Merge branch 'master' into demo/dynamic-menus

samples/RenderDemo/Pages/AnimationsPage.xaml

@@ -107,9 +107,12 @@
   </UserControl.Styles>
   <Grid>
     <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center" ClipToBounds="False">
+      <StackPanel.Clock>
+          <Clock />
+      </StackPanel.Clock>
       <StackPanel Orientation="Horizontal" VerticalAlignment="Center">
         <TextBlock VerticalAlignment="Center">Hover to activate Transform Keyframe Animations.</TextBlock>
-        <Button Content="{Binding PlayStateText}" Command="{Binding ToggleGlobalPlayState}"/>
+        <Button Content="{Binding PlayStateText}" Command="{Binding TogglePlayState}" Click="ToggleClock" />
       </StackPanel>
       <WrapPanel ClipToBounds="False">
         <Border Classes="Test Rect1" Background="DarkRed"/>
@@ -120,4 +123,4 @@
       </WrapPanel>
     </StackPanel>
   </Grid>
-</UserControl>
+</UserControl>

samples/RenderDemo/Pages/AnimationsPage.xaml.cs

@@ -5,6 +5,7 @@ using Avalonia.Controls;
 using Avalonia.Controls.Shapes;
 using Avalonia.Data;
 using Avalonia.Input;
+using Avalonia.Interactivity;
 using Avalonia.Markup.Xaml;
 using Avalonia.Media;
 using RenderDemo.ViewModels;
@@ -23,5 +24,20 @@ namespace RenderDemo.Pages
         {
             AvaloniaXamlLoader.Load(this);
         }
+
+        private void ToggleClock(object sender, RoutedEventArgs args)
+        {
+            var button = sender as Button;
+            var clock = button.Clock;
+
+            if (clock.PlayState == PlayState.Run)
+            {
+                clock.PlayState = PlayState.Pause;
+            }
+            else if (clock.PlayState == PlayState.Pause)
+            {
+                clock.PlayState = PlayState.Run;
+            }
+        }
     }
 }

samples/RenderDemo/ViewModels/AnimationsPageViewModel.cs

@@ -6,27 +6,15 @@ namespace RenderDemo.ViewModels
 {
     public class AnimationsPageViewModel : ReactiveObject
     {
-        private string _playStateText = "Pause all animations";
+        private bool _isPlaying = true;
 
-        public AnimationsPageViewModel()
+        private string _playStateText = "Pause animations on this page";
-        {
-            ToggleGlobalPlayState = ReactiveCommand.Create(() => TogglePlayState());
-        }
 
-        void TogglePlayState()
+        public void TogglePlayState()
         {
-            switch (Animation.GlobalPlayState)
+            PlayStateText = _isPlaying
-            {
+                ? "Resume animations on this page" : "Pause animations on this page";
-                case PlayState.Run:
+            _isPlaying = !_isPlaying;
-                    PlayStateText = "Resume all animations";
-                    Animation.GlobalPlayState = PlayState.Pause;
-                    break;
-
-                case PlayState.Pause:
-                    PlayStateText = "Pause all animations";
-                    Animation.GlobalPlayState = PlayState.Run;
-                    break;
-            }
         }
 
         public string PlayStateText
@@ -34,7 +22,5 @@ namespace RenderDemo.ViewModels
             get { return _playStateText; }
             set { this.RaiseAndSetIfChanged(ref _playStateText, value); }
         }
-
-        public ReactiveCommand ToggleGlobalPlayState { get; }
     }
 }

src/Android/Avalonia.Android/AndroidPlatform.cs

@@ -52,7 +52,8 @@ namespace Avalonia.Android
                 .Bind<ISystemDialogImpl>().ToTransient<SystemDialogImpl>()
                 .Bind<IWindowingPlatform>().ToConstant(Instance)
                 .Bind<IPlatformIconLoader>().ToSingleton<PlatformIconLoader>()
-                .Bind<IRenderLoop>().ToConstant(new DefaultRenderLoop(60))
+                .Bind<IRenderTimer>().ToConstant(new DefaultRenderTimer(60))
+                .Bind<IRenderLoop>().ToConstant(new RenderLoop())
                 .Bind<IAssetLoader>().ToConstant(new AssetLoader(app.GetType().Assembly));
 
