diff --git a/samples/ControlCatalog/App.xaml b/samples/ControlCatalog/App.xaml
index 227b31bf20..d0e1bd885e 100644
--- a/samples/ControlCatalog/App.xaml
+++ b/samples/ControlCatalog/App.xaml
@@ -3,6 +3,7 @@
              xmlns:vm="using:ControlCatalog.ViewModels"
              x:DataType="vm:ApplicationViewModel"
              x:CompileBindings="True"
+             Name="Avalonia ControlCatalog"
              x:Class="ControlCatalog.App">
   <Application.Styles>
     <Style Selector="TextBlock.h1, TextBlock.h2, TextBlock.h3">
diff --git a/samples/ControlCatalog/Models/Person.cs b/samples/ControlCatalog/Models/Person.cs
index 47f41bc584..cd70fa3959 100644
--- a/samples/ControlCatalog/Models/Person.cs
+++ b/samples/ControlCatalog/Models/Person.cs
@@ -16,6 +16,7 @@ namespace ControlCatalog.Models
         string _firstName;
         string _lastName;
         bool _isBanned;
+        private int _age;
 
         public string FirstName
         {
@@ -59,6 +60,20 @@ namespace ControlCatalog.Models
             }
         }
 
+        
+        /// <summary>
+        ///    Gets or sets the age of the person
+        /// </summary>
+        public int Age
+        {
+            get => _age;
+            set
+            {
+                _age = value;
+                OnPropertyChanged(nameof(Age));
+            }
+        }
+
         Dictionary<string, List<string>> _errorLookup = new Dictionary<string, List<string>>();
 
         void SetError(string propertyName, string error)
diff --git a/samples/ControlCatalog/Pages/DataGridPage.xaml b/samples/ControlCatalog/Pages/DataGridPage.xaml
index 63e873d9b5..f7e3cf2441 100644
--- a/samples/ControlCatalog/Pages/DataGridPage.xaml
+++ b/samples/ControlCatalog/Pages/DataGridPage.xaml
@@ -64,6 +64,18 @@
               <DataGridTextColumn Header="First Name" Binding="{Binding FirstName}" Width="2*" FontSize="{Binding #FontSizeSlider.Value, Mode=OneWay}" />
               <DataGridTextColumn Header="Last" Binding="{Binding LastName}" Width="2*" FontSize="{Binding #FontSizeSlider.Value, Mode=OneWay}" />
               <DataGridCheckBoxColumn Header="Is Banned" Binding="{Binding IsBanned}" Width="*" IsThreeState="{Binding #IsThreeStateCheckBox.IsChecked, Mode=OneWay}" />
+              <DataGridTemplateColumn Header="Age" >
+                <DataGridTemplateColumn.CellTemplate>
+                  <DataTemplate DataType="local:Person">
+                    <TextBlock Text="{Binding Age, StringFormat='{}{0} years'}" VerticalAlignment="Center" HorizontalAlignment="Center" />
+                  </DataTemplate>
+                </DataGridTemplateColumn.CellTemplate>
+                <DataGridTemplateColumn.CellEditingTemplate>
+                  <DataTemplate DataType="local:Person">
+                    <NumericUpDown Value="{Binding Age}" FormatString="N0" HorizontalAlignment="Stretch" Minimum="0" Maximum="120" TemplateApplied="NumericUpDown_OnTemplateApplied" />
+                  </DataTemplate>
+                </DataGridTemplateColumn.CellEditingTemplate>
+              </DataGridTemplateColumn>
             </DataGrid.Columns>
           </DataGrid>
           <Button Grid.Row="1" Name="btnAdd" Margin="12,0,12,12" Content="Add" HorizontalAlignment="Right" />
diff --git a/samples/ControlCatalog/Pages/DataGridPage.xaml.cs b/samples/ControlCatalog/Pages/DataGridPage.xaml.cs
index dc5cc49a90..c010d38eac 100644
--- a/samples/ControlCatalog/Pages/DataGridPage.xaml.cs
+++ b/samples/ControlCatalog/Pages/DataGridPage.xaml.cs
@@ -6,7 +6,9 @@ using Avalonia.Controls;
 using Avalonia.Markup.Xaml;
 using ControlCatalog.Models;
 using Avalonia.Collections;
+using Avalonia.Controls.Primitives;
 using Avalonia.Data;
+using Avalonia.Threading;
 
 namespace ControlCatalog.Pages
 {
@@ -48,9 +50,9 @@ namespace ControlCatalog.Pages
 
             var items = new List<Person>
             {
-                new Person { FirstName = "John", LastName = "Doe" },
-                new Person { FirstName = "Elizabeth", LastName = "Thomas", IsBanned = true },
-                new Person { FirstName = "Zack", LastName = "Ward" }
+                new Person { FirstName = "John", LastName = "Doe" , Age = 30},
+                new Person { FirstName = "Elizabeth", LastName = "Thomas", IsBanned = true , Age = 40 },
+                new Person { FirstName = "Zack", LastName = "Ward" , Age = 50 }
             };
             var collectionView3 = new DataGridCollectionView(items);
 
@@ -84,5 +86,19 @@ namespace ControlCatalog.Pages
                 return Comparer.Default.Compare(x, y);
             }
         }
+
+        private void NumericUpDown_OnTemplateApplied(object sender, TemplateAppliedEventArgs e)
+        {
+            // We want to focus the TextBox of the NumericUpDown. To do so we search for this control when the template
+            // is applied, but we postpone the action until the control is actually loaded. 
+            if (e.NameScope.Find<TextBox>("PART_TextBox") is {} textBox)
+            {
+                Dispatcher.UIThread.InvokeAsync(() =>
+                {
+                    textBox.Focus();
+                    textBox.SelectAll();
+                }, DispatcherPriority.Loaded);
+            }
+        }
     }
 }
diff --git a/src/Avalonia.Animation/Animatable.cs b/src/Avalonia.Animation/Animatable.cs
index 4811028f85..50fc5ac73b 100644
--- a/src/Avalonia.Animation/Animatable.cs
+++ b/src/Avalonia.Animation/Animatable.cs
@@ -157,7 +157,7 @@ namespace Avalonia.Animation
                             state.Instance?.Dispose();
                             state.Instance = transition.Apply(
                                 this,
-                                Clock ?? AvaloniaLocator.Current.GetService<IGlobalClock>(),
+                                Clock ?? AvaloniaLocator.Current.GetRequiredService<IGlobalClock>(),
                                 oldValue,
                                 newValue);
                             return;
@@ -169,7 +169,7 @@ namespace Avalonia.Animation
             base.OnPropertyChangedCore(change);
         }
 
-        private void TransitionsCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
+        private void TransitionsCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
         {
             if (!_transitionsEnabled)
             {
@@ -179,14 +179,14 @@ namespace Avalonia.Animation
             switch (e.Action)
             {
                 case NotifyCollectionChangedAction.Add:
-                    AddTransitions(e.NewItems);
+                    AddTransitions(e.NewItems!);
                     break;
                 case NotifyCollectionChangedAction.Remove:
-                    RemoveTransitions(e.OldItems);
+                    RemoveTransitions(e.OldItems!);
                     break;
                 case NotifyCollectionChangedAction.Replace:
-                    RemoveTransitions(e.OldItems);
-                    AddTransitions(e.NewItems);
+                    RemoveTransitions(e.OldItems!);
+                    AddTransitions(e.NewItems!);
                     break;
                 case NotifyCollectionChangedAction.Reset:
                     throw new NotSupportedException("Transitions collection cannot be reset.");
@@ -204,7 +204,7 @@ namespace Avalonia.Animation
 
             for (var i = 0; i < items.Count; ++i)
             {
-                var t = (ITransition)items[i];
+                var t = (ITransition)items[i]!;
 
                 _transitionState.Add(t, new TransitionState
                 {
@@ -222,7 +222,7 @@ namespace Avalonia.Animation
 
             for (var i = 0; i < items.Count; ++i)
             {
-                var t = (ITransition)items[i];
+                var t = (ITransition)items[i]!;
 
                 if (_transitionState.TryGetValue(t, out var state))
                 {
diff --git a/src/Avalonia.Animation/Animation.cs b/src/Avalonia.Animation/Animation.cs
index a4515db514..03b2d17e44 100644
--- a/src/Avalonia.Animation/Animation.cs
+++ b/src/Avalonia.Animation/Animation.cs
@@ -203,7 +203,7 @@ namespace Avalonia.Animation
         /// </summary>
         /// <param name="setter">The animation setter.</param>
         /// <returns>The property animator type.</returns>
-        public static Type GetAnimator(IAnimationSetter setter)
+        public static Type? GetAnimator(IAnimationSetter setter)
         {
             if (s_animators.TryGetValue(setter, out var type))
             {
@@ -254,7 +254,7 @@ namespace Avalonia.Animation
             Animators.Insert(0, (condition, typeof(TAnimator)));
         }
 
