diff --git a/Directory.Build.props b/Directory.Build.props
index 5da6d0ed..f59c8bdc 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -7,7 +7,7 @@
     <IncludeSymbols>true</IncludeSymbols>
     <EmbedUntrackedSources>true</EmbedUntrackedSources>
 
-    <Version>12.0.0</Version>
+    <Version>12.0.0-iuv2001</Version>
     <Authors>Avalonia Team</Authors>
     <Copyright>Copyright 2017-$([System.DateTime]::Now.ToString(`yyyy`)) &#169; The AvaloniaUI Project</Copyright>
     <RepositoryUrl>https://github.com/AvaloniaUI/AvaloniaEdit/</RepositoryUrl>
@@ -16,6 +16,8 @@
     <SymbolPackageFormat>snupkg</SymbolPackageFormat>
     <AssemblyOriginatorKeyFile>$(MSBuildThisFileDirectory)\avalonia.snk</AssemblyOriginatorKeyFile>
     <SignAssembly>true</SignAssembly>
+    <PackageOutputPath>$(SolutionDir)AvaloniaEdit-Package\</PackageOutputPath>
+    <GeneratePackageOnBuild>True</GeneratePackageOnBuild>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(GITHUB_ACTIONS)' == 'true'">
@@ -28,4 +30,4 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.SourceLink.GitHub" PrivateAssets="All"/>
   </ItemGroup>
-</Project>
+</Project>
\ No newline at end of file
diff --git a/NuGet.config b/NuGet.config
index 6fe0770f..0a51acda 100644
--- a/NuGet.config
+++ b/NuGet.config
@@ -1,12 +1,8 @@
 <?xml version="1.0" encoding="utf-8"?>
 <configuration>
   <packageSources>
-    <clear />
-    <add key="nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" />
+    <!-- <clear /> -->
+    <!-- <add key="nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" /> -->
+    <!-- <add key="AvaloniaAll" value="https://nuget-feed-all.avaloniaui.net/v3/index.json" protocolVersion="3" /> -->
   </packageSources>
-  <packageSourceMapping>
-    <packageSource key="nuget.org">
-      <package pattern="*" />
-    </packageSource>
-  </packageSourceMapping>
 </configuration>
diff --git a/src/AvaloniaEdit.Demo/MainWindow.axaml.cs b/src/AvaloniaEdit.Demo/MainWindow.axaml.cs
index 3735f260..676ce7b5 100644
--- a/src/AvaloniaEdit.Demo/MainWindow.axaml.cs
+++ b/src/AvaloniaEdit.Demo/MainWindow.axaml.cs
@@ -1,12 +1,15 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
+using System.Linq;
 using System.Runtime.CompilerServices;
 using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Input;
 using Avalonia.Interactivity;
+using Avalonia.Markup.Xaml;
 using Avalonia.Media;
+using Avalonia.Media.Imaging;
 using AvaloniaEdit.CodeCompletion;
 using AvaloniaEdit.Demo.Resources;
 using AvaloniaEdit.Document;
@@ -15,6 +18,7 @@
 using AvaloniaEdit.Rendering;
 using AvaloniaEdit.TextMate;
 using TextMateSharp.Grammars;
+using Avalonia.Diagnostics;
 using Avalonia.Layout;
 using AvaloniaEdit.Snippets;
 using Snippet = AvaloniaEdit.Snippets.Snippet;
@@ -23,12 +27,18 @@ namespace AvaloniaEdit.Demo
 {
     using Pair = KeyValuePair<int, Control>;
 
-    public partial class MainWindow : Window
+    public class MainWindow : Window
     {
+        private readonly TextEditor _textEditor;
         private FoldingManager _foldingManager;
         private readonly TextMate.TextMate.Installation _textMateInstallation;
         private CompletionWindow _completionWindow;
         private OverloadInsightWindow _insightWindow;
+        private Button _addControlButton;
+        private Button _clearControlButton;
+        private Button _insertSnippetButton;
+        private ComboBox _syntaxModeCombo;
+        private TextBlock _statusTextBlock;
         private ElementGenerator _generator = new ElementGenerator();
         private RegistryOptions _registryOptions;
         private int _currentTheme = (int)ThemeName.DarkPlus;
@@ -38,60 +48,73 @@ public MainWindow()
         {
             InitializeComponent();
 
-            Editor.HorizontalScrollBarVisibility = Avalonia.Controls.Primitives.ScrollBarVisibility.Visible;
-            Editor.Background = Brushes.Transparent;
-            Editor.ShowLineNumbers = true;
-            Editor.TextArea.Background = this.Background;
-            Editor.TextArea.TextEntered += textEditor_TextArea_TextEntered;
-            Editor.TextArea.TextEntering += textEditor_TextArea_TextEntering;
-            Editor.Options.AllowToggleOverstrikeMode = true;
-            Editor.Options.EnableTextDragDrop = true;
-            Editor.Options.ShowBoxForControlCharacters = true;
-            Editor.Options.ColumnRulerPositions = new List<int>() { 80, 100 };
-            Editor.TextArea.IndentationStrategy = new Indentation.CSharp.CSharpIndentationStrategy(Editor.Options);
-            Editor.TextArea.Caret.PositionChanged += Caret_PositionChanged;
-            Editor.TextArea.RightClickMovesCaret = true;
-            Editor.Options.HighlightCurrentLine = true;
-            Editor.Options.CompletionAcceptAction = CompletionAcceptAction.DoubleTapped;
-
-            AddControlBtn.Click += AddControlButton_Click;
-            ClearControlBtn.Click += ClearControlButton_Click;
-            InsertSnippetBtn.Click += InsertSnippetButton_Click;
-
-            Editor.TextArea.TextView.ElementGenerators.Add(_generator);
+            this.AttachDevTools();
+
+            _textEditor = this.FindControl<TextEditor>("Editor");
+            _textEditor.HorizontalScrollBarVisibility = Avalonia.Controls.Primitives.ScrollBarVisibility.Visible;
+            _textEditor.Background = Brushes.Transparent;
+            _textEditor.ShowLineNumbers = true;
+            _textEditor.TextArea.Background = this.Background;
+            _textEditor.TextArea.TextEntered += textEditor_TextArea_TextEntered;
+            _textEditor.TextArea.TextEntering += textEditor_TextArea_TextEntering;
+            _textEditor.Options.AllowToggleOverstrikeMode = true;
+            _textEditor.Options.EnableTextDragDrop = true;
+            _textEditor.Options.ShowSpaces = false;
+            _textEditor.Options.ShowLeadingSpaces = true;
+            _textEditor.Options.ShowBoxForControlCharacters = true;
+            _textEditor.Options.ColumnRulerPositions = new List<int>() { 80, 100 };
+            _textEditor.TextArea.IndentationStrategy = new Indentation.CSharp.CSharpIndentationStrategy(_textEditor.Options);
+            _textEditor.TextArea.Caret.PositionChanged += Caret_PositionChanged;
+            _textEditor.TextArea.RightClickMovesCaret = true;
+            _textEditor.Options.HighlightCurrentLine = true;
+            _textEditor.Options.CompletionAcceptAction = CompletionAcceptAction.DoubleTapped;
+
+            _addControlButton = this.FindControl<Button>("addControlBtn");
+            _addControlButton.Click += AddControlButton_Click;
+
+            _clearControlButton = this.FindControl<Button>("clearControlBtn");
+            _clearControlButton.Click += ClearControlButton_Click;
+
+            _insertSnippetButton = this.FindControl<Button>("insertSnippetBtn");
+            _insertSnippetButton.Click += InsertSnippetButton_Click;
+
+            _textEditor.TextArea.TextView.ElementGenerators.Add(_generator);
 
             _registryOptions = new RegistryOptions(
                 (ThemeName)_currentTheme);
 
-            _textMateInstallation = Editor.InstallTextMate(_registryOptions);
+            _textMateInstallation = _textEditor.InstallTextMate(_registryOptions);
 
             _textMateInstallation.AppliedTheme += TextMateInstallationOnAppliedTheme;
 
             Language csharpLanguage = _registryOptions.GetLanguageByExtension(".cs");
 
