addressed review

src/Avalonia.Base/Input/GestureRecognizers/ScrollGestureRecognizer.cs

@@ -178,7 +178,6 @@ namespace Avalonia.Input.GestureRecognizers
                 _inertia = default;
                 _delta = default;
                 _scrolling = false;
-                _velocityTracker?.Dispose();
                 _velocityTracker = null;
                 Target!.RaiseEvent(new ScrollGestureEndedEventArgs(_gestureId));
                 _gestureId = 0;

src/Avalonia.Base/Input/GestureRecognizers/VelocityTracker.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Diagnostics;
-using Avalonia.Utilities;
 
 namespace Avalonia.Input.GestureRecognizers
 {
@@ -59,7 +58,7 @@ namespace Avalonia.Input.GestureRecognizers
     ///
     /// The quality of the velocity estimation will be better if more data points
     /// have been received.
-    internal class VelocityTracker : IDisposable
+    internal class VelocityTracker
     {
         private const int AssumePointerMoveStoppedMilliseconds = 40;
         private const int HistorySize = 20;
@@ -202,11 +201,6 @@ namespace Avalonia.Input.GestureRecognizers
         {
             return GetVelocity().ClampMagnitude(MinFlingVelocity, MaxFlingVelocity);
         }
-
-        public void Dispose()
-        {
-            _sinceLastSample.Stop();
-        }
     }
 
     /// An nth degree polynomial fit to a dataset.

src/Avalonia.Controls/Presenters/ScrollContentPresenter.cs

@@ -621,7 +621,7 @@ namespace Avalonia.Controls.Presenters
 
                 e.Handled = !IsScrollChainingEnabled || offsetChanged;
 
-                if(!e.Handled)
+                if(!e.Handled && !IsScrollChainingEnabled)
                 {
                     // Gesture may cause an overscroll so we mark the event as handled if it did.
                     e.Handled = canXScroll || canYScroll;

src/Avalonia.Controls/Primitives/TextSelectionCanvas.cs

@@ -5,7 +5,6 @@ using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Primitives.PopupPositioning;
 using Avalonia.Input;
 using Avalonia.Interactivity;
-using Avalonia.Layout;
 using Avalonia.Media.TextFormatting;
 using Avalonia.Threading;
 using Avalonia.VisualTree;
@@ -386,7 +385,7 @@ namespace Avalonia.Controls.Primitives
                 if (!_handle1.IsDragging)
                 {
                     var pos = _handle1.SelectionHandleType == SelectionHandleType.Start ? startPoint : endPoint;
-                    if(pos.isRtl != _handle1.IsRtl)
+                    if (pos.isRtl != _handle1.IsRtl)
                         _handle1.NeedsIndicatorUpdate = true;
                     _handle1.IsRtl = pos.isRtl;
                     _handle1.SetTopLeft(ToLayer(pos.position));
@@ -580,7 +579,7 @@ namespace Avalonia.Controls.Primitives
                 ShowHandles = false;
                 CloseFlyout();
             }
-            else if(e.Property == TextBox.SelectionStartProperty || e.Property == TextBox.SelectionEndProperty
+            else if (e.Property == TextBox.SelectionStartProperty || e.Property == TextBox.SelectionEndProperty
                 || e.Property == TextBox.CaretIndexProperty)
             {
                 MoveHandlesToSelection();
@@ -596,42 +595,18 @@ namespace Avalonia.Controls.Primitives
         // Listener to layout changes for presenter.
         private class PresenterVisualListener
         {
-            private List<Visual> _attachedVisuals = new List<Visual>();
             private TextPresenter? _presenter;
-            private object _lock = new object();
 
             public event EventHandler? Invalidated;
 
             public void Attach(TextPresenter presenter)
             {
-                lock (_lock)
-                {
-                    if (_presenter != null)
-                        throw new InvalidOperationException("Listener is already attached to a TextPresenter");
-
-                    _presenter = presenter;
-                    presenter.SizeChanged += Presenter_SizeChanged;
-                    presenter.EffectiveViewportChanged += Visual_EffectiveViewportChanged;
-
-
-                    void AttachViewportHandler(Visual visual)
-                    {
-                        if (visual is Layoutable layoutable)
-                        {
-                            layoutable.EffectiveViewportChanged += Visual_EffectiveViewportChanged;
-                        }
-
-                        _attachedVisuals.Add(visual);
-                    }
+                if (_presenter != null)
+                    throw new InvalidOperationException("Listener is already attached to a TextPresenter");
 
