diff --git a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/DocumentChangeEventArgs.cs b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/DocumentChangeEventArgs.cs
index 431d6ab4db..02cbe5ac71 100644
--- a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/DocumentChangeEventArgs.cs
+++ b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/DocumentChangeEventArgs.cs
@@ -71,14 +71,24 @@ namespace ICSharpCode.AvalonEdit.Document
 		public DocumentChangeEventArgs(int offset, string removedText, string insertedText, OffsetChangeMap offsetChangeMap)
 			: base(offset, removedText, insertedText)
 		{
-			ThrowUtil.CheckNotNegative(offset, "offset");
-			ThrowUtil.CheckNotNull(removedText, "removedText");
-			ThrowUtil.CheckNotNull(insertedText, "insertedText");
-			
+			SetOffsetChangeMap(offsetChangeMap);
+		}
+		
+		/// <summary>
+		/// Creates a new DocumentChangeEventArgs object.
+		/// </summary>
+		public DocumentChangeEventArgs(int offset, ITextSource removedText, ITextSource insertedText, OffsetChangeMap offsetChangeMap)
+			: base(offset, removedText, insertedText)
+		{
+			SetOffsetChangeMap(offsetChangeMap);
+		}
+		
+		void SetOffsetChangeMap(OffsetChangeMap offsetChangeMap)
+		{
 			if (offsetChangeMap != null) {
 				if (!offsetChangeMap.IsFrozen)
 					throw new ArgumentException("The OffsetChangeMap must be frozen before it can be used in DocumentChangeEventArgs");
-				if (!offsetChangeMap.IsValidForDocumentChange(offset, removedText.Length, insertedText.Length))
+				if (!offsetChangeMap.IsValidForDocumentChange(this.Offset, this.RemovalLength, this.InsertionLength))
 					throw new ArgumentException("OffsetChangeMap is not valid for this document change", "offsetChangeMap");
 				this.offsetChangeMap = offsetChangeMap;
 			}
diff --git a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/LineManager.cs b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/LineManager.cs
index 0325fef44b..3f05979544 100644
--- a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/LineManager.cs
+++ b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/LineManager.cs
@@ -6,6 +6,7 @@ using System;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
+using ICSharpCode.NRefactory.Editor;
 
 namespace ICSharpCode.AvalonEdit.Document
 {
@@ -181,7 +182,7 @@ namespace ICSharpCode.AvalonEdit.Document
 		#endregion
 		
 		#region Insert
-		public void Insert(int offset, string text)
+		public void Insert(int offset, ITextSource text)
 		{
 			DocumentLine line = documentLineTree.GetByOffset(offset);
 			int lineOffset = line.Offset;
@@ -202,7 +203,7 @@ namespace ICSharpCode.AvalonEdit.Document
 			if (ds == SimpleSegment.Invalid) {
 				// no newline is being inserted, all text is inserted in a single line
 				//line.InsertedLinePart(offset - line.Offset, text.Length);
-				SetLineLength(line, line.TotalLength + text.Length);
+				SetLineLength(line, line.TotalLength + text.TextLength);
 				return;
 			}
 			//DocumentLine firstLine = line;
@@ -224,9 +225,9 @@ namespace ICSharpCode.AvalonEdit.Document
 			}
 			//firstLine.SplitTo(line);
 			// insert rest after last delimiter
-			if (lastDelimiterEnd != text.Length) {
+			if (lastDelimiterEnd != text.TextLength) {
 				//line.InsertedLinePart(0, text.Length - lastDelimiterEnd);
-				SetLineLength(line, line.TotalLength + text.Length - lastDelimiterEnd);
+				SetLineLength(line, line.TotalLength + text.TextLength - lastDelimiterEnd);
 			}
 		}
 		