-        private static Type GetAnimatorType(AvaloniaProperty property)
+        private static Type? GetAnimatorType(AvaloniaProperty property)
         {
             foreach (var (condition, type) in Animators)
             {
@@ -276,6 +276,11 @@ namespace Avalonia.Animation
             {
                 foreach (var setter in keyframe.Setters)
                 {
+                    if (setter.Property is null)
+                    {
+                        throw new InvalidOperationException("No Setter property assigned.");
+                    }
+
                     var handler = Animation.GetAnimator(setter) ?? GetAnimatorType(setter.Property);
 
                     if (handler == null)
@@ -305,7 +310,7 @@ namespace Avalonia.Animation
 
             foreach (var (handlerType, property) in handlerList)
             {
-                var newInstance = (IAnimator)Activator.CreateInstance(handlerType);
+                var newInstance = (IAnimator)Activator.CreateInstance(handlerType)!;
                 newInstance.Property = property;
                 newAnimatorInstances.Add(newInstance);
             }
@@ -321,32 +326,43 @@ namespace Avalonia.Animation
         }
 
         /// <inheritdoc/>
-        public IDisposable Apply(Animatable control, IClock clock, IObservable<bool> match, Action onComplete)
+        public IDisposable Apply(Animatable control, IClock? clock, IObservable<bool> match, Action? onComplete)
         {
             var (animators, subscriptions) = InterpretKeyframes(control);
             if (animators.Count == 1)
             {
-                subscriptions.Add(animators[0].Apply(this, control, clock, match, onComplete));
+                var subscription = animators[0].Apply(this, control, clock, match, onComplete);
+                
+                if (subscription is not null)
+                {
+                    subscriptions.Add(subscription);
+                }
             }
             else
             {
                 var completionTasks = onComplete != null ? new List<Task>() : null;
                 foreach (IAnimator animator in animators)
                 {
-                    Action animatorOnComplete = null;
+                    Action? animatorOnComplete = null;
                     if (onComplete != null)
                     {
-                        var tcs = new TaskCompletionSource<object>();
+                        var tcs = new TaskCompletionSource<object?>();
                         animatorOnComplete = () => tcs.SetResult(null);
-                        completionTasks.Add(tcs.Task);
+                        completionTasks!.Add(tcs.Task);
+                    }
+
+                    var subscription = animator.Apply(this, control, clock, match, animatorOnComplete);
+
+                    if (subscription is not null)
+                    {
+                        subscriptions.Add(subscription);
                     }
-                    subscriptions.Add(animator.Apply(this, control, clock, match, animatorOnComplete));
                 }
 
                 if (onComplete != null)
                 {
-                    Task.WhenAll(completionTasks).ContinueWith(
-                        (_, state) => ((Action)state).Invoke(),
+                    Task.WhenAll(completionTasks!).ContinueWith(
+                        (_, state) => ((Action)state!).Invoke(),
                         onComplete);
                 }
             }
@@ -354,25 +370,25 @@ namespace Avalonia.Animation
         }
 
         /// <inheritdoc/>
-        public Task RunAsync(Animatable control, IClock clock = null)
+        public Task RunAsync(Animatable control, IClock? clock = null)
         {
             return RunAsync(control, clock, default);
         }
 
         /// <inheritdoc/>
-        public Task RunAsync(Animatable control, IClock clock = null, CancellationToken cancellationToken = default)
+        public Task RunAsync(Animatable control, IClock? clock = null, CancellationToken cancellationToken = default)
         {
             if (cancellationToken.IsCancellationRequested)
             {
                 return Task.CompletedTask;
             }
 
-            var run = new TaskCompletionSource<object>();
+            var run = new TaskCompletionSource<object?>();
 
             if (this.IterationCount == IterationCount.Infinite)
                 run.SetException(new InvalidOperationException("Looping animations must not use the Run method."));
 
-            IDisposable subscriptions = null, cancellation = null;
+            IDisposable? subscriptions = null, cancellation = null;
             subscriptions = this.Apply(control, clock, Observable.Return(true), () =>
             {
                 run.TrySetResult(null);
diff --git a/src/Avalonia.Animation/AnimationInstance`1.cs b/src/Avalonia.Animation/AnimationInstance`1.cs
index cf79640150..52cd4b324f 100644
--- a/src/Avalonia.Animation/AnimationInstance`1.cs
+++ b/src/Avalonia.Animation/AnimationInstance`1.cs
@@ -31,15 +31,15 @@ namespace Avalonia.Animation
         private TimeSpan _initialDelay;
         private TimeSpan _iterationDelay;
         private TimeSpan _duration;
-        private Easings.Easing _easeFunc;
-        private Action _onCompleteAction;
+        private Easings.Easing? _easeFunc;
+        private Action? _onCompleteAction;
         private Func<double, T, T> _interpolator;
-        private IDisposable _timerSub;
+        private IDisposable? _timerSub;
         private readonly IClock _baseClock;
-        private IClock _clock;
-        private EventHandler<AvaloniaPropertyChangedEventArgs> _propertyChangedDelegate;
+        private IClock? _clock;
+        private EventHandler<AvaloniaPropertyChangedEventArgs>? _propertyChangedDelegate;
 
-        public AnimationInstance(Animation animation, Animatable control, Animator<T> animator, IClock baseClock, Action OnComplete, Func<double, T, T> Interpolator)
+        public AnimationInstance(Animation animation, Animatable control, Animator<T> animator, IClock baseClock, Action? OnComplete, Func<double, T, T> Interpolator)
         {
             _animator = animator;
             _animation = animation;
@@ -47,6 +47,9 @@ namespace Avalonia.Animation
             _onCompleteAction = OnComplete;
             _interpolator = Interpolator;
             _baseClock = baseClock;
+            _lastInterpValue = default!;
+            _firstKFValue = default!;
+            _neutralValue = default!;
             FetchProperties();
         }
 
@@ -82,7 +85,7 @@ namespace Avalonia.Animation
 
             _targetControl.PropertyChanged -= _propertyChangedDelegate;
             _timerSub?.Dispose();
-            _clock.PlayState = PlayState.Stop;
+            _clock!.PlayState = PlayState.Stop;
         }
 
         protected override void Subscribed()
@@ -108,6 +111,8 @@ namespace Avalonia.Animation
 
         private void ApplyFinalFill()
         {
+            if (_animator.Property is null)
+                throw new InvalidOperationException("Animator has no property specified.");
             if (_fillMode == FillMode.Forward || _fillMode == FillMode.Both)
                 _targetControl.SetValue(_animator.Property, _lastInterpValue, BindingPriority.LocalValue);
         }
@@ -130,12 +135,12 @@ namespace Avalonia.Animation
 
         private void DoPlayStates()
         {
-            if (_clock.PlayState == PlayState.Stop || _baseClock.PlayState == PlayState.Stop)
+            if (_clock!.PlayState == PlayState.Stop || _baseClock.PlayState == PlayState.Stop)
                 DoComplete();
 
             if (!_gotFirstKFValue)
             {
-                _firstKFValue = (T)_animator.First().Value;
+                _firstKFValue = (T)_animator.First().Value!;
                 _gotFirstKFValue = true;
             }
         }
@@ -169,7 +174,7 @@ namespace Avalonia.Animation
                 // and snap the last iteration value to exact values.
                 if ((_currentIteration + 1) > _iterationCount)
                 {
-                    var easedTime = _easeFunc.Ease(_playbackReversed ? 0.0 : 1.0);
+                    var easedTime = _easeFunc!.Ease(_playbackReversed ? 0.0 : 1.0);
                     _lastInterpValue = _interpolator(easedTime, _neutralValue);
                     DoComplete();
                 }
@@ -203,7 +208,7 @@ namespace Avalonia.Animation
                         normalizedTime = 1 - normalizedTime;
 
                     // Ease and interpolate
-                    var easedTime = _easeFunc.Ease(normalizedTime);
+                    var easedTime = _easeFunc!.Ease(normalizedTime);
                     _lastInterpValue = _interpolator(easedTime, _neutralValue);
 
                     PublishNext(_lastInterpValue);
@@ -223,14 +228,14 @@ namespace Avalonia.Animation
 
         private void UpdateNeutralValue()
         {
-            var property = _animator.Property;
+            var property = _animator.Property ?? throw new InvalidOperationException("Animator has no property specified.");
             var baseValue = _targetControl.GetBaseValue(property, BindingPriority.LocalValue);
 
             _neutralValue = baseValue != AvaloniaProperty.UnsetValue ?
-                (T)baseValue : (T)_targetControl.GetValue(property);
+                (T)baseValue! : (T)_targetControl.GetValue(property)!;
         }
 
-        private void ControlPropertyChanged(object sender, AvaloniaPropertyChangedEventArgs e)
+        private void ControlPropertyChanged(object? sender, AvaloniaPropertyChangedEventArgs e)
         {
             if (e.Property == _animator.Property && e.Priority > BindingPriority.Animation)
             {
diff --git a/src/Avalonia.Animation/AnimatorKeyFrame.cs b/src/Avalonia.Animation/AnimatorKeyFrame.cs
index f6a0c12be4..8af31f2948 100644
--- a/src/Avalonia.Animation/AnimatorKeyFrame.cs
+++ b/src/Avalonia.Animation/AnimatorKeyFrame.cs
@@ -12,22 +12,22 @@ namespace Avalonia.Animation
     /// </summary>
     public class AnimatorKeyFrame : AvaloniaObject
     {
-        public static readonly DirectProperty<AnimatorKeyFrame, object> ValueProperty =
-            AvaloniaProperty.RegisterDirect<AnimatorKeyFrame, object>(nameof(Value), k => k.Value, (k, v) => k.Value = v);
+        public static readonly DirectProperty<AnimatorKeyFrame, object?> ValueProperty =
+            AvaloniaProperty.RegisterDirect<AnimatorKeyFrame, object?>(nameof(Value), k => k.Value, (k, v) => k.Value = v);
 
         public AnimatorKeyFrame()
         {
 
         }
 
-        public AnimatorKeyFrame(Type animatorType, Cue cue)
+        public AnimatorKeyFrame(Type? animatorType, Cue cue)
         {
             AnimatorType = animatorType;
             Cue = cue;
             KeySpline = null;
         }
 
