) {
-				start = fromEditor.Document.GetLine (Math.Min (hunk.RemoveStart, fromEditor.Document.LineCount));
-				int line = Math.Min (hunk.RemoveStart + hunk.Removed - 1, fromEditor.Document.LineCount);
-				var end = fromEditor.Document.GetLine (line);
-				toEditor.Insert (toOffset, start.Offset == end.EndOffset ? toEditor.EolMarker : fromEditor.Document.GetTextBetween (start.Offset, end.EndOffset));
+			using (var undo = toEditor.OpenUndoGroup ()) {
+				var start = toEditor.Document.GetLine (hunk.InsertStart);
+				int toOffset = start != null ? start.Offset : toEditor.Document.Length;
+				if (start != null && hunk.Inserted > 0) {
+					int line = Math.Min (hunk.InsertStart + hunk.Inserted - 1, toEditor.Document.LineCount);
+					var end = toEditor.Document.GetLine (line);
+					toEditor.Remove (start.Offset, end.EndOffset - start.Offset);
+				}
+	
+				if (hunk.Removed > 0) {
+					start = fromEditor.Document.GetLine (Math.Min (hunk.RemoveStart, fromEditor.Document.LineCount));
+					int line = Math.Min (hunk.RemoveStart + hunk.Removed - 1, fromEditor.Document.LineCount);
+					var end = fromEditor.Document.GetLine (line);
+					toEditor.Insert (toOffset, start.Offset == end.EndOffset ? toEditor.EolMarker : fromEditor.Document.GetTextBetween (start.Offset, end.EndOffset));
+				}
 			}
-
-			toEditor.Document.EndAtomicUndo ();
 		}
 
 		class MiddleArea : DrawingArea

@@ -826,7 +826,33 @@
 			}
 		}
 		
-		public void BeginAtomicUndo ()
+		class UndoGroup : IDisposable
+		{
+			Document doc;
+			
+			public UndoGroup (Document doc)
+			{
+				if (doc == null)
+					throw new ArgumentNullException ("doc");
+				this.doc = doc;
+				doc.BeginAtomicUndo ();
+			}
+			
+			public void Dispose ()
+			{
+				if (doc != null) {
+					doc.EndAtomicUndo ();
+					doc = null;
+				}
+			}
+		}
+		
+		public IDisposable OpenUndoGroup()
+		{
+			return new UndoGroup (this);
+		}
+		
+		internal void BeginAtomicUndo ()
 		{
 			if (atomicUndoLevel == 0) {
 				if (this.syntaxMode != null && !SuppressHighlightUpdate)
@@ -840,7 +866,7 @@
 			atomicUndoLevel++;
 		}
 		
-		public void EndAtomicUndo ()
+		internal void EndAtomicUndo ()
 		{
 			if (atomicUndoLevel <= 0)
 				throw new InvalidOperationException ("There is no atomic undo operation running.");

@@ -1865,6 +1865,11 @@
 		{
 			return Document.OffsetToLineNumber (offset);
 		}
+		
+		public IDisposable OpenUndoGroup()
+		{
+			return Document.OpenUndoGroup ();
+		}
 		#endregion
 		
 		#region Search & Replace

@@ -1064,6 +1064,11 @@
 		{
 			return Document.OffsetToLineNumber (offset);
 		}
+		
+		public IDisposable OpenUndoGroup()
+		{
+			return Document.OpenUndoGroup ();
+		}
 		#endregion
 		
 		#region Parent functions

@@ -59,15 +59,15 @@
 			var formatter = CodeFormatterService.GetFormatter (mt);
 			if (formatter == null)
 				return;
-			doc.Editor.Document.BeginAtomicUndo ();
-			var loc = doc.Editor.Caret.Location;
-			var text = formatter.FormatText (doc.Project != null ? doc.Project.Policies : null, doc.Editor.Text);
-			if (text != null) {
-				doc.Editor.Replace (0, doc.Editor.Length, text);
-				doc.Editor.Caret.Location = loc;
-				doc.Editor.Caret.CheckCaretPosition ();
+			using (var undo = doc.Editor.OpenUndoGroup ()) {
+				var loc = doc.Editor.Caret.Location;
+				var text = formatter.FormatText (doc.Project != null ? doc.Project.Policies : null, doc.Editor.Text);
+				if (text != null) {
+					doc.Editor.Replace (0, doc.Editor.Length, text);
+					doc.Editor.Caret.Location = loc;
+					doc.Editor.Caret.CheckCaretPosition ();
+				}
 			}
-			doc.Editor.Document.EndAtomicUndo ();
 		}
 	}
 	
