Fixed AvalonEdit bugs.

git-svn-id: svn://svn.sharpdevelop.net/sharpdevelop/trunk@4670 1ccf3a8d-04fe-1044-b7c0-cef0b8235c61

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Document/TextDocument.cs

@@ -284,6 +284,8 @@ namespace ICSharpCode.AvalonEdit.Document
 		public void BeginUpdate()
 		{
 			VerifyAccess();
+			if (inDocumentChanging)
+				throw new InvalidOperationException("Cannot change document within another document change.");
 			beginUpdateCount++;
 			if (beginUpdateCount == 1) {
 				if (UpdateStarted != null)
@@ -474,10 +476,10 @@ namespace ICSharpCode.AvalonEdit.Document
 			if (offsetChangeMap != null)
 				offsetChangeMap.Freeze();
 			
+			// Ensure that all changes take place inside an update group.
+			// Will also take care of throwing an exception if inDocumentChanging is set.
 			BeginUpdate();
 			try {
-				if (inDocumentChanging)
-					throw new InvalidOperationException("Cannot change document within another document change.");
 				// protect document change against corruption by other changes inside the event handlers
 				inDocumentChanging = true;
 				try {

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Editing/Selection.cs

@@ -33,7 +33,7 @@ namespace ICSharpCode.AvalonEdit.Editing
 		
 		/// <summary>
 		/// Gets the smallest segment that contains all segments in this selection.
-		/// Returns null if the selection is empty.
+		/// May return null if the selection is empty.
 		/// </summary>
 		public abstract ISegment SurroundingSegment { get; }
 		

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/TextEditor.cs

@@ -511,7 +511,7 @@ namespace ICSharpCode.AvalonEdit
 		/// </summary>
 		public void SelectAll()
 		{
-			ApplicationCommands.SelectAll.Execute(null, TextArea);
+			Execute(ApplicationCommands.SelectAll);
 		}
 		
 		/// <summary>
@@ -666,7 +666,7 @@ namespace ICSharpCode.AvalonEdit
 		public int SelectionLength {
 			get {
 				TextArea textArea = this.TextArea;
-				if (textArea != null)
+				if (textArea != null && !textArea.Selection.IsEmpty)
 					return textArea.Selection.SurroundingSegment.Length;
 				else
 					return 0;