diff --git a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/RopeTextSource.cs b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/RopeTextSource.cs
index fdc1935066..a33e1cf19d 100644
--- a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/RopeTextSource.cs
+++ b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/RopeTextSource.cs
@@ -11,6 +11,7 @@ namespace ICSharpCode.AvalonEdit.Document
 	/// <summary>
 	/// Implements the ITextSource interface using a rope.
 	/// </summary>
+	[Serializable]
 	public sealed class RopeTextSource : ITextSource
 	{
 		readonly Rope<char> rope;
diff --git a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/TextDocument.cs b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/TextDocument.cs
index d2e41154a6..454124df12 100644
--- a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/TextDocument.cs
+++ b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/TextDocument.cs
@@ -524,6 +524,21 @@ namespace ICSharpCode.AvalonEdit.Document
 		/// The caret will also move behind the inserted text.
 		/// </remarks>
 		public void Insert(int offset, string text)
+		{
+			Replace(offset, 0, new StringTextSource(text), null);
+		}
+		
+		/// <summary>
+		/// Inserts text.
+		/// </summary>
+		/// <param name="offset">The offset at which the text is inserted.</param>
+		/// <param name="text">The new text.</param>
+		/// <remarks>
+		/// Anchors positioned exactly at the insertion offset will move according to their movement type.
+		/// For AnchorMovementType.Default, they will move behind the inserted text.
+		/// The caret will also move behind the inserted text.
+		/// </remarks>
+		public void Insert(int offset, ITextSource text)
 		{
 			Replace(offset, 0, text, null);
 		}
@@ -539,6 +554,25 @@ namespace ICSharpCode.AvalonEdit.Document
 		/// The caret will also move according to the <paramref name="defaultAnchorMovementType"/> parameter.
 		/// </param>
 		public void Insert(int offset, string text, AnchorMovementType defaultAnchorMovementType)
+		{
+			if (defaultAnchorMovementType == AnchorMovementType.BeforeInsertion) {
+				Replace(offset, 0, new StringTextSource(text), OffsetChangeMappingType.KeepAnchorBeforeInsertion);
+			} else {
+				Replace(offset, 0, new StringTextSource(text), null);
+			}
+		}
+		
+		/// <summary>
+		/// Inserts text.
+		/// </summary>
+		/// <param name="offset">The offset at which the text is inserted.</param>
+		/// <param name="text">The new text.</param>
+		/// <param name="defaultAnchorMovementType">
+		/// Anchors positioned exactly at the insertion offset will move according to the anchor's movement type.
+		/// For AnchorMovementType.Default, they will move according to the movement type specified by this parameter.
+		/// The caret will also move according to the <paramref name="defaultAnchorMovementType"/> parameter.
+		/// </param>
+		public void Insert(int offset, ITextSource text, AnchorMovementType defaultAnchorMovementType)
 		{
 			if (defaultAnchorMovementType == AnchorMovementType.BeforeInsertion) {
 				Replace(offset, 0, text, OffsetChangeMappingType.KeepAnchorBeforeInsertion);
@@ -562,7 +596,7 @@ namespace ICSharpCode.AvalonEdit.Document
 		/// <param name="length">Length of the text to be removed.</param>
 		public void Remove(int offset, int length)
 		{
-			Replace(offset, length, string.Empty);
+			Replace(offset, length, StringTextSource.Empty);
 		}
 		
