diff --git a/src/Avalonia.Controls/AutoCompleteBox.cs b/src/Avalonia.Controls/AutoCompleteBox.cs
index bfd633c947..b59fd7abde 100644
--- a/src/Avalonia.Controls/AutoCompleteBox.cs
+++ b/src/Avalonia.Controls/AutoCompleteBox.cs
@@ -1405,8 +1405,11 @@ namespace Avalonia.Controls
                     break;
 
                 case Key.Enter:
-                    OnAdapterSelectionComplete(this, new RoutedEventArgs());
-                    e.Handled = true;
+                    if (IsDropDownOpen)
+                    {
+                        OnAdapterSelectionComplete(this, new RoutedEventArgs());
+                        e.Handled = true;
+                    }
                     break;
 
                 default:
diff --git a/src/Avalonia.Controls/Generators/ItemContainerInfo.cs b/src/Avalonia.Controls/Generators/ItemContainerInfo.cs
index 023b108061..31d9a5c02e 100644
--- a/src/Avalonia.Controls/Generators/ItemContainerInfo.cs
+++ b/src/Avalonia.Controls/Generators/ItemContainerInfo.cs
@@ -37,6 +37,6 @@ namespace Avalonia.Controls.Generators
         /// <summary>
         /// Gets the index of the item in the <see cref="ItemsControl.Items"/> collection.
         /// </summary>
-        public int Index { get; internal set; }
+        public int Index { get; set; }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Avalonia.Native/DoubleClickHelper.cs b/src/Avalonia.Native/DoubleClickHelper.cs
new file mode 100644
index 0000000000..7618d6976a
--- /dev/null
+++ b/src/Avalonia.Native/DoubleClickHelper.cs
@@ -0,0 +1,31 @@
+using Avalonia.Platform;
+
+namespace Avalonia.Native
+{
+    internal class DoubleClickHelper
+    {
+        private int _clickCount;
+        private Rect _lastClickRect;
+        private ulong _lastClickTime;
+
+        public bool IsDoubleClick(
+            ulong timestamp,
+            Point p)
+        {
+            var settings = AvaloniaLocator.Current.GetService<IPlatformSettings>();
+            var doubleClickTime = settings.DoubleClickTime.TotalMilliseconds;
+
+            if (!_lastClickRect.Contains(p) || timestamp - _lastClickTime > doubleClickTime)
+            {
+                _clickCount = 0;
+            }
+
+            ++_clickCount;
+            _lastClickTime = timestamp;
+            _lastClickRect = new Rect(p, new Size())
+                .Inflate(new Thickness(settings.DoubleClickSize.Width / 2, settings.DoubleClickSize.Height / 2));
+
+            return _clickCount == 2;
+        }
+    }
+}
diff --git a/src/Avalonia.Native/WindowImpl.cs b/src/Avalonia.Native/WindowImpl.cs
index f60e83efe3..f3b60f07be 100644
--- a/src/Avalonia.Native/WindowImpl.cs
+++ b/src/Avalonia.Native/WindowImpl.cs
@@ -1,4 +1,5 @@
 using System;
+using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Controls.Platform;
 using Avalonia.Input;
@@ -17,6 +18,8 @@ namespace Avalonia.Native
         private readonly AvaloniaNativePlatformOpenGlInterface _glFeature;
         IAvnWindow _native;
         private double _extendTitleBarHeight = -1;
+        private DoubleClickHelper _doubleClickHelper;
+        
 
         internal WindowImpl(IAvaloniaNativeFactory factory, AvaloniaNativePlatformOptions opts,
             AvaloniaNativePlatformOpenGlInterface glFeature) : base(opts, glFeature)
@@ -24,6 +27,8 @@ namespace Avalonia.Native
             _factory = factory;
             _opts = opts;
             _glFeature = glFeature;
+            _doubleClickHelper = new DoubleClickHelper();
+            
             using (var e = new WindowEvents(this))
             {
                 var context = _opts.UseGpu ? glFeature?.MainContext : null;
@@ -118,7 +123,22 @@ namespace Avalonia.Native
 