-            SyntaxModeCombo.ItemsSource = _registryOptions.GetAvailableLanguages();
-            SyntaxModeCombo.SelectedItem = csharpLanguage;
-            SyntaxModeCombo.SelectionChanged += SyntaxModeCombo_SelectionChanged;
+            _syntaxModeCombo = this.FindControl<ComboBox>("syntaxModeCombo");
+            _syntaxModeCombo.ItemsSource = _registryOptions.GetAvailableLanguages();
+            _syntaxModeCombo.SelectedItem = csharpLanguage;
+            _syntaxModeCombo.SelectionChanged += SyntaxModeCombo_SelectionChanged;
 
             string scopeName = _registryOptions.GetScopeByLanguageId(csharpLanguage.Id);
 
-            Editor.Document = new TextDocument(
+            _textEditor.Document = new TextDocument(
                 "// AvaloniaEdit supports displaying control chars: \a or \b or \v" + Environment.NewLine +
                 "// AvaloniaEdit supports displaying underline and strikethrough" + Environment.NewLine +
                 ResourceLoader.LoadSampleFile(scopeName));
             _textMateInstallation.SetGrammar(_registryOptions.GetScopeByLanguageId(csharpLanguage.Id));
-            Editor.TextArea.TextView.LineTransformers.Add(new UnderlineAndStrikeThroughTransformer());
+            _textEditor.TextArea.TextView.LineTransformers.Add(new UnderlineAndStrikeThroughTransformer());
+
+            _statusTextBlock = this.Find<TextBlock>("StatusText");
 
             this.AddHandler(PointerWheelChangedEvent, (o, i) =>
             {
                 if (i.KeyModifiers != KeyModifiers.Control) return;
-                if (i.Delta.Y > 0) Editor.FontSize++;
-                else Editor.FontSize = Editor.FontSize > 1 ? Editor.FontSize - 1 : 1;
+                if (i.Delta.Y > 0) _textEditor.FontSize++;
+                else _textEditor.FontSize = _textEditor.FontSize > 1 ? _textEditor.FontSize - 1 : 1;
             }, RoutingStrategies.Bubble, true);
 
             // Add a custom margin at the left of the text area, which can be clicked.
             _customMargin = new CustomMargin();
-            Editor.TextArea.LeftMargins.Insert(0, _customMargin);
+            _textEditor.TextArea.LeftMargins.Insert(0, _customMargin);
 
             var mainWindowVM = new MainWindowViewModel(_textMateInstallation, _registryOptions);
             foreach (ThemeName themeName in Enum.GetValues<ThemeName>())
@@ -104,6 +127,8 @@ public MainWindow()
                 }
             }
             DataContext = mainWindowVM;
+
+
         }
 
         private void TextMateInstallationOnAppliedTheme(object sender, TextMate.TextMate.Installation e)
@@ -114,17 +139,17 @@ private void TextMateInstallationOnAppliedTheme(object sender, TextMate.TextMate
 
         void ApplyThemeColorsToEditor(TextMate.TextMate.Installation e)
         {
-            ApplyBrushAction(e, "editor.background",brush => Editor.Background = brush);
-            ApplyBrushAction(e, "editor.foreground",brush => Editor.Foreground = brush);
+            ApplyBrushAction(e, "editor.background", brush => _textEditor.Background = brush);
+            ApplyBrushAction(e, "editor.foreground", brush => _textEditor.Foreground = brush);
 
             if (!ApplyBrushAction(e, "editor.selectionBackground",
-                    brush => Editor.TextArea.SelectionBrush = brush))
+                    brush => _textEditor.TextArea.SelectionBrush = brush))
             {
                 if (Application.Current!.TryGetResource("TextAreaSelectionBrush", out var resourceObject))
                 {
                     if (resourceObject is IBrush brush)
                     {
-                        Editor.TextArea.SelectionBrush = brush;
+                        _textEditor.TextArea.SelectionBrush = brush;
                     }
                 }
             }
@@ -132,31 +157,37 @@ void ApplyThemeColorsToEditor(TextMate.TextMate.Installation e)
             if (!ApplyBrushAction(e, "editor.lineHighlightBackground",
                     brush =>
                     {
-                        Editor.TextArea.TextView.CurrentLineBackground = brush;
-                        Editor.TextArea.TextView.CurrentLineBorder = new Pen(brush); // Todo: VS Code didn't seem to have a border but it might be nice to have that option. For now just make it the same..
+                        _textEditor.TextArea.TextView.CurrentLineBackground = brush;
+                        _textEditor.TextArea.TextView.CurrentLineBorder = new Pen(brush); // Todo: VS Code didn't seem to have a border but it might be nice to have that option. For now just make it the same..
                     }))
             {
-                Editor.TextArea.TextView.SetDefaultHighlightLineColors();
+                _textEditor.TextArea.TextView.SetDefaultHighlightLineColors();
             }
 
             //Todo: looks like the margin doesn't have a active line highlight, would be a nice addition
             if (!ApplyBrushAction(e, "editorLineNumber.foreground",
-                    brush => Editor.LineNumbersForeground = brush))
+                    brush => _textEditor.LineNumbersForeground = brush))
             {
-                Editor.LineNumbersForeground = Editor.Foreground;
+                _textEditor.LineNumbersForeground = _textEditor.Foreground;
             }
         }
 
         private void ApplyThemeColorsToWindow(TextMate.TextMate.Installation e)
         {
-            if (!ApplyBrushAction(e, "statusBar.background", brush => StatusBar.Background = brush))
+            var panel = this.Find<StackPanel>("StatusBar");
+            if (panel == null)
+            {
+                return;
+            }
+
+            if (!ApplyBrushAction(e, "statusBar.background", brush => panel.Background = brush))
             {
-                StatusBar.Background = Brushes.Purple;
+                panel.Background = Brushes.Purple;
             }
 
-            if (!ApplyBrushAction(e, "statusBar.foreground", brush => StatusText.Foreground = brush))
+            if (!ApplyBrushAction(e, "statusBar.foreground", brush => _statusTextBlock.Foreground = brush))
             {
-                StatusText.Foreground = Brushes.White;
+                _statusTextBlock.Foreground = Brushes.White;
             }
 
             if (!ApplyBrushAction(e, "sideBar.background", brush => _customMargin.BackGroundBrush = brush))
@@ -165,8 +196,8 @@ private void ApplyThemeColorsToWindow(TextMate.TextMate.Installation e)
             }
 
             //Applying the Editor background to the whole window for demo sake.
-            ApplyBrushAction(e, "editor.background",brush => Background = brush);
-            ApplyBrushAction(e, "editor.foreground",brush => Foreground = brush);
+            ApplyBrushAction(e, "editor.background", brush => Background = brush);
+            ApplyBrushAction(e, "editor.foreground", brush => Foreground = brush);
         }
 
         bool ApplyBrushAction(TextMate.TextMate.Installation e, string colorKeyNameFromJson, Action<IBrush> applyColorAction)
@@ -184,9 +215,9 @@ bool ApplyBrushAction(TextMate.TextMate.Installation e, string colorKeyNameFromJ
 
         private void Caret_PositionChanged(object sender, EventArgs e)
         {
-            StatusText.Text = string.Format("Line {0} Column {1}",
-                Editor.TextArea.Caret.Line,
-                Editor.TextArea.Caret.Column);
+            _statusTextBlock.Text = string.Format("Line {0} Column {1}",
+                _textEditor.TextArea.Caret.Line,
+                _textEditor.TextArea.Caret.Column);
         }
 
         protected override void OnClosed(EventArgs e)
@@ -200,7 +231,7 @@ private void SyntaxModeCombo_SelectionChanged(object sender, SelectionChangedEve
         {
             RemoveUnderlineAndStrikethroughTransformer();
 
-            Language language = (Language)SyntaxModeCombo.SelectedItem;
+            Language language = (Language)_syntaxModeCombo.SelectedItem;
 
             if (_foldingManager != null)
             {
@@ -211,30 +242,35 @@ private void SyntaxModeCombo_SelectionChanged(object sender, SelectionChangedEve
             string scopeName = _registryOptions.GetScopeByLanguageId(language.Id);
 