             SkiaPlatform.Initialize();

src/Avalonia.Animation/Animatable.cs

@@ -14,26 +14,14 @@ namespace Avalonia.Animation
     /// Base class for all animatable objects.
     /// </summary>
     public class Animatable : AvaloniaObject
-    { 
+    {
-        /// <summary>
+        public static readonly StyledProperty<IClock> ClockProperty =
-        /// Defines the <see cref="PlayState"/> property.
+            AvaloniaProperty.Register<Animatable, IClock>(nameof(Clock), inherits: true);
-        /// </summary>
-        public static readonly DirectProperty<Animatable, PlayState> PlayStateProperty =
-            AvaloniaProperty.RegisterDirect<Animatable, PlayState>(
-                nameof(PlayState),
-                o => o.PlayState,
-                (o, v) => o.PlayState = v);
-
-        private PlayState _playState = PlayState.Run;
 
-        /// <summary>
+        public IClock Clock
-        /// Gets or sets the state of the animation for this
-        /// control.
-        /// </summary>
-        public PlayState PlayState
         {
-            get { return _playState; }
+            get => GetValue(ClockProperty);
-            set { SetAndRaise(PlayStateProperty, ref _playState, value); }
+            set => SetValue(ClockProperty, value);
         }
 
         /// <summary>
@@ -69,9 +57,9 @@ namespace Avalonia.Animation
 
                 if (match != null)
                 {
-                    match.Apply(this, e.OldValue, e.NewValue);
+                    match.Apply(this, Clock ?? Avalonia.Animation.Clock.GlobalClock, e.OldValue, e.NewValue);
                 }
             }
         }
     }
-}
+}

src/Avalonia.Animation/Animation.cs

@@ -17,11 +17,6 @@ namespace Avalonia.Animation
     /// </summary>
     public class Animation : AvaloniaList<KeyFrame>, IAnimation
     {
-        /// <summary>
-        /// Gets or sets the animation play state for all animations
-        /// </summary> 
-        public static PlayState GlobalPlayState { get; set; } = PlayState.Run;
-
         /// <summary>
         /// Gets or sets the active time of this animation.
         /// </summary>
@@ -149,12 +144,12 @@ namespace Avalonia.Animation
         }
 
         /// <inheritdocs/>
-        public IDisposable Apply(Animatable control, 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, match, onComplete));
+                subscriptions.Add(animators[0].Apply(this, control, clock, match, onComplete));
             }
             else
             {
@@ -168,7 +163,7 @@ namespace Avalonia.Animation
                         animatorOnComplete = () => tcs.SetResult(null);
                         completionTasks.Add(tcs.Task);
                     }
-                    subscriptions.Add(animator.Apply(this, control, match, animatorOnComplete));
+                    subscriptions.Add(animator.Apply(this, control, clock, match, animatorOnComplete));
                 }
 
                 if (onComplete != null)
@@ -180,7 +175,7 @@ namespace Avalonia.Animation
         }
 
         /// <inheritdocs/>
-        public Task RunAsync(Animatable control)
+        public Task RunAsync(Animatable control, IClock clock = null)
         {
             var run = new TaskCompletionSource<object>();
 
@@ -188,7 +183,7 @@ namespace Avalonia.Animation
                 run.SetException(new InvalidOperationException("Looping animations must not use the Run method."));
 