-        public AnimatorKeyFrame(Type animatorType, Cue cue, KeySpline keySpline)
+        public AnimatorKeyFrame(Type? animatorType, Cue cue, KeySpline? keySpline)
         {
             AnimatorType = animatorType;
             Cue = cue;
@@ -35,14 +35,14 @@ namespace Avalonia.Animation
         }
 
         internal bool isNeutral;
-        public Type AnimatorType { get; }
+        public Type? AnimatorType { get; }
         public Cue Cue { get; }
-        public KeySpline KeySpline { get; }
-        public AvaloniaProperty Property { get; private set; }
+        public KeySpline? KeySpline { get; }
+        public AvaloniaProperty? Property { get; private set; }
 
-        private object _value;
+        private object? _value;
 
-        public object Value
+        public object? Value
         {
             get => _value;
             set => SetAndRaise(ValueProperty, ref _value, value);
@@ -80,7 +80,7 @@ namespace Avalonia.Animation
                 throw new InvalidCastException($"KeyFrame value doesnt match property type.");
             }
 
-            return (T)typeConv.ConvertTo(Value, typeof(T));
+            return (T)typeConv.ConvertTo(Value, typeof(T))!;
         }
     }
 }
diff --git a/src/Avalonia.Animation/Animators/Animator`1.cs b/src/Avalonia.Animation/Animators/Animator`1.cs
index 23afa76bf6..248ca61c1d 100644
--- a/src/Avalonia.Animation/Animators/Animator`1.cs
+++ b/src/Avalonia.Animation/Animators/Animator`1.cs
@@ -24,7 +24,7 @@ namespace Avalonia.Animation.Animators
         /// <summary>
         /// Gets or sets the target property for the keyframe.
         /// </summary>
-        public AvaloniaProperty Property { get; set; }
+        public AvaloniaProperty? Property { get; set; }
 
         public Animator()
         {
@@ -33,7 +33,7 @@ namespace Avalonia.Animation.Animators
         }
 
         /// <inheritdoc/>
-        public virtual IDisposable Apply(Animation animation, Animatable control, IClock clock, IObservable<bool> match, Action onComplete)
+        public virtual IDisposable? Apply(Animation animation, Animatable control, IClock? clock, IObservable<bool> match, Action? onComplete)
         {
             if (!_isVerifiedAndConverted)
                 VerifyConvertKeyFrames();
@@ -106,13 +106,16 @@ namespace Avalonia.Animation.Animators
 
         public virtual IDisposable BindAnimation(Animatable control, IObservable<T> instance)
         {
+            if (Property is null)
+                throw new InvalidOperationException("Animator has no property specified.");
+
             return control.Bind((AvaloniaProperty<T>)Property, instance, BindingPriority.Animation);
         }
 
         /// <summary>
         /// Runs the KeyFrames Animation.
         /// </summary>
-        internal IDisposable Run(Animation animation, Animatable control, IClock clock, Action onComplete)
+        internal IDisposable Run(Animation animation, Animatable control, IClock? clock, Action? onComplete)
         {
             var instance = new AnimationInstance<T>(
                 animation,
diff --git a/src/Avalonia.Animation/Avalonia.Animation.csproj b/src/Avalonia.Animation/Avalonia.Animation.csproj
index 465b922b72..d81d14bbff 100644
--- a/src/Avalonia.Animation/Avalonia.Animation.csproj
+++ b/src/Avalonia.Animation/Avalonia.Animation.csproj
@@ -2,9 +2,13 @@
   <PropertyGroup>
     <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
   </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="..\Avalonia.Base\Metadata\NullableAttributes.cs" Link="NullableAttributes.cs" />
+  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\Avalonia.Base\Avalonia.Base.csproj" />
   </ItemGroup>
   <Import Project="..\..\build\Rx.props" />
   <Import Project="..\..\build\ApiDiff.props" />
+  <Import Project="..\..\build\NullableEnable.props" />
 </Project>
diff --git a/src/Avalonia.Animation/Clock.cs b/src/Avalonia.Animation/Clock.cs
index 5c2b7ce0dd..5afd2ae705 100644
--- a/src/Avalonia.Animation/Clock.cs
+++ b/src/Avalonia.Animation/Clock.cs
@@ -4,7 +4,7 @@ namespace Avalonia.Animation
 {
     public class Clock : ClockBase
     {
-        public static IClock GlobalClock => AvaloniaLocator.Current.GetService<IGlobalClock>();
+        public static IClock GlobalClock => AvaloniaLocator.Current.GetRequiredService<IGlobalClock>();
 
         private readonly IDisposable _parentSubscription;
 
diff --git a/src/Avalonia.Animation/Cue.cs b/src/Avalonia.Animation/Cue.cs
index 7da7a9382b..6578148b07 100644
--- a/src/Avalonia.Animation/Cue.cs
+++ b/src/Avalonia.Animation/Cue.cs
@@ -30,7 +30,7 @@ namespace Avalonia.Animation
         /// <summary>
         /// Parses a string to a <see cref="Cue"/> object.
         /// </summary>
-        public static Cue Parse(string value, CultureInfo culture)
+        public static Cue Parse(string value, CultureInfo? culture)
         {
             string v = value;
 
@@ -72,14 +72,14 @@ namespace Avalonia.Animation
 
     public class CueTypeConverter : TypeConverter
     {
-        public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
+        public override bool CanConvertFrom(ITypeDescriptorContext? context, Type sourceType)
         {
             return sourceType == typeof(string);
         }
 
-        public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
+        public override object ConvertFrom(ITypeDescriptorContext? context, CultureInfo? culture, object value)
         {
             return Cue.Parse((string)value, culture);
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Avalonia.Animation/DisposeAnimationInstanceSubject.cs b/src/Avalonia.Animation/DisposeAnimationInstanceSubject.cs
index 696f43d006..7283eaeedf 100644
--- a/src/Avalonia.Animation/DisposeAnimationInstanceSubject.cs
+++ b/src/Avalonia.Animation/DisposeAnimationInstanceSubject.cs
@@ -8,15 +8,15 @@ namespace Avalonia.Animation
     /// </summary>
     internal class DisposeAnimationInstanceSubject<T> : IObserver<bool>, IDisposable
     {
-        private IDisposable _lastInstance;
+        private IDisposable? _lastInstance;
         private bool _lastMatch;
         private Animator<T> _animator;
         private Animation _animation;
         private Animatable _control;
-        private Action _onComplete;
-        private IClock _clock;
+        private Action? _onComplete;
+        private IClock? _clock;
 
-        public DisposeAnimationInstanceSubject(Animator<T> animator, Animation animation, Animatable control, IClock clock, Action onComplete)
+        public DisposeAnimationInstanceSubject(Animator<T> animator, Animation animation, Animatable control, IClock? clock, Action? onComplete)
         {
             this._animator = animator;
             this._animation = animation;
diff --git a/src/Avalonia.Animation/Easing/Easing.cs b/src/Avalonia.Animation/Easing/Easing.cs
index e006459652..2f4b93dab1 100644
--- a/src/Avalonia.Animation/Easing/Easing.cs
+++ b/src/Avalonia.Animation/Easing/Easing.cs
@@ -15,7 +15,7 @@ namespace Avalonia.Animation.Easings
         /// <inheritdoc/>
         public abstract double Ease(double progress);
 
-        static Dictionary<string, Type> _easingTypes;
+        static Dictionary<string, Type>? _easingTypes;
 
         static readonly Type s_thisType = typeof(Easing);
 
@@ -48,7 +48,7 @@ namespace Avalonia.Animation.Easings
             if (_easingTypes.ContainsKey(e))
             {
                 var type = _easingTypes[e];
-                return (Easing)Activator.CreateInstance(type);
+                return (Easing)Activator.CreateInstance(type)!;
             }
             else
             {
diff --git a/src/Avalonia.Animation/Easing/EasingTypeConverter.cs b/src/Avalonia.Animation/Easing/EasingTypeConverter.cs
index 6613f6d393..3d67d54a6f 100644
--- a/src/Avalonia.Animation/Easing/EasingTypeConverter.cs
+++ b/src/Avalonia.Animation/Easing/EasingTypeConverter.cs
@@ -6,12 +6,12 @@ namespace Avalonia.Animation.Easings
 {
     public class EasingTypeConverter : TypeConverter
     {
-        public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
+        public override bool CanConvertFrom(ITypeDescriptorContext? context, Type sourceType)
         {
             return sourceType == typeof(string);
         }
 