 		internal bool inDocumentChanging;
@@ -571,6 +605,16 @@ namespace ICSharpCode.AvalonEdit.Document
 		/// Replaces text.
 		/// </summary>
 		public void Replace(ISegment segment, string text)
+		{
+			if (segment == null)
+				throw new ArgumentNullException("segment");
+			Replace(segment.Offset, segment.Length, new StringTextSource(text), null);
+		}
+		
+		/// <summary>
+		/// Replaces text.
+		/// </summary>
+		public void Replace(ISegment segment, ITextSource text)
 		{
 			if (segment == null)
 				throw new ArgumentNullException("segment");
@@ -584,6 +628,17 @@ namespace ICSharpCode.AvalonEdit.Document
 		/// <param name="length">The length of the text to be replaced.</param>
 		/// <param name="text">The new text.</param>
 		public void Replace(int offset, int length, string text)
+		{
+			Replace(offset, length, new StringTextSource(text), null);
+		}
+		
+		/// <summary>
+		/// Replaces text.
+		/// </summary>
+		/// <param name="offset">The starting offset of the text to be replaced.</param>
+		/// <param name="length">The length of the text to be replaced.</param>
+		/// <param name="text">The new text.</param>
+		public void Replace(int offset, int length, ITextSource text)
 		{
 			Replace(offset, length, text, null);
 		}
@@ -597,6 +652,19 @@ namespace ICSharpCode.AvalonEdit.Document
 		/// <param name="offsetChangeMappingType">The offsetChangeMappingType determines how offsets inside the old text are mapped to the new text.
 		/// This affects how the anchors and segments inside the replaced region behave.</param>
 		public void Replace(int offset, int length, string text, OffsetChangeMappingType offsetChangeMappingType)
+		{
+			Replace(offset, length, new StringTextSource(text), offsetChangeMappingType);
+		}
+		
+		/// <summary>
+		/// Replaces text.
+		/// </summary>
+		/// <param name="offset">The starting offset of the text to be replaced.</param>
+		/// <param name="length">The length of the text to be replaced.</param>
+		/// <param name="text">The new text.</param>
+		/// <param name="offsetChangeMappingType">The offsetChangeMappingType determines how offsets inside the old text are mapped to the new text.
+		/// This affects how the anchors and segments inside the replaced region behave.</param>
+		public void Replace(int offset, int length, ITextSource text, OffsetChangeMappingType offsetChangeMappingType)
 		{
 			if (text == null)
 				throw new ArgumentNullException("text");
@@ -607,33 +675,33 @@ namespace ICSharpCode.AvalonEdit.Document
 					break;
 				case OffsetChangeMappingType.KeepAnchorBeforeInsertion:
 					Replace(offset, length, text, OffsetChangeMap.FromSingleElement(
-						new OffsetChangeMapEntry(offset, length, text.Length, false, true)));
+						new OffsetChangeMapEntry(offset, length, text.TextLength, false, true)));
 					break;
 				case OffsetChangeMappingType.RemoveAndInsert:
-					if (length == 0 || text.Length == 0) {
+					if (length == 0 || text.TextLength == 0) {
 						// only insertion or only removal?
 						// OffsetChangeMappingType doesn't matter, just use Normal.
 						Replace(offset, length, text, null);
 					} else {
 						OffsetChangeMap map = new OffsetChangeMap(2);
 						map.Add(new OffsetChangeMapEntry(offset, length, 0));
-						map.Add(new OffsetChangeMapEntry(offset, 0, text.Length));
+						map.Add(new OffsetChangeMapEntry(offset, 0, text.TextLength));
 						map.Freeze();
 						Replace(offset, length, text, map);
 					}
 					break;
 				case OffsetChangeMappingType.CharacterReplace:
-					if (length == 0 || text.Length == 0) {
+					if (length == 0 || text.TextLength == 0) {
 						// only insertion or only removal?
 						// OffsetChangeMappingType doesn't matter, just use Normal.
 						Replace(offset, length, text, null);
-					} else if (text.Length > length) {
+					} else if (text.TextLength > length) {
 						// look at OffsetChangeMappingType.CharacterReplace XML comments on why we need to replace
 						// the last character
-						OffsetChangeMapEntry entry = new OffsetChangeMapEntry(offset + length - 1, 1, 1 + text.Length - length);
+						OffsetChangeMapEntry entry = new OffsetChangeMapEntry(offset + length - 1, 1, 1 + text.TextLength - length);
 						Replace(offset, length, text, OffsetChangeMap.FromSingleElement(entry));
-					} else if (text.Length < length) {
-						OffsetChangeMapEntry entry = new OffsetChangeMapEntry(offset + text.Length, length - text.Length, 0, true, false);
+					} else if (text.TextLength < length) {
+						OffsetChangeMapEntry entry = new OffsetChangeMapEntry(offset + text.TextLength, length - text.TextLength, 0, true, false);
 						Replace(offset, length, text, OffsetChangeMap.FromSingleElement(entry));
 					} else {
 						Replace(offset, length, text, OffsetChangeMap.Empty);
@@ -660,10 +728,30 @@ namespace ICSharpCode.AvalonEdit.Document
 		/// DocumentChangeEventArgs instance.
 		/// </param>
 		public void Replace(int offset, int length, string text, OffsetChangeMap offsetChangeMap)
+		{
+			Replace(offset, length, new StringTextSource(text), offsetChangeMap);
+		}
+		
+		/// <summary>
+		/// Replaces text.
+		/// </summary>
+		/// <param name="offset">The starting offset of the text to be replaced.</param>
+		/// <param name="length">The length of the text to be replaced.</param>
+		/// <param name="text">The new text.</param>
+		/// <param name="offsetChangeMap">The offsetChangeMap determines how offsets inside the old text are mapped to the new text.
+		/// This affects how the anchors and segments inside the replaced region behave.
+		/// If you pass null (the default when using one of the other overloads), the offsets are changed as
+		/// in OffsetChangeMappingType.Normal mode.
+		/// If you pass OffsetChangeMap.Empty, then everything will stay in its old place (OffsetChangeMappingType.CharacterReplace mode).
+		/// The offsetChangeMap must be a valid 'explanation' for the document change. See <see cref="OffsetChangeMap.IsValidForDocumentChange"/>.
+		/// Passing an OffsetChangeMap to the Replace method will automatically freeze it to ensure the thread safety of the resulting
+		/// DocumentChangeEventArgs instance.
+		/// </param>
+		public void Replace(int offset, int length, ITextSource text, OffsetChangeMap offsetChangeMap)
 		{
 			if (text == null)
 				throw new ArgumentNullException("text");
-			
+			text = text.CreateSnapshot();
 			if (offsetChangeMap != null)
 				offsetChangeMap.Freeze();
 			
