diff --git a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Gui/TextArea.cs b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Gui/TextArea.cs
index 5a35d7827a..56f2fee901 100644
--- a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Gui/TextArea.cs
+++ b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Gui/TextArea.cs
@@ -632,6 +632,8 @@ namespace ICSharpCode.AvalonEdit
 		
 		internal void RemoveSelectedText()
 		{
+			if (this.Document == null)
+				throw ThrowUtil.NoDocumentAssigned();
 			selection.RemoveSelectedText(this);
 			#if DEBUG
 			if (!selection.IsEmpty) {
@@ -646,11 +648,13 @@ namespace ICSharpCode.AvalonEdit
 		{
 			if (newText == null)
 				throw new ArgumentNullException("newText");
-			using (Document.RunUpdate()) {
+			if (this.Document == null)
+				throw ThrowUtil.NoDocumentAssigned();
+			using (this.Document.RunUpdate()) {
 				RemoveSelectedText();
 				if (newText.Length > 0) {
 					if (ReadOnlySectionProvider.CanInsert(Caret.Offset)) {
-						Document.Insert(Caret.Offset, newText);
+						this.Document.Insert(Caret.Offset, newText);
 					}
 				}
 			}
diff --git a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Gui/TextEditor.cs b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Gui/TextEditor.cs
index 9776a1e577..0e9b8aefd0 100644
--- a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Gui/TextEditor.cs
+++ b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Gui/TextEditor.cs
@@ -43,7 +43,9 @@ namespace ICSharpCode.AvalonEdit
 		/// <summary>
 		/// Creates a new TextEditor instance.
 		/// </summary>
-		public TextEditor() : this(new TextArea()) {}
+		public TextEditor() : this(new TextArea())
+		{
+		}
 		
 		// Forward focus to TextArea.
 		/// <inheritdoc/>
@@ -65,6 +67,7 @@ namespace ICSharpCode.AvalonEdit
 				throw new ArgumentNullException("textArea");
 			this.textArea = textArea;
 			this.Options = textArea.Options;
+			this.Document = new TextDocument();
 			textArea.SetBinding(TextArea.DocumentProperty, new Binding("Document") { Source = this });
 			textArea.SetBinding(TextArea.OptionsProperty, new Binding("Options") { Source = this });
 		}
@@ -184,7 +187,7 @@ namespace ICSharpCode.AvalonEdit
 			set {
 				if (value == null)
 					value = string.Empty;
-				TextDocument document = GetOrCreateDocument();
+				TextDocument document = GetDocument();
 				document.Text = value;
 				// after replacing the full text, the caret is positioned at the end of the document
 				// - reset it to the beginning.
@@ -193,13 +196,11 @@ namespace ICSharpCode.AvalonEdit
 			}
 		}
 		
-		TextDocument GetOrCreateDocument()
+		TextDocument GetDocument()
 		{
 			TextDocument document = this.Document;
-			if (document == null) {
-				document = new TextDocument();
-				this.Document = document;
-			}
+			if (document == null)
+				throw ThrowUtil.NoDocumentAssigned();
 			return document;
 		}
 		
@@ -300,7 +301,7 @@ namespace ICSharpCode.AvalonEdit
 		/// </summary>
 		public void AppendText(string textData)
 		{
-			TextDocument document = GetOrCreateDocument();
+			var document = GetDocument();
 			document.Insert(document.TextLength, textData);
 		}
 		
@@ -309,7 +310,7 @@ namespace ICSharpCode.AvalonEdit
 		/// </summary>
 		public void BeginChange()
 		{
-			GetOrCreateDocument().BeginUpdate();
+			GetDocument().BeginUpdate();
 		}
 		
 		/// <summary>
@@ -334,7 +335,7 @@ namespace ICSharpCode.AvalonEdit
 		/// </summary>
 		public IDisposable DeclareChangeBlock()
 		{
-			return GetOrCreateDocument().RunUpdate();
+			return GetDocument().RunUpdate();
 		}
 		
 		/// <summary>
@@ -342,7 +343,7 @@ namespace ICSharpCode.AvalonEdit
 		/// </summary>
 		public void EndChange()
 		{
-			GetOrCreateDocument().EndUpdate();
+			GetDocument().EndUpdate();
 		}
 		
 		/// <summary>
diff --git a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Gui/TextView.cs b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Gui/TextView.cs
index 5872d99201..1c10715287 100644
--- a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Gui/TextView.cs
+++ b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Gui/TextView.cs
@@ -562,28 +562,34 @@ namespace ICSharpCode.AvalonEdit.Gui
 			InvalidateVisual(); // = InvalidateArrange+InvalidateRender
 			textLayer.InvalidateVisual();
 			