             _textMateInstallation.SetGrammar(null);
-            Editor.Document = new TextDocument(ResourceLoader.LoadSampleFile(scopeName));
+            _textEditor.Document = new TextDocument(ResourceLoader.LoadSampleFile(scopeName));
             _textMateInstallation.SetGrammar(scopeName);
 
             if (language.Id == "xml")
             {
-                _foldingManager = FoldingManager.Install(Editor.TextArea);
+                _foldingManager = FoldingManager.Install(_textEditor.TextArea);
 
                 var strategy = new XmlFoldingStrategy();
-                strategy.UpdateFoldings(_foldingManager, Editor.Document);
+                strategy.UpdateFoldings(_foldingManager, _textEditor.Document);
                 return;
             }
         }
 
         private void RemoveUnderlineAndStrikethroughTransformer()
         {
-            for (int i = Editor.TextArea.TextView.LineTransformers.Count - 1; i >= 0; i--)
+            for (int i = _textEditor.TextArea.TextView.LineTransformers.Count - 1; i >= 0; i--)
             {
-                if (Editor.TextArea.TextView.LineTransformers[i] is UnderlineAndStrikeThroughTransformer)
+                if (_textEditor.TextArea.TextView.LineTransformers[i] is UnderlineAndStrikeThroughTransformer)
                 {
-                    Editor.TextArea.TextView.LineTransformers.RemoveAt(i);
+                    _textEditor.TextArea.TextView.LineTransformers.RemoveAt(i);
                 }
             }
         }
 
+        private void InitializeComponent()
+        {
+            AvaloniaXamlLoader.Load(this);
+        }
+
         private void AddControlButton_Click(object sender, RoutedEventArgs e)
         {
             var button = new Button() { Content = "Click me", Cursor = Cursor.Default };
@@ -246,16 +282,16 @@ private void AddControlButton_Click(object sender, RoutedEventArgs e)
             // of all elements within a line.
             TextBlock.SetBaselineOffset(button, 22);
 
-            _generator.controls.Add(new Pair(Editor.CaretOffset, button));
+            _generator.controls.Add(new Pair(_textEditor.CaretOffset, button));
             _generator.controls.Sort(0, _generator.controls.Count, _generator);
-            Editor.TextArea.TextView.Redraw();
+            _textEditor.TextArea.TextView.Redraw();
         }
 
         private void ClearControlButton_Click(object sender, RoutedEventArgs e)
         {
             //TODO: delete elements using back key
             _generator.controls.Clear();
-            Editor.TextArea.TextView.Redraw();
+            _textEditor.TextArea.TextView.Redraw();
         }
 
         private void textEditor_TextArea_TextEntering(object sender, TextInputEventArgs e)
@@ -281,7 +317,7 @@ private void textEditor_TextArea_TextEntered(object sender, TextInputEventArgs e
             if (e.Text == ".")
             {
 
-                _completionWindow = new CompletionWindow(Editor.TextArea);
+                _completionWindow = new CompletionWindow(_textEditor.TextArea);
                 _completionWindow.Closed += (o, args) => _completionWindow = null;
 
                 var data = _completionWindow.CompletionList.CompletionData;
@@ -297,7 +333,7 @@ private void textEditor_TextArea_TextEntered(object sender, TextInputEventArgs e
             }
             else if (e.Text == "(")
             {
-                _insightWindow = new OverloadInsightWindow(Editor.TextArea);
+                _insightWindow = new OverloadInsightWindow(_textEditor.TextArea);
                 _insightWindow.Closed += (o, args) => _insightWindow = null;
 
                 _insightWindow.Provider = new MyOverloadProvider(new[]
@@ -370,6 +406,7 @@ protected override void ColorizeLine(DocumentLine line)
         private class MyOverloadProvider : IOverloadProvider
         {
             private readonly IList<(string header, string content)> _items;
+            private int _selectedIndex;
 
             public MyOverloadProvider(IList<(string header, string content)> items)
             {
@@ -379,10 +416,10 @@ public MyOverloadProvider(IList<(string header, string content)> items)
 
             public int SelectedIndex
             {
-                get;
+                get => _selectedIndex;
                 set
                 {
-                    field = value;
+                    _selectedIndex = value;
                     OnPropertyChanged();
                     // ReSharper disable ExplicitCallerInfoArgument
                     OnPropertyChanged(nameof(CurrentHeader));
@@ -495,8 +532,8 @@ private void InsertSnippetButton_Click(object sender, RoutedEventArgs e)
                 }
             };
 
-            snippet.Insert(Editor.TextArea);
-            Editor.Focus();
+            snippet.Insert(_textEditor.TextArea);
+            _textEditor.Focus();
         }
     }
 }
diff --git a/src/AvaloniaEdit.TextMate/AvaloniaEdit.TextMate.csproj b/src/AvaloniaEdit.TextMate/AvaloniaEdit.TextMate.csproj
index 4691c9ff..243e7cc5 100644
--- a/src/AvaloniaEdit.TextMate/AvaloniaEdit.TextMate.csproj
+++ b/src/AvaloniaEdit.TextMate/AvaloniaEdit.TextMate.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net8.0;net10.0</TargetFrameworks>
+    <TargetFrameworks>net9.0;net10.0</TargetFrameworks>
     <PackageDescription>TextMate integration for AvaloniaEdit.</PackageDescription>
   </PropertyGroup>
 
diff --git a/src/AvaloniaEdit/AvaloniaEdit.csproj b/src/AvaloniaEdit/AvaloniaEdit.csproj
index 218c395d..732742e3 100644
--- a/src/AvaloniaEdit/AvaloniaEdit.csproj
+++ b/src/AvaloniaEdit/AvaloniaEdit.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net8.0;net10.0</TargetFrameworks>
+    <TargetFrameworks>net9.0;net10.0</TargetFrameworks>
     <WarningsNotAsErrors>0612,0618</WarningsNotAsErrors>
     <PackageId>Avalonia.AvaloniaEdit</PackageId>
     <PackageDescription>This project is a port of AvalonEdit, a WPF-based text editor for Avalonia.</PackageDescription>
diff --git a/src/AvaloniaEdit/Folding/FoldingManager.cs b/src/AvaloniaEdit/Folding/FoldingManager.cs
index 87b04cf3..bdee9282 100644
--- a/src/AvaloniaEdit/Folding/FoldingManager.cs
+++ b/src/AvaloniaEdit/Folding/FoldingManager.cs
@@ -331,6 +331,7 @@ public FoldingManagerInstallation(TextArea textArea) : base(textArea.Document)
             {
                 _textArea = textArea;
                 _margin = new FoldingMargin { FoldingManager = this };
+                _margin.OnFoldedChanged += RaiseOnFoldedChanged;
                 _generator = new FoldingElementGenerator { FoldingManager = this };
                 textArea.LeftMargins.Add(_margin);
                 textArea.TextView.Services.AddService(typeof(FoldingManager), this);
@@ -392,5 +393,19 @@ private void TextArea_Caret_PositionChanged(object sender, EventArgs e)
             }
         }
         #endregion
+
+        #region Event
+        /// <summary>
+        /// 代码折叠事件
+        /// </summary>
+        public event EventHandler OnFoldedChanged;
+        private void RaiseOnFoldedChanged(object sender, EventArgs e)
+        {
+            if (OnFoldedChanged != null)
+            {
+                OnFoldedChanged(this, e);
+            }
+        }
+        #endregion
     }
 }
diff --git a/src/AvaloniaEdit/Folding/FoldingMargin.cs b/src/AvaloniaEdit/Folding/FoldingMargin.cs
index 24a9d580..ce18fd08 100644
--- a/src/AvaloniaEdit/Folding/FoldingMargin.cs
+++ b/src/AvaloniaEdit/Folding/FoldingMargin.cs
@@ -16,6 +16,7 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using Avalonia;
@@ -40,6 +41,8 @@ public class FoldingMargin : AbstractMargin
 
         internal const double SizeFactor = Constants.PixelPerPoint;
 
+        public event EventHandler OnFoldedChanged;
+
         static FoldingMargin()
         {
             FoldingMarkerBrushProperty.Changed.Subscribe(OnUpdateBrushes);
@@ -165,6 +168,7 @@ protected override void OnTextViewVisualLinesChanged()
         {
             foreach (var m in _markers)
             {
+                m.OnFoldedChanged -= RaiseOnFoldedChanged;
                 VisualChildren.Remove(m);
             }
 