                     if(visual == null)
                     {
-                        _native.BeginMoveDrag();
+                        if (_doubleClickHelper.IsDoubleClick(e.Timestamp, e.Position))
+                        {
+                            // TOGGLE WINDOW STATE.
+                            if (WindowState == WindowState.Maximized || WindowState == WindowState.FullScreen)
+                            {
+                                WindowState = WindowState.Normal;
+                            }
+                            else
+                            {
+                                WindowState = WindowState.Maximized;
+                            }
+                        }
+                        else
+                        {
+                            _native.BeginMoveDrag();   
+                        }
                     }
                 }
             }
diff --git a/src/Avalonia.Visuals/Matrix.cs b/src/Avalonia.Visuals/Matrix.cs
index 2ccfd43f03..8136f843df 100644
--- a/src/Avalonia.Visuals/Matrix.cs
+++ b/src/Avalonia.Visuals/Matrix.cs
@@ -282,25 +282,44 @@ namespace Avalonia
         }
 
         /// <summary>
-        /// Inverts the Matrix.
+        /// Attempts to invert the Matrix.
         /// </summary>
-        /// <returns>The inverted matrix.</returns>
-        public Matrix Invert()
+        /// <returns>The inverted matrix or <see langword="null"/> when matrix is not invertible.</returns>
+        public bool TryInvert(out Matrix inverted)
         {
             double d = GetDeterminant();
 
             if (MathUtilities.IsZero(d))
             {
-                throw new InvalidOperationException("Transform is not invertible.");
+                inverted = default;
+                
+                return false;
             }
 
-            return new Matrix(
+            inverted = new Matrix(
                 _m22 / d,
                 -_m12 / d,
                 -_m21 / d,
                 _m11 / d,
                 ((_m21 * _m32) - (_m22 * _m31)) / d,
                 ((_m12 * _m31) - (_m11 * _m32)) / d);
+
+            return true;
+        }
+
+        /// <summary>
+        /// Inverts the Matrix.
+        /// </summary>
+        /// <exception cref="InvalidOperationException">Matrix is not invertible.</exception>
+        /// <returns>The inverted matrix.</returns>
+        public Matrix Invert()
+        {
+            if (!TryInvert(out Matrix inverted))
+            {
+                throw new InvalidOperationException("Transform is not invertible.");
+            }
+
+            return inverted;
         }
 
         /// <summary>
diff --git a/src/Avalonia.Visuals/VisualExtensions.cs b/src/Avalonia.Visuals/VisualExtensions.cs
index 6079e5941f..e6523a1469 100644
--- a/src/Avalonia.Visuals/VisualExtensions.cs
+++ b/src/Avalonia.Visuals/VisualExtensions.cs
@@ -50,7 +50,13 @@ namespace Avalonia
             {
                 var thisOffset = GetOffsetFrom(common, from);
                 var thatOffset = GetOffsetFrom(common, to);
-                return -thatOffset * thisOffset;
+
+                if (!thatOffset.TryInvert(out var thatOffsetInverted))
+                {
+                    return null;
+                }
+
+                return thatOffsetInverted * thisOffset;
             }
 
             return null;
diff --git a/src/Skia/Avalonia.Skia/PlatformRenderInterface.cs b/src/Skia/Avalonia.Skia/PlatformRenderInterface.cs
index 72700fb8fd..6d0be9f64d 100644
--- a/src/Skia/Avalonia.Skia/PlatformRenderInterface.cs
+++ b/src/Skia/Avalonia.Skia/PlatformRenderInterface.cs
@@ -3,6 +3,8 @@ using System.Collections;
 using System.Collections.Generic;
 using System.IO; 
 using System.Linq;
+using System.Threading;
+
 using Avalonia.Controls.Platform.Surfaces;
 using Avalonia.Media;
 using Avalonia.OpenGL;
@@ -166,12 +168,13 @@ namespace Avalonia.Skia
             LinearMetrics = true
         };
 