             IDisposable subscriptions = null;
-            subscriptions = this.Apply(control, Observable.Return(true), () =>
+            subscriptions = this.Apply(control, clock, Observable.Return(true), () =>
             {
                 run.SetResult(null);
                 subscriptions?.Dispose();

src/Avalonia.Animation/AnimationInstance`1.cs

@@ -8,7 +8,7 @@ using Avalonia.Reactive;
 namespace Avalonia.Animation
 {
     /// <summary>
-    /// Handles interpolatoin and time-related functions 
+    /// Handles interpolation and time-related functions 
     /// for keyframe animations.
     /// </summary>
     internal class AnimationInstance<T> : SingleSubscriberObservableBase<T>
@@ -19,7 +19,6 @@ namespace Avalonia.Animation
         private double _currentIteration;
         private bool _isLooping;
         private bool _gotFirstKFValue;
-        private bool _gotFirstFrameCount;
         private bool _iterationDelay;
         private FillMode _fillMode;
         private PlaybackDirection _animationDirection;
@@ -29,15 +28,14 @@ namespace Avalonia.Animation
         private double _speedRatio;
         private TimeSpan _delay;
         private TimeSpan _duration;
-        private TimeSpan _firstFrameCount;
-        private TimeSpan _internalClock;
-        private TimeSpan? _previousClock;
         private Easings.Easing _easeFunc;
         private Action _onCompleteAction;
         private Func<double, T, T> _interpolator;
         private IDisposable _timerSubscription;
+        private readonly IClock _baseClock;
+        private IClock _clock;
 
-        public AnimationInstance(Animation animation, Animatable control, Animator<T> animator, 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)
         {
             if (animation.SpeedRatio <= 0)
                 throw new InvalidOperationException("Speed ratio cannot be negative or zero.");
@@ -73,17 +71,19 @@ namespace Avalonia.Animation
             _fillMode = animation.FillMode;
             _onCompleteAction = OnComplete;
             _interpolator = Interpolator;
+            _baseClock = baseClock;
         }
 
         protected override void Unsubscribed()
         {
             _timerSubscription?.Dispose();
+            _clock.PlayState = PlayState.Stop;
         }
 
         protected override void Subscribed()
         {
-            _timerSubscription = Timing.AnimationsTimer
+            _clock = new Clock(_baseClock);
-                                       .Subscribe(p => this.Step(p));
+            _timerSubscription = _clock.Subscribe(Step);
         }
 
         public void Step(TimeSpan frameTick)
@@ -116,46 +116,21 @@ namespace Avalonia.Animation
                     PublishNext(_lastInterpValue);
         }
 
-        private void DoPlayStatesAndTime(TimeSpan systemTime)
+        private void DoPlayStates()
         {
-            if (Animation.GlobalPlayState == PlayState.Stop || _targetControl.PlayState == PlayState.Stop)
+            if (_clock.PlayState == PlayState.Stop || _baseClock.PlayState == PlayState.Stop)
                 DoComplete();
 
-            if (!_previousClock.HasValue)
-            {
-                _previousClock = systemTime;
-                _internalClock = TimeSpan.Zero;
-            }
-            else
-            {
-                if (Animation.GlobalPlayState == PlayState.Pause || _targetControl.PlayState == PlayState.Pause)
-                {
-                    _previousClock = systemTime;
-                    return;
-                }
-                var delta = systemTime - _previousClock;
-                _internalClock += delta.Value;
-                _previousClock = systemTime;
-            }
-
             if (!_gotFirstKFValue)
             {
                 _firstKFValue = (T)_parent.First().Value;
                 _gotFirstKFValue = true;
             }
-
-            if (!_gotFirstFrameCount)
-            {
-                _firstFrameCount = _internalClock;
-                _gotFirstFrameCount = true;
-            }
         }
 
-        private void InternalStep(TimeSpan systemTime)
+        private void InternalStep(TimeSpan time)
         {
-            DoPlayStatesAndTime(systemTime);
+            DoPlayStates();
- 
-            var time = _internalClock - _firstFrameCount;
             var delayEndpoint = _delay;
             var iterationEndpoint = delayEndpoint + _duration;
 