-        public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
+        public override object ConvertFrom(ITypeDescriptorContext? context, CultureInfo? culture, object value)
         {
             return Easing.Parse((string)value);
         }
diff --git a/src/Avalonia.Animation/IAnimation.cs b/src/Avalonia.Animation/IAnimation.cs
index d037834630..436a765d27 100644
--- a/src/Avalonia.Animation/IAnimation.cs
+++ b/src/Avalonia.Animation/IAnimation.cs
@@ -12,7 +12,7 @@ namespace Avalonia.Animation
         /// <summary>
         /// Apply the animation to the specified control and run it when <paramref name="match" /> produces <c>true</c>.
         /// </summary>
-        IDisposable Apply(Animatable control, IClock clock, IObservable<bool> match, Action onComplete = null);
+        IDisposable Apply(Animatable control, IClock? clock, IObservable<bool> match, Action? onComplete = null);
 
         /// <summary>
         /// Run the animation on the specified control.
diff --git a/src/Avalonia.Animation/IAnimationSetter.cs b/src/Avalonia.Animation/IAnimationSetter.cs
index 2d22377286..6a1d3539e2 100644
--- a/src/Avalonia.Animation/IAnimationSetter.cs
+++ b/src/Avalonia.Animation/IAnimationSetter.cs
@@ -2,7 +2,7 @@ namespace Avalonia.Animation
 {
     public interface IAnimationSetter
     {
-        AvaloniaProperty Property { get; set; }
-        object Value { get; set; }
+        AvaloniaProperty? Property { get; set; }
+        object? Value { get; set; }
     }
 }
diff --git a/src/Avalonia.Animation/IAnimator.cs b/src/Avalonia.Animation/IAnimator.cs
index d0fb173c54..f64ac9f913 100644
--- a/src/Avalonia.Animation/IAnimator.cs
+++ b/src/Avalonia.Animation/IAnimator.cs
@@ -11,11 +11,11 @@ namespace Avalonia.Animation
         /// <summary>
         /// The target property.
         /// </summary>
-        AvaloniaProperty Property {get; set;}
+        AvaloniaProperty? Property {get; set;}
 
         /// <summary>
         /// Applies the current KeyFrame group to the specified control.
         /// </summary>
-        IDisposable Apply(Animation animation, Animatable control, IClock clock, IObservable<bool> match, Action onComplete);
+        IDisposable? Apply(Animation animation, Animatable control, IClock? clock, IObservable<bool> match, Action? onComplete);
     }
 }
diff --git a/src/Avalonia.Animation/ITransition.cs b/src/Avalonia.Animation/ITransition.cs
index ade2ec8b9e..241ca208d1 100644
--- a/src/Avalonia.Animation/ITransition.cs
+++ b/src/Avalonia.Animation/ITransition.cs
@@ -10,7 +10,7 @@ namespace Avalonia.Animation
         /// <summary>
         /// Applies the transition to the specified <see cref="Animatable"/>.
         /// </summary>
-        IDisposable Apply(Animatable control, IClock clock, object oldValue, object newValue);
+        IDisposable Apply(Animatable control, IClock clock, object? oldValue, object? newValue);
 
         /// <summary>
         /// Gets the property to be animated.
diff --git a/src/Avalonia.Animation/IterationCount.cs b/src/Avalonia.Animation/IterationCount.cs
index 9463718608..3b52cdab49 100644
--- a/src/Avalonia.Animation/IterationCount.cs
+++ b/src/Avalonia.Animation/IterationCount.cs
@@ -97,7 +97,7 @@ namespace Avalonia.Animation
         /// </summary>
         /// <param name="o">The object with which to test equality.</param>
         /// <returns>True if the objects are equal, otherwise false.</returns>
-        public override bool Equals(object o)
+        public override bool Equals(object? o)
         {
             if (o == null)
             {
diff --git a/src/Avalonia.Animation/IterationCountTypeConverter.cs b/src/Avalonia.Animation/IterationCountTypeConverter.cs
index 1c63f8cdf1..f64972ff5c 100644
--- a/src/Avalonia.Animation/IterationCountTypeConverter.cs
+++ b/src/Avalonia.Animation/IterationCountTypeConverter.cs
@@ -6,12 +6,12 @@ namespace Avalonia.Animation
 {
     public class IterationCountTypeConverter : TypeConverter
     {
-        public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
+        public override bool CanConvertFrom(ITypeDescriptorContext? context, Type sourceType)
         {
             return sourceType == typeof(string);
         }
 
-        public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
+        public override object ConvertFrom(ITypeDescriptorContext? context, CultureInfo? culture, object value)
         {
             return IterationCount.Parse((string)value);
         }
diff --git a/src/Avalonia.Animation/KeyFrame.cs b/src/Avalonia.Animation/KeyFrame.cs
index c2cc1aa051..3ab7a70d90 100644
--- a/src/Avalonia.Animation/KeyFrame.cs
+++ b/src/Avalonia.Animation/KeyFrame.cs
@@ -19,7 +19,7 @@ namespace Avalonia.Animation
     {
         private TimeSpan _ktimeSpan;
         private Cue _kCue;
-        private KeySpline _kKeySpline;
+        private KeySpline? _kKeySpline;
 
         public KeyFrame()
         {
@@ -79,7 +79,7 @@ namespace Avalonia.Animation
         /// Gets or sets the KeySpline of this <see cref="KeyFrame"/>.
         /// </summary>
         /// <value>The key spline.</value>
-        public KeySpline KeySpline
+        public KeySpline? KeySpline
         {
             get
             {
diff --git a/src/Avalonia.Animation/KeySplineTypeConverter.cs b/src/Avalonia.Animation/KeySplineTypeConverter.cs
index b026206e5f..eecad3c3ac 100644
--- a/src/Avalonia.Animation/KeySplineTypeConverter.cs
+++ b/src/Avalonia.Animation/KeySplineTypeConverter.cs
@@ -12,12 +12,12 @@ namespace Avalonia.Animation
     /// </summary>
     public class KeySplineTypeConverter : TypeConverter
     {
-        public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
+        public override bool CanConvertFrom(ITypeDescriptorContext? context, Type sourceType)
         {
             return sourceType == typeof(string);
         }
 
-        public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
+        public override object ConvertFrom(ITypeDescriptorContext? context, CultureInfo? culture, object value)
         {
             return KeySpline.Parse((string)value, CultureInfo.InvariantCulture);
         }
diff --git a/src/Avalonia.Animation/Transition.cs b/src/Avalonia.Animation/Transition.cs
index 4115c95c0f..d307f348c4 100644
--- a/src/Avalonia.Animation/Transition.cs
+++ b/src/Avalonia.Animation/Transition.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using Avalonia.Animation.Easings;
 
 namespace Avalonia.Animation
@@ -8,7 +9,7 @@ namespace Avalonia.Animation
     /// </summary>
     public abstract class Transition<T> : AvaloniaObject, ITransition
     {
-        private AvaloniaProperty _prop;
+        private AvaloniaProperty? _prop;
 
         /// <summary>
         /// Gets or sets the duration of the transition.
@@ -26,7 +27,8 @@ namespace Avalonia.Animation
         public Easing Easing { get; set; } = new LinearEasing();
 
         /// <inheritdocs/>
-        public AvaloniaProperty Property
+        [DisallowNull]
+        public AvaloniaProperty? Property
         {
             get
             {
@@ -42,16 +44,25 @@ namespace Avalonia.Animation
             }
         }
 
+        AvaloniaProperty ITransition.Property
+        {
+            get => Property ?? throw new InvalidOperationException("Transition has no property specified.");
+            set => Property = value;
+        }
+
         /// <summary>
         /// Apply interpolation to the property.
         /// </summary>
         public abstract IObservable<T> DoTransition(IObservable<double> progress, T oldValue, T newValue);
 
         /// <inheritdocs/>
-        public virtual IDisposable Apply(Animatable control, IClock clock, object oldValue, object newValue)
+        public virtual IDisposable Apply(Animatable control, IClock clock, object? oldValue, object? newValue)
         {
-            var transition = DoTransition(new TransitionInstance(clock, Delay, Duration), (T)oldValue, (T)newValue);
+            if (Property is null)
+                throw new InvalidOperationException("Transition has no property specified.");
+
+            var transition = DoTransition(new TransitionInstance(clock, Delay, Duration), (T)oldValue!, (T)newValue!);
             return control.Bind<T>((AvaloniaProperty<T>)Property, transition, Data.BindingPriority.Animation);
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Avalonia.Animation/TransitionInstance.cs b/src/Avalonia.Animation/TransitionInstance.cs
index b522d1961e..9c9494ff87 100644
--- a/src/Avalonia.Animation/TransitionInstance.cs
+++ b/src/Avalonia.Animation/TransitionInstance.cs
@@ -10,11 +10,11 @@ namespace Avalonia.Animation
     /// </summary>
     internal class TransitionInstance : SingleSubscriberObservableBase<double>, IObserver<TimeSpan>
     {
-        private IDisposable _timerSubscription;
+        private IDisposable? _timerSubscription;
         private TimeSpan _delay;
         private TimeSpan _duration;
         private readonly IClock _baseClock;
-        private TransitionClock _clock;
+        private TransitionClock? _clock;
 
         public TransitionInstance(IClock clock, TimeSpan delay, TimeSpan duration)
         {
@@ -67,7 +67,7 @@ namespace Avalonia.Animation
         protected override void Unsubscribed()
         {
             _timerSubscription?.Dispose();
-            _clock.PlayState = PlayState.Stop;
+            _clock!.PlayState = PlayState.Stop;
         }
 
         protected override void Subscribed()
diff --git a/src/Avalonia.Base/Threading/AvaloniaSynchronizationContext.cs b/src/Avalonia.Base/Threading/AvaloniaSynchronizationContext.cs
index b991f9eb40..21649306cb 100644
--- a/src/Avalonia.Base/Threading/AvaloniaSynchronizationContext.cs
+++ b/src/Avalonia.Base/Threading/AvaloniaSynchronizationContext.cs
@@ -30,7 +30,7 @@ namespace Avalonia.Threading
         /// <inheritdoc/>
         public override void Post(SendOrPostCallback d, object? state)
         {
-           Dispatcher.UIThread.Post(() => d(state), DispatcherPriority.Send);
+           Dispatcher.UIThread.Post(() => d(state), DispatcherPriority.Background);
         }
 