@@ -97,18 +97,18 @@
 				return;
 			var selection = doc.Editor.SelectionRange;
 			
-			doc.Editor.Document.BeginAtomicUndo ();
-			if (formatter.SupportsOnTheFlyFormatting) {
-				formatter.OnTheFlyFormat (doc.Project != null ? doc.Project.Policies : null, doc.Editor, selection.Offset, selection.EndOffset);
-			} else {
-				var pol = doc.Project != null ? doc.Project.Policies : null;
-				string text = formatter.FormatText (pol, doc.Editor.Text, selection.Offset, selection.EndOffset);
-				if (text != null) {
-					doc.Editor.Replace (selection.Offset, selection.Length, text);
-					doc.Editor.SetSelection (selection.Offset, selection.Offset + text.Length - 1);
+			using (var undo = doc.Editor.OpenUndoGroup ()) {
+				if (formatter.SupportsOnTheFlyFormatting) {
+					formatter.OnTheFlyFormat (doc.Project != null ? doc.Project.Policies : null, doc.Editor, selection.Offset, selection.EndOffset);
+				} else {
+					var pol = doc.Project != null ? doc.Project.Policies : null;
+					string text = formatter.FormatText (pol, doc.Editor.Text, selection.Offset, selection.EndOffset);
+					if (text != null) {
+						doc.Editor.Replace (selection.Offset, selection.Length, text);
+						doc.Editor.SetSelection (selection.Offset, selection.Offset + text.Length - 1);
+					}
 				}
 			}
-			doc.Editor.Document.EndAtomicUndo ();
 		}
 	}
 }

@@ -110,7 +110,7 @@
 		StringBuilder buffer = null;
 		bool somethingReplaced;
 		bool utf8Failed;
-		
+		IDisposable undoGroup;
 		public void BeginReplace ()
 		{
 			somethingReplaced = false;
@@ -121,7 +121,7 @@
 			document = SearchDocument ();
 			if (document != null) {
 				Gtk.Application.Invoke (delegate {
-					document.Editor.Document.BeginAtomicUndo ();
+					undoGroup = document.Editor.OpenUndoGroup ();
 				});
 				return;
 			}
@@ -147,7 +147,12 @@
 		public void EndReplace ()
 		{
 			if (document != null) {
-				Gtk.Application.Invoke (delegate { document.Editor.Document.EndAtomicUndo (); document.Editor.Document.CommitUpdateAll (); });
+				Gtk.Application.Invoke (delegate { 
+					if (undoGroup != null) {
+						undoGroup.Dispose ();
+						undoGroup = null;
+					}
+					document.Editor.Document.CommitUpdateAll (); });
 				return;
 			}
 			if (buffer != null && somethingReplaced) {

@@ -41,7 +41,6 @@
 		void Undo ();
 		void Redo ();
 		
-		void BeginAtomicUndo ();
-		void EndAtomicUndo ();
+		IDisposable OpenUndoGroup ();
 	}
 }

@@ -175,11 +175,16 @@
 		{
 		}
 		
-		public void BeginAtomicUndo ()
+		class DisposeStub : IDisposable
 		{
+			public void Dispose ()
+			{
+			}
 		}
-		public void EndAtomicUndo ()
+		
+		public IDisposable OpenUndoGroup ()
 		{
+			return new DisposeStub ();
 		}
 		
 		public Mono.TextEditor.TextEditorData GetTextEditorData ()