@@ -176,22 +151,18 @@ namespace Avalonia.Animation
                 }
 
                 //Calculate the current iteration number
-                _currentIteration = (int)Math.Floor((double)time.Ticks / iterationEndpoint.Ticks) + 2;
+                _currentIteration = (int)Math.Floor((double)((double)time.Ticks / iterationEndpoint.Ticks)) + 2;
             }
             else
             {
-                _previousClock = systemTime;
                 return;
             }
 
-            time = TimeSpan.FromTicks(time.Ticks % iterationEndpoint.Ticks);
+            time = TimeSpan.FromTicks((long)(time.Ticks % iterationEndpoint.Ticks));
 
             if (!_isLooping)
             {
-                if (_currentIteration > _repeatCount)
+                if ((_currentIteration > _repeatCount) || (time > iterationEndpoint))
-                    DoComplete();
-
-                if (time > iterationEndpoint)
                     DoComplete();
             }
 
@@ -225,4 +196,4 @@ namespace Avalonia.Animation
             }
         }
     }
-}
+}

src/Avalonia.Animation/Animator`1.cs

@@ -1,10 +1,14 @@
-using System;
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Reactive.Linq;
 using Avalonia.Animation.Utils;
 using Avalonia.Collections;
 using Avalonia.Data;
+using Avalonia.Reactive;
 
 namespace Avalonia.Animation
 {
@@ -17,7 +21,7 @@ namespace Avalonia.Animation
         /// List of type-converted keyframes.
         /// </summary>
         private readonly List<AnimatorKeyFrame> _convertedKeyframes = new List<AnimatorKeyFrame>();
- 
+
         private bool _isVerifiedAndConverted;
 
         /// <summary>
@@ -28,21 +32,17 @@ namespace Avalonia.Animation
         public Animator()
         {
             // Invalidate keyframes when changed.
-             this.CollectionChanged += delegate { _isVerifiedAndConverted = false; };
+            this.CollectionChanged += delegate { _isVerifiedAndConverted = false; };
         }
 
         /// <inheritdoc/>
-        public virtual IDisposable Apply(Animation animation, Animatable control, IObservable<bool> match, Action onComplete)
+        public virtual IDisposable Apply(Animation animation, Animatable control, IClock clock, IObservable<bool> match, Action onComplete)
         {
-             if (!_isVerifiedAndConverted)
+            if (!_isVerifiedAndConverted)
                 VerifyConvertKeyFrames();
 
-            return match
+            var subject = new DisposeAnimationInstanceSubject<T>(this, animation, control, clock, onComplete);
-                .Where(p => p)
+            return match.Subscribe(subject);
-                .Subscribe(_ =>
-                {
-                    var timerObs = RunKeyFrames(animation, control, onComplete);
-                });
         }
 