-			if (document == null)
-				return Size.Empty;
-			
 			double maxWidth;
-			inMeasure = true;
-			try {
-				maxWidth = CreateAndMeasureVisualLines(availableSize);
-			} finally {
-				inMeasure = false;
+			if (document == null) {
+				// no document -> create empty list of lines
+				allVisualLines = new List<VisualLine>();
+				visibleVisualLines = allVisualLines.AsReadOnly();
+				maxWidth = 0;
+			} else {
+				inMeasure = true;
+				try {
+					maxWidth = CreateAndMeasureVisualLines(availableSize);
+				} finally {
+					inMeasure = false;
+				}
 			}
 			
 			textLayer.RemoveInlineObjectsNow();
 			
+			double heightTreeHeight = this.DocumentHeight;
+			
 			SetScrollData(availableSize,
-			              new Size(maxWidth, heightTree.TotalHeight),
+			              new Size(maxWidth, heightTreeHeight),
 			              scrollOffset);
 			if (VisualLinesChanged != null)
 				VisualLinesChanged(this, EventArgs.Empty);
 			
 			return new Size(
 				canHorizontallyScroll ? Math.Min(availableSize.Width, maxWidth) : maxWidth,
-				canVerticallyScroll ? Math.Min(availableSize.Height, heightTree.TotalHeight) : heightTree.TotalHeight
+				canVerticallyScroll ? Math.Min(availableSize.Height, heightTreeHeight) : heightTreeHeight
 			);
 		}
 		
@@ -734,6 +740,10 @@ namespace ICSharpCode.AvalonEdit.Gui
 		/// </summary>
 		protected override Size ArrangeOverride(Size finalSize)
 		{
+			foreach (UIElement layer in layers) {
+				layer.Arrange(new Rect(new Point(0, 0), finalSize));
+			}
+			
 			if (document == null || allVisualLines.Count == 0)
 				return finalSize;
 			
@@ -752,10 +762,6 @@ namespace ICSharpCode.AvalonEdit.Gui
 			
 //			double maxWidth = 0;
 			
-			foreach (UIElement adorner in layers) {
-				adorner.Arrange(new Rect(new Point(0, 0), finalSize));
-			}
-			
 			if (visibleVisualLines != null) {
 				Point pos = new Point(-scrollOffset.X, -clippedPixelsOnTop);
 				foreach (VisualLine visualLine in visibleVisualLines) {
@@ -1222,7 +1228,7 @@ namespace ICSharpCode.AvalonEdit.Gui
 		{
 			VerifyAccess();
 			if (this.Document == null)
-				throw new InvalidOperationException("There is no document assigned to the TextView");
+				throw ThrowUtil.NoDocumentAssigned();
 			DocumentLine documentLine = this.Document.GetLineByNumber(position.Line);
 			VisualLine visualLine = GetOrConstructVisualLine(documentLine);
 			int visualColumn = position.VisualColumn;
@@ -1243,7 +1249,7 @@ namespace ICSharpCode.AvalonEdit.Gui
 		{
 			VerifyAccess();
 			if (this.Document == null)
-				throw new InvalidOperationException("There is no document assigned to the TextView");
+				throw ThrowUtil.NoDocumentAssigned();
 			VisualLine line = GetVisualLineFromVisualTop(visualPosition.Y);
 			if (line == null)
 				return null;
@@ -1425,6 +1431,8 @@ namespace ICSharpCode.AvalonEdit.Gui
 		public CollapsedLineSection CollapseLines(DocumentLine start, DocumentLine end)
 		{
 			VerifyAccess();
+			if (heightTree == null)
+				throw ThrowUtil.NoDocumentAssigned();
 			return heightTree.CollapseText(start, end);
 		}
 		
@@ -1432,7 +1440,10 @@ namespace ICSharpCode.AvalonEdit.Gui
 		/// Gets the height of the document.
 		/// </summary>
 		public double DocumentHeight {
-			get { return heightTree.TotalHeight; }
+			get {
+				// return 0 if there is no document = no heightTree
+				return heightTree != null ? heightTree.TotalHeight : 0;
+			}
 		}
 		
 		/// <summary>
@@ -1442,7 +1453,7 @@ namespace ICSharpCode.AvalonEdit.Gui
 		{
 			VerifyAccess();
 			if (heightTree == null)
-				throw new InvalidOperationException();
+				throw ThrowUtil.NoDocumentAssigned();
 			return heightTree.GetLineByVisualPosition(visualTop);
 		}
 	}
diff --git a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Utils/ThrowUtil.cs b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Utils/ThrowUtil.cs
index fd5d22c738..b9d27259ef 100644
--- a/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Utils/ThrowUtil.cs
+++ b/src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Utils/ThrowUtil.cs
@@ -31,5 +31,10 @@ namespace ICSharpCode.AvalonEdit.Utils
 				throw new ArgumentNullException(parameterName);
 			return val;
 		}
+		
+		public static InvalidOperationException NoDocumentAssigned()
+		{
+			throw new InvalidOperationException("Document is null");
+		}
 	}
 }