         /// <inheritdoc/>
diff --git a/src/Avalonia.Controls.DataGrid/DataGrid.cs b/src/Avalonia.Controls.DataGrid/DataGrid.cs
index 10c7c16488..95ee73be4e 100644
--- a/src/Avalonia.Controls.DataGrid/DataGrid.cs
+++ b/src/Avalonia.Controls.DataGrid/DataGrid.cs
@@ -5751,6 +5751,7 @@ namespace Avalonia.Controls
                 return true;
             }
             // Unselect everything except the row that was clicked on
+            _noSelectionChangeCount++;
             try
             {
                 UpdateSelectionAndCurrency(columnIndex, slot, DataGridSelectionAction.SelectCurrent, scrollIntoView: false);
diff --git a/src/Avalonia.Controls.DataGrid/DataGridColumn.cs b/src/Avalonia.Controls.DataGrid/DataGridColumn.cs
index 6b515503aa..8501ce3896 100644
--- a/src/Avalonia.Controls.DataGrid/DataGridColumn.cs
+++ b/src/Avalonia.Controls.DataGrid/DataGridColumn.cs
@@ -448,7 +448,7 @@ namespace Avalonia.Controls
             internal set;
         }
 
-        public bool IsReadOnly
+        public virtual bool IsReadOnly
         {
             get
             {
diff --git a/src/Avalonia.Controls.DataGrid/DataGridTemplateColumn.cs b/src/Avalonia.Controls.DataGrid/DataGridTemplateColumn.cs
index 7e95dd100c..0e754d5815 100644
--- a/src/Avalonia.Controls.DataGrid/DataGridTemplateColumn.cs
+++ b/src/Avalonia.Controls.DataGrid/DataGridTemplateColumn.cs
@@ -1,4 +1,4 @@
-// (c) Copyright Microsoft Corporation.
+// (c) Copyright Microsoft Corporation.
 // This source is subject to the Microsoft Public License (Ms-PL).
 // Please see http://go.microsoft.com/fwlink/?LinkID=131993 for details.
 // All other rights reserved.
@@ -15,7 +15,7 @@ namespace Avalonia.Controls
 {
     public class DataGridTemplateColumn : DataGridColumn
     {
-        IDataTemplate _cellTemplate;
+        private IDataTemplate _cellTemplate;
 
         public static readonly DirectProperty<DataGridTemplateColumn, IDataTemplate> CellTemplateProperty =
             AvaloniaProperty.RegisterDirect<DataGridTemplateColumn, IDataTemplate>(
@@ -30,17 +30,38 @@ namespace Avalonia.Controls
             set { SetAndRaise(CellTemplateProperty, ref _cellTemplate, value); }
         }
 
+        private IDataTemplate _cellEditingCellTemplate;
+
+        /// <summary>
+        /// Defines the <see cref="CellEditingTemplate"/> property.
+        /// </summary>
+        public static readonly DirectProperty<DataGridTemplateColumn, IDataTemplate> CellEditingTemplateProperty =
+                AvaloniaProperty.RegisterDirect<DataGridTemplateColumn, IDataTemplate>(
+                    nameof(CellEditingTemplate),
+                    o => o.CellEditingTemplate,
+                    (o, v) => o.CellEditingTemplate = v);
+
+        /// <summary>
+        /// Gets or sets the <see cref="IDataTemplate"/> which is used for the editing mode of the current <see cref="DataGridCell"/>
+        /// </summary>
+        /// <value>
+        /// An <see cref="IDataTemplate"/> for the editing mode of the current <see cref="DataGridCell"/>
+        /// </value>
+        /// <remarks>
+        /// If this property is <see langword="null"/> the column is read-only.
+        /// </remarks>
+        public IDataTemplate CellEditingTemplate
+        {
+            get => _cellEditingCellTemplate;
+            set => SetAndRaise(CellEditingTemplateProperty, ref _cellEditingCellTemplate, value);
+        }
+        
         private void OnCellTemplateChanged(AvaloniaPropertyChangedEventArgs e)
         {
             var oldValue = (IDataTemplate)e.OldValue;
             var value = (IDataTemplate)e.NewValue;
         }
 
-        public DataGridTemplateColumn()
-        {
-            IsReadOnly = true;
-        }
-
         protected override IControl GenerateElement(DataGridCell cell, object dataItem)
         {
             if(CellTemplate != null)
@@ -60,7 +81,22 @@ namespace Avalonia.Controls
         protected override IControl GenerateEditingElement(DataGridCell cell, object dataItem, out ICellEditBinding binding)
         {
             binding = null;
-            return GenerateElement(cell, dataItem);
+            if(CellEditingTemplate != null)
+            {
+                return CellEditingTemplate.Build(dataItem);
+            }
+            else if (CellTemplate != null)
+            {
+                return CellTemplate.Build(dataItem);
+            }
+            if (Design.IsDesignMode)
+            {
+                return null;
+            }
+            else
+            {
+                throw DataGridError.DataGridTemplateColumn.MissingTemplateForType(typeof(DataGridTemplateColumn));
+            }
         }
 
         protected override object PrepareCellForEdit(IControl editingElement, RoutedEventArgs editingEventArgs)
@@ -70,12 +106,30 @@ namespace Avalonia.Controls
 
         protected internal override void RefreshCellContent(IControl element, string propertyName)
         {
-            if(propertyName == nameof(CellTemplate) && element.Parent is DataGridCell cell)
+            var cell = element.Parent as DataGridCell;
+            if(propertyName == nameof(CellTemplate) && cell is not null)
             {
                 cell.Content = GenerateElement(cell, cell.DataContext);
             }
 
             base.RefreshCellContent(element, propertyName);
         }
+        
+        public override bool IsReadOnly
+        {
+            get
+            {
+                if (CellEditingTemplate is null)
+                {
+                    return true;
+                }
+
+                return base.IsReadOnly;
+            }
+            set
+            {
+                base.IsReadOnly = value;
+            }
+        }
     }
 }
diff --git a/src/Avalonia.Dialogs/AboutAvaloniaDialog.xaml b/src/Avalonia.Dialogs/AboutAvaloniaDialog.xaml
index 08e8798cd5..c959fdc143 100644
--- a/src/Avalonia.Dialogs/AboutAvaloniaDialog.xaml
+++ b/src/Avalonia.Dialogs/AboutAvaloniaDialog.xaml
@@ -95,7 +95,7 @@
       </StackPanel>
       <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" >
         <TextBlock Text="Chat Room | " />
-        <Button Classes="Hyperlink" CommandParameter="https://gitter.im/AvaloniaUI/Avalonia/"  />
+        <Button Classes="Hyperlink" CommandParameter="https://t.me/Avalonia"  />
       </StackPanel>
      </StackPanel> 
     <StackPanel VerticalAlignment="Bottom" Margin="10">
diff --git a/src/Avalonia.Dialogs/Avalonia.Dialogs.csproj b/src/Avalonia.Dialogs/Avalonia.Dialogs.csproj
index 475a3655e4..770d15ea27 100644
--- a/src/Avalonia.Dialogs/Avalonia.Dialogs.csproj
+++ b/src/Avalonia.Dialogs/Avalonia.Dialogs.csproj
@@ -5,6 +5,7 @@
 
   <ItemGroup>
     <AvaloniaResource Include="Assets\*" />
+    <AvaloniaResource Include="**/*.xaml" />
   </ItemGroup>
 