         /// <summary>
@@ -52,58 +52,84 @@ namespace Avalonia.Animation
         /// (i.e., the normalized time between the selected keyframes, relative to the
         /// time parameter).
         /// </summary>
-        /// <param name="t">The time parameter, relative to the total animation time</param>
+        /// <param name="animationTime">The time parameter, relative to the total animation time</param>
-        protected (double IntraKFTime, KeyFramePair<T> KFPair) GetKFPairAndIntraKFTime(double t)
+        protected (double IntraKFTime, KeyFramePair<T> KFPair) GetKFPairAndIntraKFTime(double animationTime)
         {
-            AnimatorKeyFrame firstCue, lastCue ;
+            AnimatorKeyFrame firstKeyframe, lastKeyframe;
             int kvCount = _convertedKeyframes.Count;
             if (kvCount > 2)
             {
-                if (t <= 0.0)
+                if (animationTime <= 0.0)
                 {
-                    firstCue = _convertedKeyframes[0];
+                    firstKeyframe = _convertedKeyframes[0];
-                    lastCue = _convertedKeyframes[1];
+                    lastKeyframe = _convertedKeyframes[1];
                 }
-                else if (t >= 1.0)
+                else if (animationTime >= 1.0)
                 {
-                    firstCue = _convertedKeyframes[_convertedKeyframes.Count - 2];
+                    firstKeyframe = _convertedKeyframes[_convertedKeyframes.Count - 2];
-                    lastCue = _convertedKeyframes[_convertedKeyframes.Count - 1];
+                    lastKeyframe = _convertedKeyframes[_convertedKeyframes.Count - 1];
                 }
                 else
                 {
-                    (double time, int index) maxval = (0.0d, 0);
+                    int index = FindClosestBeforeKeyFrame(animationTime);
-                    for (int i = 0; i < _convertedKeyframes.Count; i++)
+                    firstKeyframe = _convertedKeyframes[index];
-                    {
+                    lastKeyframe = _convertedKeyframes[index + 1];
-                        var comp = _convertedKeyframes[i].Cue.CueValue;
-                        if (t >= comp)
-                        {
-                            maxval = (comp, i);
-                        }
-                    }
-                    firstCue = _convertedKeyframes[maxval.index];
-                    lastCue = _convertedKeyframes[maxval.index + 1];
                 }
             }
             else
             {
-                firstCue = _convertedKeyframes[0];
+                firstKeyframe = _convertedKeyframes[0];
-                lastCue = _convertedKeyframes[1];
+                lastKeyframe = _convertedKeyframes[1];
             }
 
-            double t0 = firstCue.Cue.CueValue;
+            double t0 = firstKeyframe.Cue.CueValue;
-            double t1 = lastCue.Cue.CueValue;
+            double t1 = lastKeyframe.Cue.CueValue;
-            var intraframeTime = (t - t0) / (t1 - t0);
+            var intraframeTime = (animationTime - t0) / (t1 - t0);
-            var firstFrameData = (firstCue.GetTypedValue<T>(), firstCue.isNeutral);
+            var firstFrameData = (firstKeyframe.GetTypedValue<T>(), firstKeyframe.isNeutral);
-            var lastFrameData = (lastCue.GetTypedValue<T>(), lastCue.isNeutral);
+            var lastFrameData = (lastKeyframe.GetTypedValue<T>(), lastKeyframe.isNeutral);
             return (intraframeTime, new KeyFramePair<T>(firstFrameData, lastFrameData));
         }
 
+        private int FindClosestBeforeKeyFrame(double time)
+        {
+            int FindClosestBeforeKeyFrame(int startIndex, int length)
+            {
+                if (length == 0 || length == 1)
+                {
+                    return startIndex;
+                }
+
+                int middle = startIndex + (length / 2);
+
+                if (_convertedKeyframes[middle].Cue.CueValue < time)
+                {
+                    return FindClosestBeforeKeyFrame(middle, length - middle);
+                }
+                else if (_convertedKeyframes[middle].Cue.CueValue > time)
+                {
+                    return FindClosestBeforeKeyFrame(startIndex, middle - startIndex);
+                }
+                else
+                {
+                    return middle;
+                }
+            }
+
+            return FindClosestBeforeKeyFrame(0, _convertedKeyframes.Count);
+        }
+
         /// <summary>
         /// Runs the KeyFrames Animation.
         /// </summary>
-        private IDisposable RunKeyFrames(Animation animation, Animatable control, Action onComplete)
+        internal IDisposable Run(Animation animation, Animatable control, IClock clock, Action onComplete)
         {
-            var instance = new AnimationInstance<T>(animation, control, this, onComplete, DoInterpolation);
+            var instance = new AnimationInstance<T>(
+                animation,
+                control,
+                this,
+                clock ?? control.Clock ?? Clock.GlobalClock,
+                onComplete,
+                DoInterpolation);
             return control.Bind<T>((AvaloniaProperty<T>)Property, instance, BindingPriority.Animation);
         }
 