-        private static readonly SKTextBlobBuilder s_textBlobBuilder = new SKTextBlobBuilder();
+        private static readonly ThreadLocal<SKTextBlobBuilder> s_textBlobBuilderThreadLocal = new ThreadLocal<SKTextBlobBuilder>(() => new SKTextBlobBuilder());
 
         /// <inheritdoc />
         public IGlyphRunImpl CreateGlyphRun(GlyphRun glyphRun, out double width)
         {
             var count = glyphRun.GlyphIndices.Length;
+            var textBlobBuilder = s_textBlobBuilderThreadLocal.Value;
 
             var glyphTypeface = (GlyphTypefaceImpl)glyphRun.GlyphTypeface.PlatformImpl;
 
@@ -191,15 +194,15 @@ namespace Avalonia.Skia
             {
                 if (glyphTypeface.IsFixedPitch)
                 {
-                    s_textBlobBuilder.AddRun(glyphRun.GlyphIndices.Buffer.Span, s_font);
+                    textBlobBuilder.AddRun(glyphRun.GlyphIndices.Buffer.Span, s_font);
 
-                    textBlob = s_textBlobBuilder.Build();
+                    textBlob = textBlobBuilder.Build();
 
                     width = glyphTypeface.GetGlyphAdvance(glyphRun.GlyphIndices[0]) * scale * glyphRun.GlyphIndices.Length;
                 }
                 else
                 {
-                    var buffer = s_textBlobBuilder.AllocateHorizontalRun(s_font, count, 0);
+                    var buffer = textBlobBuilder.AllocateHorizontalRun(s_font, count, 0);
 
                     var positions = buffer.GetPositionSpan();
 
@@ -219,12 +222,12 @@ namespace Avalonia.Skia
 
                     buffer.SetGlyphs(glyphRun.GlyphIndices.Buffer.Span);
 
-                    textBlob = s_textBlobBuilder.Build();
+                    textBlob = textBlobBuilder.Build();
                 }
             }
             else
             {
-                var buffer = s_textBlobBuilder.AllocatePositionedRun(s_font, count);
+                var buffer = textBlobBuilder.AllocatePositionedRun(s_font, count);
 
                 var glyphPositions = buffer.GetPositionSpan();
 
@@ -250,7 +253,7 @@ namespace Avalonia.Skia
 
                 width = currentX;
 
-                textBlob = s_textBlobBuilder.Build();
+                textBlob = textBlobBuilder.Build();
             }
 
             return new GlyphRunImpl(textBlob);
diff --git a/tests/Avalonia.Visuals.UnitTests/VisualTests.cs b/tests/Avalonia.Visuals.UnitTests/VisualTests.cs
index 447a68aa69..38131fbfca 100644
--- a/tests/Avalonia.Visuals.UnitTests/VisualTests.cs
+++ b/tests/Avalonia.Visuals.UnitTests/VisualTests.cs
@@ -235,6 +235,25 @@ namespace Avalonia.Visuals.UnitTests
             Assert.Equal(new Point(100, 100), point);
         }
 
+        [Fact]
+        public void TransformToVisual_With_NonInvertible_RenderTransform_Should_Work()
+        {
+            var child = new Decorator
+            {
+                Width = 100,
+                Height = 100,
+                RenderTransform = new ScaleTransform() { ScaleX = 0, ScaleY = 0 }
+            };
+            var root = new TestRoot() { Child = child, Width = 400, Height = 400 };
+
+            root.Measure(Size.Infinity);
+            root.Arrange(new Rect(new Point(), root.DesiredSize));
+
+            var tr = root.TransformToVisual(child);
+
+            Assert.Null(tr);
+        }
+
         [Fact]
         public void Should_Not_Log_Binding_Error_When_Not_Attached_To_Logical_Tree()
         {