   <Import Project="..\..\build\BuildTargets.targets" />
diff --git a/src/Avalonia.Input/KeyBinding.cs b/src/Avalonia.Input/KeyBinding.cs
index 856157eafa..7cb4f443f3 100644
--- a/src/Avalonia.Input/KeyBinding.cs
+++ b/src/Avalonia.Input/KeyBinding.cs
@@ -35,9 +35,11 @@ namespace Avalonia.Input
         {
             if (Gesture?.Matches(args) == true)
             {
-                args.Handled = true;
-                if (Command?.CanExecute(CommandParameter) == true)
+                if (Command?.CanExecute(CommandParameter) == true) 
+                {
+                    args.Handled = true;
                     Command.Execute(CommandParameter);
+                }
             }
         }
     }
diff --git a/src/Avalonia.Native/AvaloniaNativeMenuExporter.cs b/src/Avalonia.Native/AvaloniaNativeMenuExporter.cs
index 40ffc31728..de6ba30a85 100644
--- a/src/Avalonia.Native/AvaloniaNativeMenuExporter.cs
+++ b/src/Avalonia.Native/AvaloniaNativeMenuExporter.cs
@@ -70,74 +70,76 @@ namespace Avalonia.Native
             var result = new NativeMenu();
 
             var aboutItem = new NativeMenuItem("About Avalonia");
-            aboutItem.Click += async (sender, e) =>
+            
+            aboutItem.Click += async (_, _) =>
             {
                 var dialog = new AboutAvaloniaDialog();
 
-                var mainWindow = (Application.Current.ApplicationLifetime as IClassicDesktopStyleApplicationLifetime)?.MainWindow;
-
-                await dialog.ShowDialog(mainWindow);
+                if (Application.Current is
+                    { ApplicationLifetime: IClassicDesktopStyleApplicationLifetime { MainWindow: { } mainWindow } })
+                {
+                    await dialog.ShowDialog(mainWindow);   
+                }
             };
+            
             result.Add(aboutItem);
 
-            var macOpts = AvaloniaLocator.Current.GetService<MacOSPlatformOptions>() ?? new MacOSPlatformOptions();
-            if (!macOpts.DisableDefaultApplicationMenuItems)
-            {
-                result.Add(new NativeMenuItemSeparator());
+            return result;
+        }
 
-                var servicesMenu = new NativeMenuItem("Services");
-                servicesMenu.Menu = new NativeMenu
-                {
-                    [MacOSNativeMenuCommands.IsServicesSubmenuProperty] = true
-                };
-                result.Add(servicesMenu);
+        private void PopulateStandardOSXMenuItems(NativeMenu appMenu)
+        {
+            appMenu.Add(new NativeMenuItemSeparator());
 
-                result.Add(new NativeMenuItemSeparator());
+            var servicesMenu = new NativeMenuItem("Services");
+            servicesMenu.Menu = new NativeMenu { [MacOSNativeMenuCommands.IsServicesSubmenuProperty] = true };
 
-                var hideItem = new NativeMenuItem("Hide " + Application.Current.Name)
-                {
-                    Gesture = new KeyGesture(Key.H, KeyModifiers.Meta)
-                };
-                hideItem.Click += (sender, args) =>
-                {
-                    _applicationCommands.HideApp();
-                };
-                result.Add(hideItem);
+            appMenu.Add(servicesMenu);
 
+            appMenu.Add(new NativeMenuItemSeparator());
 
-                var hideOthersItem = new NativeMenuItem("Hide Others")
-                {
-                    Gesture = new KeyGesture(Key.Q, KeyModifiers.Meta | KeyModifiers.Alt)
-                };
-                hideOthersItem.Click += (sender, args) =>
-                {
-                    _applicationCommands.HideOthers();
-                };
-                result.Add(hideOthersItem);
+            var hideItem = new NativeMenuItem("Hide " + (Application.Current?.Name ?? "Application"))
+            {
+                Gesture = new KeyGesture(Key.H, KeyModifiers.Meta)
+            };
 
+            hideItem.Click += (_, _) =>
+            {
+                _applicationCommands.HideApp();
+            };
 
-                var showAllItem = new NativeMenuItem("Show All");
-                showAllItem.Click += (sender, args) =>
-                {
-                    _applicationCommands.ShowAll();
-                };
-                result.Add(showAllItem);
+            appMenu.Add(hideItem);
+
+            var hideOthersItem = new NativeMenuItem("Hide Others")
+            {
+                Gesture = new KeyGesture(Key.Q, KeyModifiers.Meta | KeyModifiers.Alt)
+            };
+            hideOthersItem.Click += (_, _) =>
+            {
+                _applicationCommands.HideOthers();
+            };
+            appMenu.Add(hideOthersItem);
 
-                result.Add(new NativeMenuItemSeparator());
+            var showAllItem = new NativeMenuItem("Show All");
+            showAllItem.Click += (_, _) =>
+            {
+                _applicationCommands.ShowAll();
+            };
 
-                var quitItem = new NativeMenuItem("Quit")
-                {
-                    Gesture = new KeyGesture(Key.Q, KeyModifiers.Meta)
-                };
-                quitItem.Click += (sender, args) =>
-                {
-                    (Application.Current.ApplicationLifetime as IControlledApplicationLifetime)?.Shutdown();
-                };
-                result.Add(quitItem);
-            }
+            appMenu.Add(showAllItem);
 
+            appMenu.Add(new NativeMenuItemSeparator());
 
-            return result;
+            var quitItem = new NativeMenuItem("Quit") { Gesture = new KeyGesture(Key.Q, KeyModifiers.Meta) };
+            quitItem.Click += (_, _) =>
+            {
+                if (Application.Current is { ApplicationLifetime: IControlledApplicationLifetime lifetime })
+                {
+                    lifetime.Shutdown();
+                }
+            };
+
+            appMenu.Add(quitItem);
         }
 
         private void DoLayoutReset(bool forceUpdate = false)
@@ -220,6 +222,13 @@ namespace Avalonia.Native
 
                 _nativeMenu.Initialize(this, appMenuHolder, "");
 
+                var macOpts = AvaloniaLocator.Current.GetService<MacOSPlatformOptions>();
+
+                if (macOpts == null || !macOpts.DisableDefaultApplicationMenuItems)
+                {
+                    PopulateStandardOSXMenuItems(menu);
+                }
+
                 setMenu = true;
             }
 
diff --git a/src/Avalonia.Themes.Fluent/Controls/CalendarButton.xaml b/src/Avalonia.Themes.Fluent/Controls/CalendarButton.xaml
index ca538e4b0a..3a6af60983 100644
--- a/src/Avalonia.Themes.Fluent/Controls/CalendarButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/CalendarButton.xaml
@@ -11,7 +11,7 @@
     <Setter Property="MinWidth" Value="40"/>
     <Setter Property="MinHeight" Value="40"/>
     <Setter Property="Margin" Value="1"/>
-    <Setter Property="Padding" Value="0,0,0,4"/>
+    <Setter Property="Padding" Value="0,0,0,0"/>
     <!--These are actually set on the CalendarView in WinUI-->
     <Setter Property="Foreground" Value="{DynamicResource CalendarViewCalendarItemForeground}"/>
     <Setter Property="Background" Value="{DynamicResource CalendarViewCalendarItemRevealBackground}"/>
diff --git a/src/Avalonia.Themes.Fluent/Controls/CalendarDayButton.xaml b/src/Avalonia.Themes.Fluent/Controls/CalendarDayButton.xaml
index ff72044c93..9223c0dd71 100644
--- a/src/Avalonia.Themes.Fluent/Controls/CalendarDayButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/CalendarDayButton.xaml
@@ -11,7 +11,7 @@
     <Setter Property="MinWidth" Value="40"/>
     <Setter Property="MinHeight" Value="40"/>
     <Setter Property="Margin" Value="1"/>
-    <Setter Property="Padding" Value="0,0,0,4"/>
+    <Setter Property="Padding" Value="0,0,0,0"/>
     <!--These are actually set on the CalendarView in WinUI-->
     <Setter Property="Foreground" Value="{DynamicResource CalendarViewCalendarItemForeground}"/>
     <Setter Property="Background" Value="{DynamicResource CalendarViewCalendarItemRevealBackground}"/>
diff --git a/src/Avalonia.Themes.Fluent/Controls/CalendarItem.xaml b/src/Avalonia.Themes.Fluent/Controls/CalendarItem.xaml
index 5bf3ac11af..2c1031f3e5 100644
--- a/src/Avalonia.Themes.Fluent/Controls/CalendarItem.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/CalendarItem.xaml
@@ -32,6 +32,7 @@
             <Style Selector="Button.CalendarHeader">
               <Setter Property="HorizontalAlignment" Value="Stretch" />
               <Setter Property="VerticalAlignment" Value="Stretch" />
+              <Setter Property="VerticalContentAlignment" Value="Center" />
               <Setter Property="FontSize" Value="20" />
               <Setter Property="Background" Value="{DynamicResource CalendarViewNavigationButtonBackground}"/>
               <Setter Property="Template">
diff --git a/src/Avalonia.Themes.Fluent/Controls/ListBox.xaml b/src/Avalonia.Themes.Fluent/Controls/ListBox.xaml
index 47704c12bd..1b4d66405b 100644
--- a/src/Avalonia.Themes.Fluent/Controls/ListBox.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/ListBox.xaml
@@ -20,6 +20,7 @@
     <Setter Property="Template">
       <ControlTemplate>
         <Border Name="border"
+                ClipToBounds="{TemplateBinding ClipToBounds}"
                 Background="{TemplateBinding Background}"
                 BorderBrush="{TemplateBinding BorderBrush}"
                 BorderThickness="{TemplateBinding BorderThickness}"
diff --git a/src/Avalonia.Visuals/Animation/Animators/BaseBrushAnimator.cs b/src/Avalonia.Visuals/Animation/Animators/BaseBrushAnimator.cs
index a2c4b0313b..5f22254fb5 100644
--- a/src/Avalonia.Visuals/Animation/Animators/BaseBrushAnimator.cs
+++ b/src/Avalonia.Visuals/Animation/Animators/BaseBrushAnimator.cs
@@ -38,8 +38,8 @@ namespace Avalonia.Animation.Animators
         }
 