@@ -124,14 +150,6 @@ namespace Avalonia.Animation
 
             AddNeutralKeyFramesIfNeeded();
 
-            var copy = _convertedKeyframes.ToList().OrderBy(p => p.Cue.CueValue);
-            _convertedKeyframes.Clear();
-
-            foreach (AnimatorKeyFrame keyframe in copy)
-            {
-                _convertedKeyframes.Add(keyframe);
-            }
-
             _isVerifiedAndConverted = true;
         }
 
@@ -161,7 +179,7 @@ namespace Avalonia.Animation
         {
             if (!hasStartKey)
             {
-                _convertedKeyframes.Add(new AnimatorKeyFrame(null, new Cue(0.0d)) { Value = default(T), isNeutral = true });
+                _convertedKeyframes.Insert(0, new AnimatorKeyFrame(null, new Cue(0.0d)) { Value = default(T), isNeutral = true });
             }
 
             if (!hasEndKey)
@@ -170,4 +188,4 @@ namespace Avalonia.Animation
             }
         }
     }
-}
+}

src/Avalonia.Animation/Clock.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Collections.Generic;
+using System.Reactive.Linq;
+using System.Text;
+using Avalonia.Reactive;
+
+namespace Avalonia.Animation
+{
+    public class Clock : ClockBase
+    {
+        public static IClock GlobalClock => AvaloniaLocator.Current.GetService<IGlobalClock>();
+
+        private IDisposable _parentSubscription;
+
+        public Clock()
+            :this(GlobalClock)
+        {
+        }
+        
+        public Clock(IClock parent)
+        {
+            _parentSubscription = parent.Subscribe(Pulse);
+        }
+
+        protected override void Stop()
+        {
+            _parentSubscription?.Dispose();
+        }
+    }
+}

src/Avalonia.Animation/ClockBase.cs

@@ -0,0 +1,72 @@
+using System;
+using System.Collections.Generic;
+using System.Reactive.Linq;
+using System.Text;
+using Avalonia.Reactive;
+
+namespace Avalonia.Animation
+{
+    public class ClockBase : IClock
+    {
+        private ClockObservable _observable;
+
+        private IObservable<TimeSpan> _connectedObservable;
+
+        private TimeSpan? _previousTime;
+        private TimeSpan _internalTime;
+
+        protected ClockBase()
+        {
+            _observable = new ClockObservable();
+            _connectedObservable = _observable.Publish().RefCount();
+        }
+
+        protected bool HasSubscriptions => _observable.HasSubscriptions;
+
+        public PlayState PlayState { get; set; }
+
+        protected void Pulse(TimeSpan systemTime)
+        {
+            if (!_previousTime.HasValue)
+            {
+                _previousTime = systemTime;
+                _internalTime = TimeSpan.Zero;
+            }
+            else
+            {
+                if (PlayState == PlayState.Pause)
+                {
+                    _previousTime = systemTime;
+                    return;
+                }
+                var delta = systemTime - _previousTime;
+                _internalTime += delta.Value;
+                _previousTime = systemTime;
+            }
+
+            _observable.Pulse(_internalTime);
+
+            if (PlayState == PlayState.Stop)
+            {
+                Stop();
+            }
+        }
+
+        protected virtual void Stop()
+        {
+        }
+
+        public IDisposable Subscribe(IObserver<TimeSpan> observer)
+        {
+            return _connectedObservable.Subscribe(observer);
+        }
+
+        private class ClockObservable : LightweightObservableBase<TimeSpan>
+        {
+            public bool HasSubscriptions { get; private set; }
+            public void Pulse(TimeSpan time) => PublishNext(time);
+            protected override void Initialize() => HasSubscriptions = true;
+            protected override void Deinitialize() => HasSubscriptions = false;
+        }
+    }
+}