@@ -185,6 +189,7 @@ protected override void OnTextViewVisualLinesChanged()
                         };
                         ((ISetLogicalParent)m).SetParent(this);
 
+                        m.OnFoldedChanged += RaiseOnFoldedChanged;
                         _markers.Add(m);
                         VisualChildren.Add(m);
 
@@ -202,6 +207,11 @@ protected override void OnTextViewVisualLinesChanged()
             }
         }
 
+        private void RaiseOnFoldedChanged(object sender, EventArgs e)
+        {
+            OnFoldedChanged?.Invoke(this, e);
+        }
+
         private Pen _foldingControlPen = new Pen(FoldingMarkerBrushProperty.GetDefaultValue(typeof(FoldingMargin)));
         private Pen _selectedFoldingControlPen = new Pen(SelectedFoldingMarkerBrushProperty.GetDefaultValue(typeof(FoldingMargin)));
 
diff --git a/src/AvaloniaEdit/Folding/FoldingMarginMarker.cs b/src/AvaloniaEdit/Folding/FoldingMarginMarker.cs
index 9623f6ee..8ff64c68 100644
--- a/src/AvaloniaEdit/Folding/FoldingMarginMarker.cs
+++ b/src/AvaloniaEdit/Folding/FoldingMarginMarker.cs
@@ -17,11 +17,12 @@
 // DEALINGS IN THE SOFTWARE.
 
 using Avalonia;
-using AvaloniaEdit.Rendering;
-using AvaloniaEdit.Utils;
 using Avalonia.Controls;
 using Avalonia.Input;
 using Avalonia.Media;
+using AvaloniaEdit.Rendering;
+using AvaloniaEdit.Utils;
+using System;
 
 namespace AvaloniaEdit.Folding
 {
@@ -32,6 +33,8 @@ internal sealed class FoldingMarginMarker : Control
 
         private bool _isExpanded;
 
+        public event EventHandler OnFoldedChanged;
+
         public bool IsExpanded
         {
             get => _isExpanded;
@@ -43,7 +46,10 @@ public bool IsExpanded
                     InvalidateVisual();
                 }
                 if (FoldingSection != null)
+                {
                     FoldingSection.IsFolded = !value;
+                    OnFoldedChanged?.Invoke(this, EventArgs.Empty);
+                }
             }
         }
 
diff --git a/src/AvaloniaEdit/Highlighting/Resources/QFormula.xshd b/src/AvaloniaEdit/Highlighting/Resources/QFormula.xshd
new file mode 100644
index 00000000..1873657e
--- /dev/null
+++ b/src/AvaloniaEdit/Highlighting/Resources/QFormula.xshd
@@ -0,0 +1,258 @@
+<?xml version="1.0"?>
+<SyntaxDefinition name="Python" extensions=".py;.pyw" xmlns="http://icsharpcode.net/sharpdevelop/syntaxdefinition/2008">
+  <Color name="Comment" foreground="Green" exampleText="# comment"/>
+  <Color name="String" foreground="Gray" exampleText="name = 'abc'"/>
+  <Color name="MethodCall" foreground="Purple" exampleText="def Hello()"/>
+  <Color name="NumberLiteral" foreground="DarkBlue" exampleText="3.1415f"/>
+  <Color name="Keywords" fontWeight="bold" foreground="Blue" exampleText="if"/>
+  <Color name="Operators" foreground="#DCDCDC" exampleText=""/>
+  <Color name="IndicatorKeys" foreground="#DF6836" exampleText=""/>
+  <Color name="IndicatorNames" foreground="#DF6836" exampleText=""/>
+
+  <Property name="DocCommentMarker" value="///"/>
+
+  <RuleSet name="CommentMarkerSet">
+    <Keywords fontWeight="bold" foreground="Red">
+      <Word>TODO</Word>
+      <Word>FIXME</Word>
+    </Keywords>
+    <Keywords fontWeight="bold" foreground="#E0E000">
+      <Word>HACK</Word>
+      <Word>UNDONE</Word>
+    </Keywords>
+  </RuleSet>
+
+  <RuleSet>
+    <Span color="Comment" ruleSet="CommentMarkerSet">
+      <Begin>\#</Begin>
+    </Span>
+
+    <Span color="String" multiline="true">
+      <Begin>'''</Begin>
+      <End>'''</End>
+    </Span>
+    <Span color="String" multiline="true">
+      <Begin>"""</Begin>
+      <End>"""</End>
+    </Span>
+
+    <Span color="String">
+      <Begin>"</Begin>
+      <End>"</End>
+      <RuleSet>
+        <Span begin="\\" end="."/>
+      </RuleSet>
+    </Span>
+    <Span color="String">
+      <Begin>'</Begin>
+      <End>'</End>
+      <RuleSet>
+        <Span begin="\\" end="."/>
+      </RuleSet>
+    </Span>
+
+    <Keywords color="Keywords">
+      <Word>and</Word>
+      <Word>as</Word>
+      <Word>assert</Word>
+      <Word>break</Word>
+      <Word>class</Word>
+      <Word>continue</Word>
+      <Word>def</Word>
+      <Word>del</Word>
+      <Word>elif</Word>
+      <Word>else</Word>
+      <Word>except</Word>
+      <Word>exec</Word>
+      <Word>False</Word>
+      <Word>finally</Word>
+      <Word>for</Word>
+      <Word>from</Word>
+      <Word>global</Word>
+      <Word>if</Word>
+      <Word>import</Word>
+      <Word>in</Word>
+      <Word>is</Word>
+      <Word>lambda</Word>
+      <Word>None</Word>
+      <Word>nonlocal</Word>
+      <Word>not</Word>
+      <Word>or</Word>
+      <Word>pass</Word>
+      <Word>print</Word>
+      <Word>raise</Word>
+      <Word>return</Word>
+      <Word>True</Word>
+      <Word>try</Word>
+      <Word>while</Word>
+      <Word>with</Word>
+      <Word>yield</Word>
+      <Word>async</Word>
+      <Word>await</Word>
+    </Keywords>
+
+    <Keywords color="IndicatorKeys">
+      <Word>OPEN</Word>
+      <Word>O</Word>
+      <Word>HIGH</Word>
+      <Word>H</Word>
+      <Word>LOW</Word>
+      <Word>L</Word>
+      <Word>CLOSE</Word>
+      <Word>C</Word>
+      <Word>VOL</Word>
+      <Word>V</Word>
+      <Word>AMOUNT</Word>
+      <Word>PERIOD</Word>
+      <Word>DATE</Word>
+      <Word>DAY</Word>
+      <Word>HOUR</Word>