         /// <inheritdoc/>
-        public override IDisposable Apply(Animation animation, Animatable control, IClock clock,
-            IObservable<bool> match, Action onComplete)
+        public override IDisposable? Apply(Animation animation, Animatable control, IClock? clock,
+            IObservable<bool> match, Action? onComplete)
         {
             if (TryCreateCustomRegisteredAnimator(out var animator)
                 || TryCreateGradientAnimator(out animator)
@@ -135,9 +135,8 @@ namespace Avalonia.Animation.Animators
 
         private bool TryCreateCustomRegisteredAnimator([NotNullWhen(true)] out IAnimator? animator)
         {
-            if (_brushAnimators.Count > 0)
+            if (_brushAnimators.Count > 0 && this[0].Value?.GetType() is Type firstKeyType)
             {
-                var firstKeyType = this[0].Value.GetType();
                 foreach (var (match, animatorType) in _brushAnimators)
                 {
                     if (!match(firstKeyType))
diff --git a/src/Avalonia.Visuals/Animation/Animators/GradientBrushAnimator.cs b/src/Avalonia.Visuals/Animation/Animators/GradientBrushAnimator.cs
index 864e12413f..0979de16d0 100644
--- a/src/Avalonia.Visuals/Animation/Animators/GradientBrushAnimator.cs
+++ b/src/Avalonia.Visuals/Animation/Animators/GradientBrushAnimator.cs
@@ -58,6 +58,11 @@ namespace Avalonia.Animation.Animators
 
         public override IDisposable BindAnimation(Animatable control, IObservable<IGradientBrush?> instance)
         {
+            if (Property is null)
+            {
+                throw new InvalidOperationException("Animator has no property specified.");
+            }
+
             return control.Bind((AvaloniaProperty<IBrush?>)Property, instance, BindingPriority.Animation);
         }
 
diff --git a/src/Avalonia.Visuals/Animation/Animators/SolidColorBrushAnimator.cs b/src/Avalonia.Visuals/Animation/Animators/SolidColorBrushAnimator.cs
index 7c6372aae2..57f9f3c1a5 100644
--- a/src/Avalonia.Visuals/Animation/Animators/SolidColorBrushAnimator.cs
+++ b/src/Avalonia.Visuals/Animation/Animators/SolidColorBrushAnimator.cs
@@ -24,6 +24,11 @@ namespace Avalonia.Animation.Animators
 
         public override IDisposable BindAnimation(Animatable control, IObservable<ISolidColorBrush?> instance)
         {
+            if (Property is null)
+            {
+                throw new InvalidOperationException("Animator has no property specified.");
+            }
+
             return control.Bind((AvaloniaProperty<IBrush?>)Property, instance, BindingPriority.Animation);
         }
     }
diff --git a/src/Avalonia.Visuals/Animation/Animators/TransformAnimator.cs b/src/Avalonia.Visuals/Animation/Animators/TransformAnimator.cs
index 1d7bfd3748..34ec8ac503 100644
--- a/src/Avalonia.Visuals/Animation/Animators/TransformAnimator.cs
+++ b/src/Avalonia.Visuals/Animation/Animators/TransformAnimator.cs
@@ -14,10 +14,15 @@ namespace Avalonia.Animation.Animators
         DoubleAnimator? _doubleAnimator;
 
         /// <inheritdoc/>
-        public override IDisposable? Apply(Animation animation, Animatable control, IClock clock, IObservable<bool> obsMatch, Action onComplete)
+        public override IDisposable? Apply(Animation animation, Animatable control, IClock? clock, IObservable<bool> obsMatch, Action? onComplete)
         {
             var ctrl = (Visual)control;
 
+            if (Property is null)
+            {
+                throw new InvalidOperationException("Animator has no property specified.");
+            }
+
             // Check if the Target Property is Transform derived.
             if (typeof(Transform).IsAssignableFrom(Property.OwnerType))
             {
diff --git a/src/Avalonia.Visuals/ApiCompatBaseline.txt b/src/Avalonia.Visuals/ApiCompatBaseline.txt
index dcb3246a63..68e3673cfe 100644
--- a/src/Avalonia.Visuals/ApiCompatBaseline.txt
+++ b/src/Avalonia.Visuals/ApiCompatBaseline.txt
@@ -7,6 +7,9 @@ InterfacesShouldHaveSameMembers : Interface member 'public System.Threading.Task
 MembersMustExist : Member 'public System.Threading.Tasks.Task Avalonia.Animation.PageSlide.Start(Avalonia.Visual, Avalonia.Visual, System.Boolean)' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'public void Avalonia.Media.GlyphRun..ctor()' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'public void Avalonia.Media.GlyphRun.GlyphTypeface.set(Avalonia.Media.GlyphTypeface)' does not exist in the implementation but it does exist in the contract.
+CannotSealType : Type 'Avalonia.Media.Pen' is actually (has the sealed modifier) sealed in the implementation but not sealed in the contract.
+MembersMustExist : Member 'protected void Avalonia.Media.Pen.AffectsRender<T>(Avalonia.AvaloniaProperty[])' does not exist in the implementation but it does exist in the contract.
+MembersMustExist : Member 'protected void Avalonia.Media.Pen.RaiseInvalidated(System.EventArgs)' does not exist in the implementation but it does exist in the contract.
 TypeCannotChangeClassification : Type 'Avalonia.Media.Immutable.ImmutableSolidColorBrush' is a 'class' in the implementation but is a 'struct' in the contract.
 MembersMustExist : Member 'public void Avalonia.Media.TextFormatting.DrawableTextRun.Draw(Avalonia.Media.DrawingContext)' does not exist in the implementation but it does exist in the contract.
 CannotAddAbstractMembers : Member 'public void Avalonia.Media.TextFormatting.DrawableTextRun.Draw(Avalonia.Media.DrawingContext, Avalonia.Point)' is abstract in the implementation but is missing in the contract.
@@ -83,4 +86,4 @@ InterfacesShouldHaveSameMembers : Interface member 'public Avalonia.Size Avaloni
 InterfacesShouldHaveSameMembers : Interface member 'public System.TimeSpan Avalonia.Platform.IPlatformSettings.TouchDoubleClickTime' is present in the implementation but not in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public Avalonia.Size Avalonia.Platform.IPlatformSettings.TouchDoubleClickSize.get()' is present in the implementation but not in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public System.TimeSpan Avalonia.Platform.IPlatformSettings.TouchDoubleClickTime.get()' is present in the implementation but not in the contract.
-Total Issues: 84
+Total Issues: 87
diff --git a/src/Avalonia.Visuals/Media/Pen.cs b/src/Avalonia.Visuals/Media/Pen.cs
index 7c966a35cf..65ba851100 100644
--- a/src/Avalonia.Visuals/Media/Pen.cs
+++ b/src/Avalonia.Visuals/Media/Pen.cs
@@ -7,7 +7,7 @@ namespace Avalonia.Media
     /// <summary>
     /// Describes how a stroke is drawn.
     /// </summary>
-    public class Pen : AvaloniaObject, IPen
+    public sealed class Pen : AvaloniaObject, IPen, IWeakEventSubscriber<EventArgs>
     {
         /// <summary>
         /// Defines the <see cref="Brush"/> property.
@@ -45,6 +45,10 @@ namespace Avalonia.Media
         public static readonly StyledProperty<double> MiterLimitProperty =
             AvaloniaProperty.Register<Pen, double>(nameof(MiterLimit), 10.0);
 
+        private EventHandler? _invalidated;
+        private IAffectsRender? _subscribedToBrush;
+        private IAffectsRender? _subscribedToDashes;
+        
         /// <summary>
         /// Initializes a new instance of the <see cref="Pen"/> class.
         /// </summary>
@@ -96,17 +100,6 @@ namespace Avalonia.Media
             DashStyle = dashStyle;
         }
 
-        static Pen()
-        {
-            AffectsRender<Pen>(
-                BrushProperty,
-                ThicknessProperty,
-                DashStyleProperty,
-                LineCapProperty,
-                LineJoinProperty,
-                MiterLimitProperty);
-        }
-
         /// <summary>
         /// Gets or sets the brush used to draw the stroke.
         /// </summary>
@@ -116,6 +109,11 @@ namespace Avalonia.Media
             set => SetValue(BrushProperty, value);
         }
 
+        private static readonly WeakEvent<IAffectsRender, EventArgs> InvalidatedWeakEvent =
+            WeakEvent.Register<IAffectsRender>(
+                (s, h) => s.Invalidated += h,
+                (s, h) => s.Invalidated -= h);
+
         /// <summary>
         /// Gets or sets the stroke thickness.
         /// </summary>
@@ -165,7 +163,19 @@ namespace Avalonia.Media
         /// <summary>
         /// Raised when the pen changes.
         /// </summary>
-        public event EventHandler? Invalidated;
+        public event EventHandler? Invalidated
+        {
+            add
+            {
+                _invalidated += value;
+                UpdateSubscriptions();
+            }
+            remove
+            {
+                _invalidated -= value; 
+                UpdateSubscriptions();
+            }
+        }
 