@@ -244,21 +244,21 @@
 					buffer.CursorPosition = pos + 1;
 					return;
 				}
-				buffer.BeginAtomicUndo ();
-				buffer.DeleteText (pos, 1);
-				buffer.InsertText (pos, upper);
-				buffer.CursorPosition = pos + 1;
-				buffer.EndAtomicUndo ();
+				using (var undo = buffer.OpenUndoGroup ()) {
+					buffer.DeleteText (pos, 1);
+					buffer.InsertText (pos, upper);
+					buffer.CursorPosition = pos + 1;
+				}
 			} else {
 				string newText = selectedText.ToUpper ();
 				if (newText == selectedText)
 					return;
 				int startPos = buffer.SelectionStartPosition;
-				buffer.BeginAtomicUndo ();
-				buffer.DeleteText (startPos, selectedText.Length);
-				buffer.InsertText (startPos, newText);
-				buffer.Select (startPos, startPos + newText.Length);
-				buffer.EndAtomicUndo ();
+				using (var undo = buffer.OpenUndoGroup ()) {
+					buffer.DeleteText (startPos, selectedText.Length);
+					buffer.InsertText (startPos, newText);
+					buffer.Select (startPos, startPos + newText.Length);
+				}
 			}
 		}
 		
@@ -285,21 +285,21 @@
 					buffer.CursorPosition = pos + 1;
 					return;
 				};
-				buffer.BeginAtomicUndo ();
-				buffer.DeleteText (pos, 1);
-				buffer.InsertText (pos, lower);
-				buffer.CursorPosition = pos + 1;
-				buffer.EndAtomicUndo ();
+				using (var undo = buffer.OpenUndoGroup ()) {
+					buffer.DeleteText (pos, 1);
+					buffer.InsertText (pos, lower);
+					buffer.CursorPosition = pos + 1;
+				}
 			} else {
 				string newText = selectedText.ToLower ();
 				if (newText == selectedText)
 					return;
 				int startPos = buffer.SelectionStartPosition;
-				buffer.BeginAtomicUndo ();
-				buffer.DeleteText (startPos, selectedText.Length);
-				buffer.InsertText (startPos, newText);
-				buffer.Select (startPos, startPos + newText.Length);
-				buffer.EndAtomicUndo ();
+				using (var undo = buffer.OpenUndoGroup ()) {
+					buffer.DeleteText (startPos, selectedText.Length);
+					buffer.InsertText (startPos, newText);
+					buffer.Select (startPos, startPos + newText.Length);
+				}
 			}
 		}
 		
@@ -471,14 +471,13 @@
 				}
 				--pos;
 			}
-			
-			data.Document.BeginAtomicUndo ();
-			foreach (var info in removeList) {
-				((Mono.TextEditor.IBuffer)data.Document).Remove (info.Position, info.Length);
-				data.Document.CommitLineUpdate (data.Document.OffsetToLineNumber (info.Position));
+			using (var undo = data.OpenUndoGroup ()) {
+				foreach (var info in removeList) {
+					((Mono.TextEditor.IBuffer)data.Document).Remove (info.Position, info.Length);
+					data.Document.CommitLineUpdate (data.Document.OffsetToLineNumber (info.Position));
+				}
+				data.Caret.Offset = Math.Min (data.Caret.Offset, data.Document.Length - 1);
 			}
-			data.Caret.Offset = Math.Min (data.Caret.Offset, data.Document.Length - 1);
-			data.Document.EndAtomicUndo ();
 		}
 		
 		[CommandUpdateHandler (EditCommands.RemoveTrailingWhiteSpaces)]

@@ -180,12 +180,17 @@
 		{
 		}
 		
-		public void BeginAtomicUndo ()
+		class DisposeStub : IDisposable
+		{
+			public void Dispose ()
+			{
+			}
+		}
+		
+		public IDisposable OpenUndoGroup ()
 		{
-		}
-		public void EndAtomicUndo ()
-		{
-		}
+			return new DisposeStub ();
+		}
 		
 		public TextEditorData GetTextEditorData ()
 		{