@@ -687,18 +775,26 @@ namespace ICSharpCode.AvalonEdit.Document
 			}
 		}
 		
-		void DoReplace(int offset, int length, string newText, OffsetChangeMap offsetChangeMap)
+		void DoReplace(int offset, int length, ITextSource newText, OffsetChangeMap offsetChangeMap)
 		{
-			if (length == 0 && newText.Length == 0)
+			if (length == 0 && newText.TextLength == 0)
 				return;
 			
 			// trying to replace a single character in 'Normal' mode?
 			// for single characters, 'CharacterReplace' mode is equivalent, but more performant
 			// (we don't have to touch the anchorTree at all in 'CharacterReplace' mode)
-			if (length == 1 && newText.Length == 1 && offsetChangeMap == null)
+			if (length == 1 && newText.TextLength == 1 && offsetChangeMap == null)
 				offsetChangeMap = OffsetChangeMap.Empty;
 			
-			string removedText = rope.ToString(offset, length);
+			ITextSource removedText;
+			if (length == 0) {
+				removedText = StringTextSource.Empty;
+			} else if (length < 100) {
+				removedText = new StringTextSource(rope.ToString(offset, length));
+			} else {
+				// use a rope if the removed string is long
+				removedText = new RopeTextSource(rope.GetRange(offset, length));
+			}
 			DocumentChangeEventArgs args = new DocumentChangeEventArgs(offset, removedText, newText, offsetChangeMap);
 			
 			// fire DocumentChanging event
@@ -721,7 +817,11 @@ namespace ICSharpCode.AvalonEdit.Document
 				if (offset == 0 && length == rope.Length) {
 					// optimize replacing the whole document
 					rope.Clear();
-					rope.InsertText(0, newText);
+					var newRopeTextSource = newText as RopeTextSource;
+					if (newRopeTextSource != null)
+						rope.InsertRange(0, newRopeTextSource.GetRope());
+					else
+						rope.InsertText(0, newText.Text);
 					lineManager.Rebuild();
 				} else {
 					rope.RemoveRange(offset, length);
@@ -729,7 +829,11 @@ namespace ICSharpCode.AvalonEdit.Document
 					#if DEBUG
 					lineTree.CheckProperties();
 					#endif
-					rope.InsertText(offset, newText);
+					var newRopeTextSource = newText as RopeTextSource;
+					if (newRopeTextSource != null)
+						rope.InsertRange(offset, newRopeTextSource.GetRope());
+					else
+						rope.InsertText(offset, newText.Text);
 					lineManager.Insert(offset, newText);
 					#if DEBUG
 					lineTree.CheckProperties();
diff --git a/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/IDocument.cs b/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/IDocument.cs
index 4201ce4484..f9a793b911 100644
--- a/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/IDocument.cs
+++ b/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/IDocument.cs
@@ -109,6 +109,18 @@ namespace ICSharpCode.NRefactory.Editor
 		/// </remarks>
 		void Insert(int offset, string text);
 		