+      <Word>MINUTE</Word>
+      <Word>MONTH</Word>
+      <Word>TIME</Word>
+      <Word>YEAR</Word>
+      <Word>WEEKDAY</Word>
+      <Word>DRAWNULL</Word>
+      <Word>BACKSET</Word>
+      <Word>BARSCOUNT</Word>
+      <Word>BARSTATUS</Word>
+      <Word>BARSSINCE</Word>
+      <Word>BARSSINCEN</Word>
+      <Word>BARSLAST</Word>
+      <Word>BARSLASTCOUNT</Word>
+      <Word>BARSNEXT</Word>
+      <Word>CURRBARSCOUNT</Word>
+      <Word>COUNT</Word>
+      <Word>CONST</Word>
+      <Word>DMA</Word>
+      <Word>EMA</Word>
+      <Word>HHV</Word>
+      <Word>HHVBARS</Word>
+      <Word>HOD</Word>
+      <Word>ISLASTBAR</Word>
+      <Word>LLV</Word>
+      <Word>LLVBARS</Word>
+      <Word>LOD</Word>
+      <Word>LOWRANGE</Word>
+      <Word>MA</Word>
+      <Word>MEMA</Word>
+      <Word>EXPMEMA</Word>
+      <Word>MULAR</Word>
+      <Word>RANGE</Word>
+      <Word>REFV</Word>
+      <Word>REFXV</Word>
+      <Word>REFX</Word>
+      <Word>REF</Word>
+      <Word>REVERSE</Word>
+      <Word>SMA</Word>
+      <Word>SUMBARS</Word>
+      <Word>SUM</Word>
+      <Word>TMA</Word>
+      <Word>WMA</Word>
+      <Word>CROSS</Word>
+      <Word>LONGCROSS</Word>
+      <Word>UPNDAY</Word>
+      <Word>DOWNNDAY</Word>
+      <Word>NDAY</Word>
+      <Word>EXIST</Word>
+      <Word>EVERY</Word>
+      <Word>NOT</Word>
+      <Word>IFC</Word>
+      <Word>IF</Word>
+      <Word>IFF</Word>
+      <Word>IFN</Word>
+      <Word>ABS</Word>
+      <Word>ACOS</Word>
+      <Word>ASIN</Word>
+      <Word>ATAN</Word>
+      <Word>BETWEEN</Word>
+      <Word>CEILING</Word>
+      <Word>COS</Word>
+      <Word>EXP</Word>
+      <Word>FLOOR</Word>
+      <Word>FRACPART</Word>
+      <Word>INTPART</Word>
+      <Word>LN</Word>
+      <Word>LOG</Word>
+      <Word>MAX</Word>
+      <Word>MIN</Word>
+      <Word>MOD</Word>
+      <Word>POW</Word>
+      <Word>RAND</Word>
+      <Word>ROUND</Word>
+      <Word>SIGN</Word>
+      <Word>SIN</Word>
+      <Word>SQRT</Word>
+      <Word>TAN</Word>
+      <Word>AVEDEV</Word>
+      <Word>DEVSQ</Word>
+      <Word>FORCAST</Word>
+      <Word>SLOPE</Word>
+      <Word>STD</Word>
+      <Word>STDP</Word>
+      <Word>VAR</Word>
+      <Word>VARP</Word>
+      <Word>COVAR</Word>
+      <Word>SAR</Word>
+      <Word>DYNAINFO</Word>
+      <Word>INFORMATION</Word>
+    </Keywords>
+    <Keywords color="IndicatorNames">
+      <Word>MACD</Word>
+      <Word>KDJ</Word>
+      <Word>RSI</Word>
+      <Word>BOLL</Word>
+      <Word>DMI</Word>
+      <Word>BIAS</Word>
+      <Word>ASI</Word>
+      <Word>OBV</Word>
+      <Word>WAD</Word>
+      <Word>PSY</Word>
+      <Word>ATR</Word>
+      <Word>PVI</Word>
+      <Word>SAR</Word>
+      <Word>TRIX</Word>
+      <Word>ARBR</Word>
+      <Word>VR</Word>
+      <Word>DPO</Word>
+      <Word>DMA</Word>
+      <Word>BBI</Word>
+      <Word>MTM</Word>
+      <Word>MA</Word>
+      <Word>WR</Word>
+      <Word>DKX</Word>
+      <Word>ENE</Word>
+      <Word>EXPMA</Word>
+    </Keywords>
+    <Keywords color="Operators">
+      <Word>+</Word>
+      <Word>-</Word>
+      <Word>*</Word>
+      <Word>/</Word>
+      <Word>></Word>
+      <Word>&lt;</Word>
+      <Word>=</Word>
+      <Word>(</Word>
+      <Word>)</Word>
+      <Word>\</Word>
+      <Word>:</Word>
+      <Word>;</Word>
+      <Word>,</Word>
+      <Word>|</Word>
+      <Word>&amp;</Word>
+    </Keywords>
+
+    <Rule color="MethodCall">
+      \b
+      [\d\w_]+  # an identifier
+      (?=\s*\() # followed by (
+    </Rule>
+    <Rule color="NumberLiteral">
+      \b0[xX][0-9a-fA-F]+  # hex number
+      (	\b\d+(\.[0-9]+)?   #number with optional floating point
+      |	\.[0-9]+           #or just starting with floating point
+      )
+      ([eE][+-]?[0-9]+)? # optional exponent
+    </Rule>
+  </RuleSet>
+</SyntaxDefinition>
diff --git a/src/AvaloniaEdit/Highlighting/Resources/Resources.cs b/src/AvaloniaEdit/Highlighting/Resources/Resources.cs
index b30a3da4..ed440db8 100644
--- a/src/AvaloniaEdit/Highlighting/Resources/Resources.cs
+++ b/src/AvaloniaEdit/Highlighting/Resources/Resources.cs
@@ -52,7 +52,8 @@ internal static void RegisterBuiltInHighlightings(HighlightingManager.DefaultHig
 			hlm.RegisterHighlighting("PowerShell", new[] { ".ps1", ".psm1", ".psd1" }, "PowerShell.xshd");
 			hlm.RegisterHighlighting("PHP", new[] { ".php" }, "PHP-Mode.xshd");
 			hlm.RegisterHighlighting("Python", new[] { ".py", ".pyw" }, "Python-Mode.xshd");
-			hlm.RegisterHighlighting("TeX", new[] { ".tex" }, "Tex-Mode.xshd");
+            hlm.RegisterHighlighting("QFormula", new[] { ".f"}, "QFormula.xshd");
+            hlm.RegisterHighlighting("TeX", new[] { ".tex" }, "Tex-Mode.xshd");
 			hlm.RegisterHighlighting("TSQL", new[] { ".sql" }, "TSQL-Mode.xshd");
 			hlm.RegisterHighlighting("VB", new[] { ".vb" }, "VB-Mode.xshd");
 			hlm.RegisterHighlighting("XML", (".xml;.xsl;.xslt;.xsd;.manifest;.config;.addin;" +
diff --git a/src/AvaloniaEdit/Rendering/SingleCharacterElementGenerator.cs b/src/AvaloniaEdit/Rendering/SingleCharacterElementGenerator.cs
index f5d9c1ba..413ca25b 100644
--- a/src/AvaloniaEdit/Rendering/SingleCharacterElementGenerator.cs
+++ b/src/AvaloniaEdit/Rendering/SingleCharacterElementGenerator.cs
@@ -16,211 +16,242 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 // DEALINGS IN THE SOFTWARE.
 