src/Avalonia.Animation/DisposeAnimationInstanceSubject.cs

@@ -0,0 +1,65 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reactive.Linq;
+using Avalonia.Animation.Utils;
+using Avalonia.Collections;
+using Avalonia.Data;
+using Avalonia.Reactive;
+
+namespace Avalonia.Animation
+{
+    /// <summary>
+    /// Manages the lifetime of animation instances as determined by its selector state.
+    /// </summary>
+    internal class DisposeAnimationInstanceSubject<T> : IObserver<bool>, IDisposable
+    {
+        private IDisposable _lastInstance;
+        private bool _lastMatch;
+        private Animator<T> _animator;
+        private Animation _animation;
+        private Animatable _control;
+        private Action _onComplete;
+        private IClock _clock;
+
+        public DisposeAnimationInstanceSubject(Animator<T> animator, Animation animation, Animatable control, IClock clock, Action onComplete)
+        {
+            this._animator = animator;
+            this._animation = animation;
+            this._control = control;
+            this._onComplete = onComplete;
+            this._clock = clock;
+        }
+
+
+        public void Dispose()
+        {
+            _lastInstance?.Dispose();
+        }
+
+        public void OnCompleted()
+        {
+        }
+
+        public void OnError(Exception error)
+        {
+            _lastInstance?.Dispose();
+        }
+
+        void IObserver<bool>.OnNext(bool matchVal)
+        {
+            if (matchVal != _lastMatch)
+            {
+                _lastInstance?.Dispose();
+                if (matchVal)
+                {
+                    _lastInstance = _animator.Run(_animation, _control, _clock, _onComplete);
+                }
+                _lastMatch = matchVal;
+            }
+        }
+    }
+}

src/Avalonia.Animation/DoubleAnimator.cs

@@ -1,4 +1,7 @@
-namespace Avalonia.Animation
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+namespace Avalonia.Animation
 {
     /// <summary>
     /// Animator that handles <see cref="double"/> properties.

src/Avalonia.Animation/FillMode.cs

@@ -1,4 +1,7 @@
-namespace Avalonia.Animation
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+namespace Avalonia.Animation
 {
     public enum FillMode
     {

src/Avalonia.Animation/IAnimation.cs

@@ -1,3 +1,6 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
 using System;
 using System.Threading.Tasks;
 
@@ -9,13 +12,13 @@ namespace Avalonia.Animation
     public interface IAnimation
     {
         /// <summary>
-        /// Apply the animation to the specified control
+        /// Apply the animation to the specified control and run it when <paramref name="match" /> produces <c>true</c>.
         /// </summary>
-        IDisposable Apply(Animatable control, IObservable<bool> match, Action onComplete = null);
+        IDisposable Apply(Animatable control, IClock clock, IObservable<bool> match, Action onComplete = null);
 
         /// <summary>
-        /// Run the animation to the specified control
+        /// Run the animation on the specified control.
         /// </summary>
-        Task RunAsync(Animatable control);
+        Task RunAsync(Animatable control, IClock clock);
     }
 }

src/Avalonia.Animation/IAnimationSetter.cs

@@ -1,3 +1,6 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
 namespace Avalonia.Animation
 {
     public interface IAnimationSetter

src/Avalonia.Animation/IAnimator.cs

@@ -1,4 +1,7 @@
-using System;
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
 using System.Collections.Generic;
 
 namespace Avalonia.Animation
@@ -16,6 +19,6 @@ namespace Avalonia.Animation
         /// <summary>
         /// Applies the current KeyFrame group to the specified control.
         /// </summary>
-        IDisposable Apply(Animation animation, Animatable control, IObservable<bool> obsMatch, Action onComplete);
+        IDisposable Apply(Animation animation, Animatable control, IClock clock, IObservable<bool> match, Action onComplete);
     }
 }

src/Avalonia.Animation/IClock.cs

@@ -0,0 +1,11 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Avalonia.Animation
+{
+    public interface IClock : IObservable<TimeSpan>
+    {
+        PlayState PlayState { get; set; }
+    }
+}