-                    var visualParent = presenter.VisualParent;
-                    while (visualParent != null)
-                    {
-                        AttachViewportHandler(visualParent);
-
-                        visualParent = visualParent.VisualParent;
-                    }
-                }
+                _presenter = presenter;
+                presenter.SizeChanged += Presenter_SizeChanged;
+                presenter.EffectiveViewportChanged += Visual_EffectiveViewportChanged;
             }
 
             private void Visual_EffectiveViewportChanged(object? sender, Layout.EffectiveViewportChangedEventArgs e)
@@ -646,25 +621,13 @@ namespace Avalonia.Controls.Primitives
 
             public void Detach()
             {
-                lock (_lock)
+                if (_presenter is { } presenter)
                 {
-                    if (_presenter is { } presenter)
-                    {
-                        presenter.SizeChanged -= Presenter_SizeChanged;
-                        presenter.EffectiveViewportChanged -= Visual_EffectiveViewportChanged;
-                    }
-
-                    foreach (var visual in _attachedVisuals)
-                    {
-                        if (visual is Layoutable layoutable)
-                        {
-                            layoutable.EffectiveViewportChanged -= Visual_EffectiveViewportChanged;
-                        }
-                    }
-
-                    _presenter = null;
-                    _attachedVisuals.Clear();
+                    presenter.SizeChanged -= Presenter_SizeChanged;
+                    presenter.EffectiveViewportChanged -= Visual_EffectiveViewportChanged;
                 }
+
+                _presenter = null;
             }
 
             private void OnInvalidated()

src/Avalonia.Controls/Primitives/TextSelectionHandle.cs

@@ -1,9 +1,7 @@
 using System;
-using System.Drawing;
 using Avalonia.Controls.Metadata;
 using Avalonia.Input;
 using Avalonia.Interactivity;
-using Avalonia.Media;
 
 namespace Avalonia.Controls.Primitives
 {
@@ -252,17 +250,17 @@ namespace Avalonia.Controls.Primitives
 
         private void UpdateHandleClasses()
         {
-            Classes.Remove("caret");
-            Classes.Remove("start");
-            Classes.Remove("end");
+            PseudoClasses.Remove(":caret");
+            PseudoClasses.Remove(":start");
+            PseudoClasses.Remove(":end");
 
-            Classes.Add(SelectionHandleType switch
+            PseudoClasses.Add(":" + (SelectionHandleType switch
             {
                 SelectionHandleType.Caret => "caret",
                 SelectionHandleType.Start => IsRtl ? "end" : "start",
                 SelectionHandleType.End => IsRtl ? "start" : "end",
                 _ => throw new NotImplementedException(),
-            });
+            }));
             InvalidateVisual();
         }
     }

src/Avalonia.Controls/TextBox.cs

@@ -35,7 +35,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// The radius for touch input. Used to determine if selection should change from moving a touch pointer.
         /// </summary>
-        private readonly static int s_touchRadius = (int)((AvaloniaLocator.Current?.GetService<IPlatformSettings>()?.GetTapSize(PointerType.Touch).Height ?? 10) / 2) + 5;
+        private readonly Lazy<int> _touchRadius = new(() => (int)((AvaloniaLocator.Current?.GetService<IPlatformSettings>()?.GetTapSize(PointerType.Touch).Height ?? 10) / 2) + 5);
 
         /// <summary>
         /// Gets a platform-specific <see cref="KeyGesture"/> for the Cut action
@@ -1735,7 +1735,7 @@ namespace Avalonia.Controls
         {
             base.OnTapped(e);
 
-            if(e.Pointer.Type != PointerType.Mouse)
+            if (e.Pointer.Type != PointerType.Mouse)
             {
                 _presenter?.EnsureTextSelectionLayer();
                 _presenter?.TextSelectionHandleCanvas?.Show();
@@ -1815,18 +1815,13 @@ namespace Avalonia.Controls
 
                     if (_isDoubleTapped)
                     {
-                        var oldCaret = _presenter.CaretIndex;
                         _presenter.MoveCaretToPoint(_lastPoint);
                         var caretIndex = _presenter.CaretIndex;
 