-using System;
-using System.Diagnostics.CodeAnalysis;
 using Avalonia;
 using Avalonia.Media;
 using Avalonia.Media.Immutable;
 using Avalonia.Media.TextFormatting;
 using AvaloniaEdit.Document;
+using AvaloniaEdit.Utils;
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
 using LogicalDirection = AvaloniaEdit.Document.LogicalDirection;
 
 namespace AvaloniaEdit.Rendering
 {
     // This class is internal because it does not need to be accessed by the user - it can be configured using TextEditorOptions.
 
-	/// <summary>
-	/// Element generator that displays · for spaces and » for tabs and a box for control characters.
-	/// </summary>
-	/// <remarks>
-	/// This element generator is present in every TextView by default; the enabled features can be configured using the
-	/// <see cref="TextEditorOptions"/>.
-	/// </remarks>
-	[SuppressMessage("Microsoft.Naming", "CA1702:CompoundWordsShouldBeCasedCorrectly", MessageId = "Whitespace")]
-	internal sealed class SingleCharacterElementGenerator : VisualLineElementGenerator, IBuiltinElementGenerator
-	{
-		/// <summary>
-		/// Gets/Sets whether to show · for spaces.
-		/// </summary>
-		public bool ShowSpaces { get; set; }
-
-		/// <summary>
-		/// Gets/Sets whether to show » for tabs.
-		/// </summary>
-		public bool ShowTabs { get; set; }
-
-		/// <summary>
-		/// Gets/Sets whether to show a box with the hex code for control characters.
-		/// </summary>
-		public bool ShowBoxForControlCharacters { get; set; }
-
-		/// <summary>
-		/// Creates a new SingleCharacterElementGenerator instance.
-		/// </summary>
-		public SingleCharacterElementGenerator()
-		{
-			ShowSpaces = true;
-			ShowTabs = true;
-			ShowBoxForControlCharacters = true;
-		}
-
-		void IBuiltinElementGenerator.FetchOptions(TextEditorOptions options)
-		{
-			ShowSpaces = options.ShowSpaces;
-			ShowTabs = options.ShowTabs;
-			ShowBoxForControlCharacters = options.ShowBoxForControlCharacters;
-		}
-
-		public override int GetFirstInterestedOffset(int startOffset)
-		{
-			var endLine = CurrentContext.VisualLine.LastDocumentLine;
-			var relevantText = CurrentContext.GetText(startOffset, endLine.EndOffset - startOffset);
-
-			for (var i = 0; i < relevantText.Count; i++) {
-				var c = relevantText.Text[relevantText.Offset + i];
-				switch (c) {
-					case ' ':
-						if (ShowSpaces)
-							return startOffset + i;
-						break;
-					case '\t':
-						if (ShowTabs)
-							return startOffset + i;
-						break;
-					default:
-						if (ShowBoxForControlCharacters && char.IsControl(c)) {
-							return startOffset + i;
-						}
-						break;
-				}
-			}
-			return -1;
-		}
+    /// <summary>
+    /// Element generator that displays · for spaces and » for tabs and a box for control characters.
+    /// </summary>
+    /// <remarks>
+    /// This element generator is present in every TextView by default; the enabled features can be configured using the
+    /// <see cref="TextEditorOptions"/>.
+    /// </remarks>
+    [SuppressMessage("Microsoft.Naming", "CA1702:CompoundWordsShouldBeCasedCorrectly", MessageId = "Whitespace")]
+    internal sealed class SingleCharacterElementGenerator : VisualLineElementGenerator, IBuiltinElementGenerator
+    {
+        /// <summary>
+        /// Gets/Sets whether to show · for spaces.
+        /// </summary>
+        public bool ShowSpaces { get; set; }
+
+        /// <summary>
+        /// Gets/Sets whether to show · for leading spaces.
+        /// </summary>
+        public bool ShowLeadingSpaces { get; set; }
+
+        /// <summary>
+        /// Gets/Sets whether to show » for tabs.
+        /// </summary>
+        public bool ShowTabs { get; set; }
+
+        /// <summary>
+        /// Gets/Sets whether to show a box with the hex code for control characters.
+        /// </summary>
+        public bool ShowBoxForControlCharacters { get; set; }
+
+        /// <summary>
+        /// Creates a new SingleCharacterElementGenerator instance.
+        /// </summary>
+        public SingleCharacterElementGenerator()
+        {
+            ShowSpaces = true;
+            ShowLeadingSpaces = true;
+            ShowTabs = true;
+            ShowBoxForControlCharacters = true;
+        }
+
+        void IBuiltinElementGenerator.FetchOptions(TextEditorOptions options)
+        {
+            ShowSpaces = options.ShowSpaces;
+            ShowTabs = options.ShowTabs;
+            ShowLeadingSpaces = options.ShowLeadingSpaces;
+            ShowBoxForControlCharacters = options.ShowBoxForControlCharacters;
+        }
+
+        public override int GetFirstInterestedOffset(int startOffset)
+        {
+            var endLine = CurrentContext.VisualLine.LastDocumentLine;
+            var relevantText = CurrentContext.GetText(startOffset, endLine.EndOffset - startOffset);
+
+            for (var i = 0; i < relevantText.Count; i++)
+            {
+                var c = relevantText.Text[relevantText.Offset + i];
+                switch (c)
+                {
+                    case ' ':
+                        if (ShowSpaces || ShowLeadingSpaces)
+                            return startOffset + i;
+                        break;
+                    case '\t':
+                        if (ShowTabs)
+                            return startOffset + i;
+                        break;
+                    default:
+                        if (ShowBoxForControlCharacters && char.IsControl(c))
+                        {
+                            return startOffset + i;
+                        }
+                        break;
+                }
+            }
+            return -1;
+        }
 
         public override VisualLineElement ConstructElement(int offset)
         {
             var c = CurrentContext.Document.GetCharAt(offset);
 
-			if (ShowSpaces && (c == ' '))
-			{
-				var properties = new VisualLineElementTextRunProperties(CurrentContext.GlobalTextRunProperties);
-				properties.SetForegroundBrush(CurrentContext.TextView.NonPrintableCharacterBrush);
-				var textSource = new SimpleTextSource(CurrentContext.TextView.Options.ShowSpacesGlyph, properties);
-				var textLine = TextFormatter.Current.FormatLine(textSource, 0, double.MaxValue, new GenericTextParagraphProperties(properties));
-				return new SpaceTextElement(textLine);
-			}
-			
-			if (ShowTabs && (c == '\t'))
-			{
-				var properties = new VisualLineElementTextRunProperties(CurrentContext.GlobalTextRunProperties);
-				properties.SetForegroundBrush(CurrentContext.TextView.NonPrintableCharacterBrush);
-				var textSource = new SimpleTextSource(CurrentContext.TextView.Options.ShowTabsGlyph, properties);
-				var textLine = TextFormatter.Current.FormatLine(textSource, 0, double.MaxValue, new GenericTextParagraphProperties(properties));
-				return new TabTextElement(textLine);
-			}
-
-			if (ShowBoxForControlCharacters && char.IsControl(c))
-			{
-				var properties = new VisualLineElementTextRunProperties(CurrentContext.GlobalTextRunProperties);
-				properties.SetForegroundBrush(Brushes.White);
-				var textSource = new SimpleTextSource(TextUtilities.GetControlCharacterName(c), properties);
-				var textLine = TextFormatter.Current.FormatLine(textSource, 0, double.MaxValue, new GenericTextParagraphProperties(properties));
-				return new SpecialCharacterBoxElement(textLine);
-			}
+            if (c == ' ')
+            {
+                if (ShowSpaces)
+                {
+                    var runProperties = new VisualLineElementTextRunProperties(CurrentContext.GlobalTextRunProperties);
+                    runProperties.SetForegroundBrush(CurrentContext.TextView.NonPrintableCharacterBrush);
+                    return new SpaceTextElement(CurrentContext.TextView.CachedElements.GetTextForNonPrintableCharacter(
+                            CurrentContext.TextView.Options.ShowSpacesGlyph,
+                            runProperties));
+                }
+                else if (ShowLeadingSpaces)
+                {
+                    var line = CurrentContext.Document.GetLineByOffset(offset);
+                    var leadingText = CurrentContext.Document.GetText(line.Offset, offset - line.Offset);
+
+                    if (leadingText.Any(_ => _ != ' '))
+                    {
+                        return null;
+                    }
+                    else
+                    {
+                        var runProperties = new VisualLineElementTextRunProperties(CurrentContext.GlobalTextRunProperties);
+                        runProperties.SetForegroundBrush(CurrentContext.TextView.NonPrintableCharacterBrush);
+                        return new SpaceTextElement(CurrentContext.TextView.CachedElements.GetTextForNonPrintableCharacter(
+                            CurrentContext.TextView.Options.ShowSpacesGlyph,
+                            runProperties));
+                    }
+                }
+            }
+            else if (ShowTabs && c == '\t')
+            {
+                var runProperties = new VisualLineElementTextRunProperties(CurrentContext.GlobalTextRunProperties);
+                runProperties.SetForegroundBrush(CurrentContext.TextView.NonPrintableCharacterBrush);
+                return new TabTextElement(CurrentContext.TextView.CachedElements.GetTextForNonPrintableCharacter(
+                        CurrentContext.TextView.Options.ShowTabsGlyph,
+                        runProperties));
+            }
+            else if (ShowBoxForControlCharacters && char.IsControl(c))
+            {
+                var runProperties = new VisualLineElementTextRunProperties(CurrentContext.GlobalTextRunProperties);
+                runProperties.SetForegroundBrush(Brushes.White);
+                var textFormatter = TextFormatterFactory.Create(CurrentContext.TextView);
+                var text = FormattedTextElement.PrepareText(textFormatter, TextUtilities.GetControlCharacterName(c), runProperties);
+                return new SpecialCharacterBoxElement(text);
+            }
 