+		/// <summary>
+		/// Inserts text.
+		/// </summary>
+		/// <param name="offset">The offset at which the text is inserted.</param>
+		/// <param name="text">The new text.</param>
+		/// <remarks>
+		/// Anchors positioned exactly at the insertion offset will move according to their movement type.
+		/// For AnchorMovementType.Default, they will move behind the inserted text.
+		/// The caret will also move behind the inserted text.
+		/// </remarks>
+		void Insert(int offset, ITextSource text);
+		
 		/// <summary>
 		/// Inserts text.
 		/// </summary>
@@ -121,6 +133,18 @@ namespace ICSharpCode.NRefactory.Editor
 		/// </param>
 		void Insert(int offset, string text, AnchorMovementType defaultAnchorMovementType);
 		
+		/// <summary>
+		/// Inserts text.
+		/// </summary>
+		/// <param name="offset">The offset at which the text is inserted.</param>
+		/// <param name="text">The new text.</param>
+		/// <param name="defaultAnchorMovementType">
+		/// Anchors positioned exactly at the insertion offset will move according to the anchor's movement type.
+		/// For AnchorMovementType.Default, they will move according to the movement type specified by this parameter.
+		/// The caret will also move according to the <paramref name="defaultAnchorMovementType"/> parameter.
+		/// </param>
+		void Insert(int offset, ITextSource text, AnchorMovementType defaultAnchorMovementType);
+		
 		/// <summary>
 		/// Removes text.
 		/// </summary>
@@ -136,6 +160,14 @@ namespace ICSharpCode.NRefactory.Editor
 		/// <param name="newText">The new text.</param>
 		void Replace(int offset, int length, string newText);
 		
+		/// <summary>
+		/// Replaces text.
+		/// </summary>
+		/// <param name="offset">The starting offset of the text to be replaced.</param>
+		/// <param name="length">The length of the text to be replaced.</param>
+		/// <param name="newText">The new text.</param>
+		void Replace(int offset, int length, ITextSource newText);
+		
 		/// <summary>
 		/// Make the document combine the following actions into a single
 		/// action for undo purposes.
diff --git a/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/ReadOnlyDocument.cs b/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/ReadOnlyDocument.cs
index a4d76a8394..2a36ccda33 100644
--- a/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/ReadOnlyDocument.cs
+++ b/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/ReadOnlyDocument.cs
@@ -257,6 +257,21 @@ namespace ICSharpCode.NRefactory.Editor
 			throw new NotSupportedException();
 		}
 		
+		void IDocument.Insert(int offset, ITextSource text)
+		{
+			throw new NotImplementedException();
+		}
+		
+		void IDocument.Insert(int offset, ITextSource text, AnchorMovementType defaultAnchorMovementType)
+		{
+			throw new NotImplementedException();
+		}
+		
+		void IDocument.Replace(int offset, int length, ITextSource newText)
+		{
+			throw new NotImplementedException();
+		}
+		
 		void IDocument.StartUndoableAction()
 		{
 		}
diff --git a/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/StringBuilderDocument.cs b/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/StringBuilderDocument.cs
index 79553a4136..fad9dfcc5b 100644
--- a/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/StringBuilderDocument.cs
+++ b/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/StringBuilderDocument.cs
@@ -104,17 +104,35 @@ namespace ICSharpCode.NRefactory.Editor
 			Replace(offset, 0, text);
 		}
 		
+		/// <inheritdoc/>
+		public void Insert(int offset, ITextSource text)
+		{
+			if (text == null)
+				throw new ArgumentNullException("text");
+			Replace(offset, 0, text.Text);
+		}
+		
 		/// <inheritdoc/>
 		public void Insert(int offset, string text, AnchorMovementType defaultAnchorMovementType)
 		{
 			if (offset < 0 || offset > this.TextLength)
 				throw new ArgumentOutOfRangeException("offset");
+			if (text == null)
+				throw new ArgumentNullException("text");
 			if (defaultAnchorMovementType == AnchorMovementType.BeforeInsertion)
 				PerformChange(new InsertionWithMovementBefore(offset, text));
 			else
 				Replace(offset, 0, text);
 		}
 		
+		/// <inheritdoc/>
+		public void Insert(int offset, ITextSource text, AnchorMovementType defaultAnchorMovementType)
+		{
+			if (text == null)
+				throw new ArgumentNullException("text");
+			Insert(offset, text.Text, defaultAnchorMovementType);
+		}
+		
 		[Serializable]
 		sealed class InsertionWithMovementBefore : TextChangeEventArgs
 		{
@@ -149,6 +167,14 @@ namespace ICSharpCode.NRefactory.Editor
 			PerformChange(new TextChangeEventArgs(offset, b.ToString(offset, length), newText));
 		}
 		