         /// <summary>
         /// Creates an immutable clone of the brush.
@@ -182,68 +192,42 @@ namespace Avalonia.Media
                 MiterLimit);
         }
 
-        /// <summary>
-        /// Marks a property as affecting the pen's visual representation.
-        /// </summary>
-        /// <param name="properties">The properties.</param>
-        /// <remarks>
-        /// After a call to this method in a pen's static constructor, any change to the
-        /// property will cause the <see cref="Invalidated"/> event to be raised on the pen.
-        /// </remarks>
-        protected static void AffectsRender<T>(params AvaloniaProperty[] properties)
-            where T : Pen
+        protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> change)
         {
-            static void Invalidate(AvaloniaPropertyChangedEventArgs e)
-            {
-                if (e.Sender is T sender)
-                {
-                    sender.RaiseInvalidated(EventArgs.Empty);
-                }
-            }
+            _invalidated?.Invoke(this, EventArgs.Empty);
+            if(change.Property == BrushProperty)
+                UpdateSubscription(ref _subscribedToBrush, Brush);
+            if(change.Property == DashStyleProperty)
+                UpdateSubscription(ref _subscribedToDashes, DashStyle);
+            base.OnPropertyChanged(change);
+        }
 
-            static void InvalidateAndSubscribe(AvaloniaPropertyChangedEventArgs e)
+        
+        void UpdateSubscription(ref IAffectsRender? field, object? value)
+        {
+            if ((_invalidated == null || field != value) && field != null)
             {
-                if (e.Sender is T sender)
-                {
-                    if (e.OldValue is IAffectsRender oldValue)
-                    {
-                        WeakEventHandlerManager.Unsubscribe<EventArgs, T>(
-                            oldValue,
-                            nameof(oldValue.Invalidated),
-                            sender.AffectsRenderInvalidated);
-                    }
-
-                    if (e.NewValue is IAffectsRender newValue)
-                    {
-                        WeakEventHandlerManager.Subscribe<IAffectsRender, EventArgs, T>(
-                            newValue,
-                            nameof(newValue.Invalidated),
-                            sender.AffectsRenderInvalidated);
-                    }
-
-                    sender.RaiseInvalidated(EventArgs.Empty);
-                }
+                InvalidatedWeakEvent.Unsubscribe(field, this);
+                field = null;
             }
 
-            foreach (var property in properties)
+            if (_invalidated != null && field != value && value is IAffectsRender affectsRender)
             {
-                if (property.CanValueAffectRender())
-                {
-                    property.Changed.Subscribe(e => InvalidateAndSubscribe(e));
-                }
-                else
-                {
-                    property.Changed.Subscribe(e => Invalidate(e));
-                }
+                InvalidatedWeakEvent.Subscribe(affectsRender, this);
+                field = affectsRender;
             }
         }
 
-        /// <summary>
-        /// Raises the <see cref="Invalidated"/> event.
-        /// </summary>
-        /// <param name="e">The event args.</param>
-        protected void RaiseInvalidated(EventArgs e) => Invalidated?.Invoke(this, e);
-
-        private void AffectsRenderInvalidated(object? sender, EventArgs e) => RaiseInvalidated(EventArgs.Empty);
+        void UpdateSubscriptions()
+        {
+            UpdateSubscription(ref _subscribedToBrush, Brush);
+            UpdateSubscription(ref _subscribedToDashes, DashStyle);
+        }
+        
+        void IWeakEventSubscriber<EventArgs>.OnEvent(object? sender, WeakEvent ev, EventArgs e)
+        {
+            if (ev == InvalidatedWeakEvent) 
+                _invalidated?.Invoke(this, EventArgs.Empty);
+        }
     }
 }
diff --git a/src/Skia/Avalonia.Skia/FormattedTextImpl.cs b/src/Skia/Avalonia.Skia/FormattedTextImpl.cs
index 81a79201d0..625d1c6f52 100644
--- a/src/Skia/Avalonia.Skia/FormattedTextImpl.cs
+++ b/src/Skia/Avalonia.Skia/FormattedTextImpl.cs
@@ -291,7 +291,7 @@ namespace Avalonia.Skia
                     {
                         AvaloniaFormattedTextLine line = _skiaLines[c];
 
-                        float x = TransformX(origin.X, 0, paint.TextAlign);
+                        float x = TransformX(origin.X, line.Width, paint.TextAlign);
 
                         if (!hasCusomFGBrushes)
                         {
diff --git a/tests/Avalonia.Animation.UnitTests/AnimatableTests.cs b/tests/Avalonia.Animation.UnitTests/AnimatableTests.cs
index 26d8059eec..1d5296bebd 100644
--- a/tests/Avalonia.Animation.UnitTests/AnimatableTests.cs
+++ b/tests/Avalonia.Animation.UnitTests/AnimatableTests.cs
@@ -36,7 +36,7 @@ namespace Avalonia.Animation.UnitTests
         [Fact]
         public void Transition_Is_Not_Applied_To_Initial_Style()
         {
-            using (UnitTestApplication.Start(TestServices.RealStyler))
+            using (Start())
             {
                 var target = CreateTarget();
                 var control = new Control
@@ -74,6 +74,7 @@ namespace Avalonia.Animation.UnitTests
         [Fact]
         public void Transition_Is_Applied_When_Local_Value_Changes()
         {
+            using var app = Start();
             var target = CreateTarget();
             var control = CreateControl(target.Object);
 
@@ -170,6 +171,7 @@ namespace Avalonia.Animation.UnitTests
         [Fact]
         public void Transition_Is_Not_Applied_When_StyleTrigger_Changes_With_LocalValue_Present()
         {
+            using var app = Start();
             var target = CreateTarget();
             var control = CreateControl(target.Object);
 
@@ -195,6 +197,7 @@ namespace Avalonia.Animation.UnitTests
         [Fact]
         public void Transition_Is_Disposed_When_Local_Value_Changes()
         {
+            using var app = Start();
             var target = CreateTarget();
             var control = CreateControl(target.Object);
             var sub = new Mock<IDisposable>();
@@ -211,6 +214,7 @@ namespace Avalonia.Animation.UnitTests
         [Fact]
         public void New_Transition_Is_Applied_When_Local_Value_Changes()
         {
+            using var app = Start();
             var target = CreateTarget();
             var control = CreateControl(target.Object);
 
@@ -239,6 +243,7 @@ namespace Avalonia.Animation.UnitTests
         [Fact]
         public void Transition_Is_Not_Applied_When_Removed_From_Visual_Tree()
         {
+            using var app = Start();
             var target = CreateTarget();
             var control = CreateControl(target.Object);
 
@@ -266,6 +271,7 @@ namespace Avalonia.Animation.UnitTests
         [Fact]
         public void Animation_Is_Cancelled_When_Transition_Removed()
         {
+            using var app = Start();
             var target = CreateTarget();
             var control = CreateControl(target.Object);
             var sub = new Mock<IDisposable>();
@@ -285,7 +291,7 @@ namespace Avalonia.Animation.UnitTests
         [Fact]
         public void Animation_Is_Cancelled_When_New_Style_Activates()
         {
-            using (UnitTestApplication.Start(TestServices.RealStyler))
+            using (Start())
             {
                 var target = CreateTarget();
                 var control = CreateStyledControl(target.Object);
@@ -301,7 +307,7 @@ namespace Avalonia.Animation.UnitTests
 
                 target.Verify(x => x.Apply(
                     control,
-                    It.IsAny<Clock>(),
+                    It.IsAny<IClock>(),
                     1.0,
                     0.5),
                     Times.Once);
@@ -315,7 +321,7 @@ namespace Avalonia.Animation.UnitTests
         [Fact]
         public void Transition_From_Style_Trigger_Is_Applied()
         {
-            using (UnitTestApplication.Start(TestServices.RealStyler))
+            using (Start())
             {
                 var target = CreateTransition(Control.WidthProperty);
                 var control = CreateStyledControl(transition2: target.Object);
@@ -326,7 +332,7 @@ namespace Avalonia.Animation.UnitTests
 
                 target.Verify(x => x.Apply(
                     control,
-                    It.IsAny<Clock>(),
+                    It.IsAny<IClock>(),
                     double.NaN,
                     100.0),
                     Times.Once);
@@ -337,7 +343,7 @@ namespace Avalonia.Animation.UnitTests
         public void Replacing_Transitions_During_Animation_Does_Not_Throw_KeyNotFound()
         {
             // Issue #4059
-            using (UnitTestApplication.Start(TestServices.RealStyler))
+            using (Start())
             {
                 Border target;
                 var clock = new TestClock();
@@ -428,6 +434,13 @@ namespace Avalonia.Animation.UnitTests
             control.EndBatchUpdate();
         }
 
+        private static IDisposable Start()
+        {
+            var clock = new MockGlobalClock();
+            var services = TestServices.RealStyler.With(globalClock: clock);
+            return UnitTestApplication.Start(services);
+        }
+
         private static Mock<ITransition> CreateTarget()
         {
             return CreateTransition(Visual.OpacityProperty);