             return null;
         }
 
         private sealed class SpaceTextElement : FormattedTextElement
-		{
-			public SpaceTextElement(TextLine textLine) : base(textLine, 1)
-			{
-			}
-
-			public override int GetNextCaretPosition(int visualColumn, LogicalDirection direction, CaretPositioningMode mode)
-			{
-				if (mode == CaretPositioningMode.Normal || mode == CaretPositioningMode.EveryCodepoint)
-					return base.GetNextCaretPosition(visualColumn, direction, mode);
-				else
-					return -1;
-			}
-
-			public override bool IsWhitespace(int visualColumn)
-			{
-				return true;
-			}
-		}
-
-		private sealed class TabTextElement : VisualLineElement
-		{
-			internal readonly TextLine Text;
-
-			public TabTextElement(TextLine text) : base(2, 1)
-			{
-				Text = text;
-			}
-
-			public override TextRun CreateTextRun(int startVisualColumn, ITextRunConstructionContext context)
-			{
-				// the TabTextElement consists of two TextRuns:
-				// first a TabGlyphRun, then TextCharacters '\t' to let WPF handle the tab indentation
-				if (startVisualColumn == VisualColumn)
-					return new TabGlyphRun(this, TextRunProperties);
-				else if (startVisualColumn == VisualColumn + 1)
-					return new TextCharacters("\t".AsMemory(), TextRunProperties);
-				else
-					throw new ArgumentOutOfRangeException(nameof(startVisualColumn));
-			}
-
-			public override int GetNextCaretPosition(int visualColumn, LogicalDirection direction, CaretPositioningMode mode)
-			{
-				if (mode == CaretPositioningMode.Normal || mode == CaretPositioningMode.EveryCodepoint)
-					return base.GetNextCaretPosition(visualColumn, direction, mode);
-				else
-					return -1;
-			}
-
-			public override bool IsWhitespace(int visualColumn)
-			{
-				return true;
-			}
-		}
-
-		private sealed class TabGlyphRun : DrawableTextRun
-		{
-			private readonly TabTextElement _element;
-
-			public TabGlyphRun(TabTextElement element, TextRunProperties properties)
-			{
-				if (properties == null)
-					throw new ArgumentNullException(nameof(properties));
-				Properties = properties;
-				_element = element;
-			}
+        {
+            public SpaceTextElement(TextLine textLine) : base(textLine, 1)
+            {
+            }
+
+            public override int GetNextCaretPosition(int visualColumn, LogicalDirection direction, CaretPositioningMode mode)
+            {
+                if (mode == CaretPositioningMode.Normal || mode == CaretPositioningMode.EveryCodepoint)
+                    return base.GetNextCaretPosition(visualColumn, direction, mode);
+                else
+                    return -1;
+            }
+
+            public override bool IsWhitespace(int visualColumn)
+            {
+                return true;
+            }
+        }
+
+        private sealed class TabTextElement : VisualLineElement
+        {
+            internal readonly TextLine Text;
+
+            public TabTextElement(TextLine text) : base(2, 1)
+            {
+                Text = text;
+            }
+
+            public override TextRun CreateTextRun(int startVisualColumn, ITextRunConstructionContext context)
+            {
+                // the TabTextElement consists of two TextRuns:
+                // first a TabGlyphRun, then TextCharacters '\t' to let WPF handle the tab indentation
+                if (startVisualColumn == VisualColumn)
+                    return new TabGlyphRun(this, TextRunProperties);
+                else if (startVisualColumn == VisualColumn + 1)
+                    return new TextCharacters("\t".AsMemory(), TextRunProperties);
+                else
+                    throw new ArgumentOutOfRangeException(nameof(startVisualColumn));
+            }
+
+            public override int GetNextCaretPosition(int visualColumn, LogicalDirection direction, CaretPositioningMode mode)
+            {
+                if (mode == CaretPositioningMode.Normal || mode == CaretPositioningMode.EveryCodepoint)
+                    return base.GetNextCaretPosition(visualColumn, direction, mode);
+                else
+                    return -1;
+            }
+
+            public override bool IsWhitespace(int visualColumn)
+            {
+                return true;
+            }
+        }
+
+        private sealed class TabGlyphRun : DrawableTextRun
+        {
+            private readonly TabTextElement _element;
+
+            public TabGlyphRun(TabTextElement element, TextRunProperties properties)
+            {
+                if (properties == null)
+                    throw new ArgumentNullException(nameof(properties));
+                Properties = properties;
+                _element = element;
+            }
 
             public override TextRunProperties Properties { get; }
 
-			public override double Baseline => _element.Text.Baseline;
+            public override double Baseline => _element.Text.Baseline;
 
-			public override Size Size => default;
+            public override Size Size => default;
 
-			public override void Draw(DrawingContext drawingContext, Point origin)
-			{
-				_element.Text.Draw(drawingContext, origin);
-			}
-		}
+            public override void Draw(DrawingContext drawingContext, Point origin)
+            {
+                _element.Text.Draw(drawingContext, origin);
+            }
+        }
 
-		private sealed class SpecialCharacterBoxElement : FormattedTextElement
-		{
-			public SpecialCharacterBoxElement(TextLine text) : base(text, 1)
-			{
-			}
+        private sealed class SpecialCharacterBoxElement : FormattedTextElement
+        {
+            public SpecialCharacterBoxElement(TextLine text) : base(text, 1)
+            {
+            }
 
-			public override TextRun CreateTextRun(int startVisualColumn, ITextRunConstructionContext context)
-			{
-				return new SpecialCharacterTextRun(this, TextRunProperties);
-			}
-		}
+            public override TextRun CreateTextRun(int startVisualColumn, ITextRunConstructionContext context)
+            {
+                return new SpecialCharacterTextRun(this, TextRunProperties);
+            }
+        }
 
         internal sealed class SpecialCharacterTextRun : FormattedTextRun
         {
@@ -243,23 +274,23 @@ public override Size Size
                 get
                 {
                     var s = base.Size;
-                    
+
                     return s.WithWidth(s.Width + BoxMargin);
                 }
             }
 
             public override void Draw(DrawingContext drawingContext, Point origin)
             {
-	            var (x, y) = origin;
-	            
-	            var newOrigin = new Point(x + (BoxMargin / 2), y);
-	            
+                var (x, y) = origin;
+
+                var newOrigin = new Point(x + (BoxMargin / 2), y);
+
                 var (width, height) = Size;
-                
+
                 var r = new Rect(x, y, width, height);
-                
+
                 drawingContext.FillRectangle(DarkGrayBrush, r, 2.5f);
-                
+
                 base.Draw(drawingContext, newOrigin);
             }
         }
diff --git a/src/AvaloniaEdit/Rendering/TextView.cs b/src/AvaloniaEdit/Rendering/TextView.cs
index 122d9f36..f8407946 100644
--- a/src/AvaloniaEdit/Rendering/TextView.cs
+++ b/src/AvaloniaEdit/Rendering/TextView.cs
@@ -296,7 +296,7 @@ private void UpdateBuiltinElementGeneratorsFromOptions()
             var options = Options;
 
             //			AddRemoveDefaultElementGeneratorOnDemand(ref newLineElementGenerator, options.ShowEndOfLine);
-            AddRemoveDefaultElementGeneratorOnDemand(ref _singleCharacterElementGenerator, options.ShowBoxForControlCharacters || options.ShowSpaces || options.ShowTabs);
+            AddRemoveDefaultElementGeneratorOnDemand(ref _singleCharacterElementGenerator, options.ShowBoxForControlCharacters || options.ShowSpaces || options.ShowLeadingSpaces || options.ShowTabs);
             AddRemoveDefaultElementGeneratorOnDemand(ref _linkElementGenerator, options.EnableHyperlinks);
             AddRemoveDefaultElementGeneratorOnDemand(ref _mailLinkElementGenerator, options.EnableEmailHyperlinks);
         }
@@ -1776,7 +1776,7 @@ public Point GetVisualPosition(TextViewPosition position, VisualYPosition yPosit
         /// <summary>
         /// Gets a service container used to associate services with the text view.
         /// </summary>
-        internal IServiceContainer Services { get; } = new ServiceContainer();
+        public IServiceContainer Services { get; } = new ServiceContainer();
 