+		/// <inheritdoc/>
+		public void Replace(int offset, int length, ITextSource newText)
+		{
+			if (newText == null)
+				throw new ArgumentNullException("newText");
+			Replace(offset, length, newText.Text);
+		}
+		
 		bool isInChange;
 		
 		void PerformChange(TextChangeEventArgs change)
diff --git a/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/StringTextSource.cs b/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/StringTextSource.cs
index 3a24db3646..36780954bd 100644
--- a/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/StringTextSource.cs
+++ b/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/StringTextSource.cs
@@ -27,6 +27,11 @@ namespace ICSharpCode.NRefactory.Editor
 	[Serializable]
 	public class StringTextSource : ITextSource
 	{
+		/// <summary>
+		/// Gets a text source containing the empty string.
+		/// </summary>
+		public static readonly StringTextSource Empty = new StringTextSource(string.Empty);
+		
 		readonly string text;
 		readonly ITextSourceVersion version;
 		
@@ -69,7 +74,7 @@ namespace ICSharpCode.NRefactory.Editor
 		/// <inheritdoc/>
 		public ITextSource CreateSnapshot()
 		{
-			return this; // StringTextBuffer is immutable
+			return this; // StringTextSource is immutable
 		}
 		
 		/// <inheritdoc/>
diff --git a/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/TextChangeEventArgs.cs b/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/TextChangeEventArgs.cs
index 936de37aa4..f1eeb4d27f 100644
--- a/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/TextChangeEventArgs.cs
+++ b/src/Libraries/NRefactory/ICSharpCode.NRefactory/Editor/TextChangeEventArgs.cs
@@ -28,8 +28,8 @@ namespace ICSharpCode.NRefactory.Editor
 	public class TextChangeEventArgs : EventArgs
 	{
 		readonly int offset;
-		readonly string removedText;
-		readonly string insertedText;
+		readonly ITextSource removedText;
+		readonly ITextSource insertedText;
 		
 		/// <summary>
 		/// The offset at which the change occurs.
@@ -41,7 +41,7 @@ namespace ICSharpCode.NRefactory.Editor
 		/// <summary>
 		/// The text that was removed.
 		/// </summary>
-		public string RemovedText {
+		public ITextSource RemovedText {
 			get { return removedText; }
 		}
 		
@@ -49,13 +49,13 @@ namespace ICSharpCode.NRefactory.Editor
 		/// The number of characters removed.
 		/// </summary>
 		public int RemovalLength {
-			get { return removedText.Length; }
+			get { return removedText.TextLength; }
 		}
 		
 		/// <summary>
 		/// The text that was inserted.
 		/// </summary>
-		public string InsertedText {
+		public ITextSource InsertedText {
 			get { return insertedText; }
 		}
 		
@@ -63,7 +63,7 @@ namespace ICSharpCode.NRefactory.Editor
 		/// The number of characters inserted.
 		/// </summary>
 		public int InsertionLength {
-			get { return insertedText.Length; }
+			get { return insertedText.TextLength; }
 		}
 		
 		/// <summary>
@@ -71,9 +71,23 @@ namespace ICSharpCode.NRefactory.Editor
 		/// </summary>
 		public TextChangeEventArgs(int offset, string removedText, string insertedText)
 		{
+			if (offset < 0)
+				throw new ArgumentOutOfRangeException("offset", offset, "offset must not be negative");
 			this.offset = offset;
-			this.removedText = removedText ?? string.Empty;
-			this.insertedText = insertedText ?? string.Empty;
+			this.removedText = removedText != null ? new StringTextSource(removedText) : StringTextSource.Empty;
+			this.insertedText = insertedText != null ? new StringTextSource(insertedText) : StringTextSource.Empty;
+		}
+		
+		/// <summary>
+		/// Creates a new TextChangeEventArgs object.
+		/// </summary>
+		public TextChangeEventArgs(int offset, ITextSource removedText, ITextSource insertedText)
+		{
+			if (offset < 0)
+				throw new ArgumentOutOfRangeException("offset", offset, "offset must not be negative");
+			this.offset = offset;
+			this.removedText = removedText ?? StringTextSource.Empty;
+			this.insertedText = insertedText ?? StringTextSource.Empty;
 		}
 		
 		/// <summary>