-                        if(Math.Abs(oldCaret - caretIndex) > 3)
-                        {
-                            return;
-                        }
                         var selectionStart = SelectionStart;
                         var selectionEnd = SelectionEnd;
 
-                        SelectWord(text, caretIndex, caretIndex, caretIndex);
+                        SelectWord(text, caretIndex, selectionStart, selectionEnd);
                         _presenter?.EnsureTextSelectionLayer();
                         _presenter?.TextSelectionHandleCanvas?.Show();
                     }
@@ -1957,7 +1952,7 @@ namespace Avalonia.Controls
                     if (!_isInTouchCaretMode)
                     {
 
-                        var touchRect = new Rect(_lastPoint.X, _lastPoint.Y, 0, 0).Inflate(s_touchRadius);
+                        var touchRect = new Rect(_lastPoint.X, _lastPoint.Y, 0, 0).Inflate(_touchRadius.Value);
                         var isInRect = touchRect.X < point.X &&
                            touchRect.Y < point.Y &&
                            touchRect.Right > point.X &&

src/Avalonia.Themes.Fluent/Controls/TextSelectionHandle.xaml

@@ -97,21 +97,21 @@
         </ControlTemplate>
       </Setter.Value>
     </Setter>
-    <Style Selector="^.caret /template/ Image#PART_HandlePathIcon">
+    <Style Selector="^:caret /template/ Image#PART_HandlePathIcon">
       <Setter Property="Source" Value="{DynamicResource TextCaretHandleDrawing}" />
     </Style>
-    <Style Selector="^.start /template/ Image#PART_HandlePathIcon">
+    <Style Selector="^:start /template/ Image#PART_HandlePathIcon">
       <Setter Property="RenderTransform">
         <ScaleTransform ScaleX="-1" ScaleY="1"/>
       </Setter>
     </Style>
-    <Style Selector="^.caret /template/ Border#PART_Indicator">
+    <Style Selector="^:caret /template/ Border#PART_Indicator">
       <Setter Property="HorizontalAlignment" Value="Center" />
     </Style>
-    <Style Selector="^.end /template/ Border#PART_Indicator">
+    <Style Selector="^:end /template/ Border#PART_Indicator">
       <Setter Property="HorizontalAlignment" Value="Left" />
     </Style>
-    <Style Selector="^.start /template/ Border#PART_Indicator">
+    <Style Selector="^:start /template/ Border#PART_Indicator">
       <Setter Property="HorizontalAlignment" Value="Right" />
     </Style>
   </ControlTheme>

src/Avalonia.Themes.Simple/Controls/TextSelectionHandle.xaml

@@ -85,21 +85,21 @@
         </ControlTemplate>
       </Setter.Value>
     </Setter>
-    <Style Selector="^.caret /template/ Image#PART_HandlePathIcon">
+    <Style Selector="^:caret /template/ Image#PART_HandlePathIcon">
       <Setter Property="Source" Value="{DynamicResource TextCaretHandleDrawing}" />
     </Style>
-    <Style Selector="^.start /template/ Image#PART_HandlePathIcon">
+    <Style Selector="^:start /template/ Image#PART_HandlePathIcon">
       <Setter Property="RenderTransform">
         <ScaleTransform ScaleX="-1" ScaleY="1"/>
       </Setter>
     </Style>
-    <Style Selector="^.caret /template/ Border#PART_Indicator">
+    <Style Selector="^:caret /template/ Border#PART_Indicator">
       <Setter Property="HorizontalAlignment" Value="Center" />
     </Style>
-    <Style Selector="^.end /template/ Border#PART_Indicator">
+    <Style Selector="^:end /template/ Border#PART_Indicator">
       <Setter Property="HorizontalAlignment" Value="Left" />
     </Style>
-    <Style Selector="^.start /template/ Border#PART_Indicator">
+    <Style Selector="^:start /template/ Border#PART_Indicator">
       <Setter Property="HorizontalAlignment" Value="Right" />
     </Style>
   </ControlTheme>