         /// <summary>
         /// Retrieves a service from the text view.
diff --git a/src/AvaloniaEdit/Search/RegexSearchStrategy.cs b/src/AvaloniaEdit/Search/RegexSearchStrategy.cs
index 3d85ac56..34eb4f1f 100644
--- a/src/AvaloniaEdit/Search/RegexSearchStrategy.cs
+++ b/src/AvaloniaEdit/Search/RegexSearchStrategy.cs
@@ -25,56 +25,57 @@
 namespace AvaloniaEdit.Search
 {
     internal class RegexSearchStrategy : ISearchStrategy
-	{
-	    private readonly Regex _searchPattern;
-	    private readonly bool _matchWholeWords;
-		
-		public RegexSearchStrategy(Regex searchPattern, bool matchWholeWords)
-		{
-		    _searchPattern = searchPattern ?? throw new ArgumentNullException(nameof(searchPattern));
-			_matchWholeWords = matchWholeWords;
-		}
-		
-		public IEnumerable<ISearchResult> FindAll(ITextSource document, int offset, int length)
-		{
-			int endOffset = offset + length;
-			foreach (Match result in _searchPattern.Matches(document.Text)) {
-				int resultEndOffset = result.Length + result.Index;
-				if (offset > result.Index || endOffset < resultEndOffset)
-					continue;
-				if (_matchWholeWords && (!IsWordBorder(document, result.Index) || !IsWordBorder(document, resultEndOffset)))
-					continue;
-				yield return new SearchResult { StartOffset = result.Index, Length = result.Length, Data = result };
-			}
-		}
+    {
+        private readonly Regex _searchPattern;
+        private readonly bool _matchWholeWords;
 
-	    private static bool IsWordBorder(ITextSource document, int offset)
-		{
-			return TextUtilities.GetNextCaretPosition(document, offset - 1, LogicalDirection.Forward, CaretPositioningMode.WordBorder) == offset;
-		}
-		
-		public ISearchResult FindNext(ITextSource document, int offset, int length)
-		{
-			return FindAll(document, offset, length).FirstOrDefault();
-		}
-		
-		public bool Equals(ISearchStrategy other)
-		{
-			var strategy = other as RegexSearchStrategy;
-			return strategy != null &&
-				strategy._searchPattern.ToString() == _searchPattern.ToString() &&
-				strategy._searchPattern.Options == _searchPattern.Options &&
-				strategy._searchPattern.RightToLeft == _searchPattern.RightToLeft;
-		}
-	}
+        public RegexSearchStrategy(Regex searchPattern, bool matchWholeWords)
+        {
+            _searchPattern = searchPattern ?? throw new ArgumentNullException(nameof(searchPattern));
+            _matchWholeWords = matchWholeWords;
+        }
 
-    internal class SearchResult : TextSegment, ISearchResult
-	{
-		public Match Data { get; set; }
-		
-		public string ReplaceWith(string replacement)
-		{
-			return Data.Result(replacement);
-		}
-	}
+        public IEnumerable<ISearchResult> FindAll(ITextSource document, int offset, int length)
+        {
+            int endOffset = offset + length;
+            foreach (Match result in _searchPattern.Matches(document.Text))
+            {
+                int resultEndOffset = result.Length + result.Index;
+                if (offset > result.Index || endOffset < resultEndOffset)
+                    continue;
+                if (_matchWholeWords && (!IsWordBorder(document, result.Index) || !IsWordBorder(document, resultEndOffset)))
+                    continue;
+                yield return new SearchResult { StartOffset = result.Index, Length = result.Length, Data = result };
+            }
+        }
+
+        private static bool IsWordBorder(ITextSource document, int offset)
+        {
+            return TextUtilities.GetNextCaretPosition(document, offset - 1, LogicalDirection.Forward, CaretPositioningMode.WordBorder) == offset;
+        }
+
+        public ISearchResult FindNext(ITextSource document, int offset, int length)
+        {
+            return FindAll(document, offset, length).FirstOrDefault();
+        }
+
+        public bool Equals(ISearchStrategy other)
+        {
+            var strategy = other as RegexSearchStrategy;
+            return strategy != null &&
+                strategy._searchPattern.ToString() == _searchPattern.ToString() &&
+                strategy._searchPattern.Options == _searchPattern.Options &&
+                strategy._searchPattern.RightToLeft == _searchPattern.RightToLeft;
+        }
+    }
+
+    public class SearchResult : TextSegment, ISearchResult
+    {
+        public Match Data { get; set; }
+
+        public string ReplaceWith(string replacement)
+        {
+            return Data.Result(replacement);
+        }
+    }
 }
diff --git a/src/AvaloniaEdit/TextEditor.cs b/src/AvaloniaEdit/TextEditor.cs
index aac323a1..ad09b19d 100644
--- a/src/AvaloniaEdit/TextEditor.cs
+++ b/src/AvaloniaEdit/TextEditor.cs
@@ -59,8 +59,6 @@ static TextEditor()
             IsModifiedProperty.Changed.Subscribe(OnIsModifiedChanged);
             ShowLineNumbersProperty.Changed.Subscribe(OnShowLineNumbersChanged);
             LineNumbersForegroundProperty.Changed.Subscribe(OnLineNumbersForegroundChanged);
-            FontFamilyProperty.Changed.Subscribe(OnFontFamilyPropertyChanged);
-            FontSizeProperty.Changed.Subscribe(OnFontSizePropertyChanged);
             SearchResultsBrushProperty.Changed.Subscribe(SearchResultsBrushChangedCallback);
         }
 
@@ -88,7 +86,10 @@ protected TextEditor(TextArea textArea, TextDocument document)
             SetValue(OptionsProperty, textArea.Options);
             SetValue(DocumentProperty, document);
 
+            // 建立属性绑定，确保 TextEditor 的属性变化能自动同步到 TextArea
             textArea[!BackgroundProperty] = this[!BackgroundProperty];
+            textArea[!FontFamilyProperty] = this[!FontFamilyProperty];
+            textArea[!FontSizeProperty] = this[!FontSizeProperty];
         }
 
         #endregion
@@ -598,20 +599,6 @@ private static void OnLineNumbersForegroundChanged(AvaloniaPropertyChangedEventA
             lineNumberMargin?.SetValue(ForegroundProperty, e.NewValue);
         }
 
-        private static void OnFontFamilyPropertyChanged(AvaloniaPropertyChangedEventArgs e)
-        {
-            var editor = e.Sender as TextEditor;
-
-            editor?.TextArea.TextView.SetValue(FontFamilyProperty, e.NewValue);
-        }
-
-        private static void OnFontSizePropertyChanged(AvaloniaPropertyChangedEventArgs e)
-        {
-            var editor = e.Sender as TextEditor;
-
-            editor?.TextArea.TextView.SetValue(FontSizeProperty, e.NewValue);
-        }
-
         private static void SearchResultsBrushChangedCallback(AvaloniaPropertyChangedEventArgs e)
         {
             var editor = e.Sender as TextEditor;
@@ -827,8 +814,8 @@ public void ScrollToHome()
         public void ScrollToHorizontalOffset(double offset)
         {
             ApplyTemplate(); // ensure scrollViewer is created
-            //if (scrollViewer != null)
-            //    scrollViewer.ScrollToHorizontalOffset(offset);
+            if (ScrollViewer != null)
+                ScrollViewer.Offset = ScrollViewer.Offset.WithX(offset);
         }
 
         /// <summary>
@@ -837,8 +824,8 @@ public void ScrollToHorizontalOffset(double offset)
         public void ScrollToVerticalOffset(double offset)
         {
             ApplyTemplate(); // ensure scrollViewer is created
-            //if (scrollViewer != null)
-            //    scrollViewer.ScrollToVerticalOffset(offset);
+            if (ScrollViewer != null)
+                ScrollViewer.Offset = ScrollViewer.Offset.WithY(offset);
         }
 
         /// <summary>
diff --git a/src/AvaloniaEdit/TextEditorOptions.cs b/src/AvaloniaEdit/TextEditorOptions.cs
index 76c609f4..3a26a4a8 100644
--- a/src/AvaloniaEdit/TextEditorOptions.cs
+++ b/src/AvaloniaEdit/TextEditorOptions.cs
@@ -119,6 +119,26 @@ public virtual bool ShowSpaces
             }
         }
 
+        bool showLeadingSpaces;
+
+        /// <summary>
+        /// Gets/Sets whether to show . for leading space.
+        /// </summary>
+        /// <remarks>The default value is <c>false</c>.</remarks>
+        [DefaultValue(false)]
+        public virtual bool ShowLeadingSpaces
+        {
+            get { return showLeadingSpaces; }
+            set
+            {
+                if (showLeadingSpaces != value)
+                {
+                    showLeadingSpaces = value;
+                    OnPropertyChanged(nameof(ShowLeadingSpaces));
+                }
+            }
+        }
+
         /// <summary>
         /// Gets/Sets the char to show when ShowSpaces option is enabled
         /// </summary>