src/Avalonia.Animation/IGlobalClock.cs

@@ -0,0 +1,10 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Avalonia.Animation
+{
+    public interface IGlobalClock : IClock
+    {
+    }
+}

src/Avalonia.Animation/ITransition.cs

@@ -13,7 +13,7 @@ namespace Avalonia.Animation
         /// <summary>
         /// Applies the transition to the specified <see cref="Animatable"/>.
         /// </summary>
-        IDisposable Apply(Animatable control, object oldValue, object newValue);
+        IDisposable Apply(Animatable control, IClock clock, object oldValue, object newValue);
 
         /// <summary>
         /// Gets the property to be animated.

src/Avalonia.Animation/KeyFrame.cs

@@ -1,4 +1,7 @@
-using System;
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
 using System.Collections.Generic;
 using Avalonia.Collections;
 

src/Avalonia.Animation/KeyFramePair`1.cs

@@ -1,3 +1,6 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
 namespace Avalonia.Animation
 {
     /// <summary>

src/Avalonia.Animation/PlayState.cs

@@ -1,4 +1,7 @@
-namespace Avalonia.Animation
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+namespace Avalonia.Animation
 {
     /// <summary>
     /// Determines the playback state of an animation.

src/Avalonia.Animation/PlaybackDirection.cs

@@ -1,4 +1,7 @@
-namespace Avalonia.Animation
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+namespace Avalonia.Animation
 {
     /// <summary>
     /// Determines the playback direction of an animation.

src/Avalonia.Animation/Timing.cs

@@ -1,54 +0,0 @@
-// Copyright (c) The Avalonia Project. All rights reserved.
-// Licensed under the MIT license. See licence.md file in the project root for full license information.
-
-using System;
-using System.Linq;
-using System.Reactive.Linq;
-using Avalonia.Threading;
-
-namespace Avalonia.Animation
-{
-    /// <summary>
-    /// Provides global timing functions for animations.
-    /// </summary>
-    public static class Timing
-    {
-        /// <summary>
-        /// The number of frames per second.
-        /// </summary>
-        public const int FramesPerSecond = 60;
-
-        /// <summary>
-        /// The time span of each frame.
-        /// </summary>
-        internal static readonly TimeSpan FrameTick = TimeSpan.FromSeconds(1.0 / FramesPerSecond);
-
-        /// <summary>
-        /// Initializes static members of the <see cref="Timing"/> class.
-        /// </summary>
-        static Timing()
-        { 
-            var globalTimer = Observable.Interval(FrameTick, AvaloniaScheduler.Instance);
-
-            AnimationsTimer = globalTimer
-                .Select(_ => GetTickCount())
-                .Publish()
-                .RefCount();
-        }
-
-        internal static TimeSpan GetTickCount() => TimeSpan.FromMilliseconds(Environment.TickCount);
-
-        /// <summary>
-        /// Gets the animation timer.
-        /// </summary>
-        /// <remarks>
-        /// The animation timer triggers usually at 60 times per second or as
-        /// defined in <see cref="FramesPerSecond"/>.
-        /// The parameter passed to a subsciber is the current playstate of the animation.
-        /// </remarks>
-        internal static IObservable<TimeSpan> AnimationsTimer
-        {
-            get;
-        }
-    }
-}

src/Avalonia.Animation/TransitionInstance.cs

@@ -15,21 +15,22 @@ namespace Avalonia.Animation
     /// </summary>
     internal class TransitionInstance : SingleSubscriberObservableBase<double>
     {
-        private IDisposable timerSubscription;
+        private IDisposable _timerSubscription;
-        private TimeSpan startTime;
+        private TimeSpan _duration;
-        private TimeSpan duration;
+        private readonly IClock _baseClock;
+        private IClock _clock;
 
-        public TransitionInstance(TimeSpan Duration)
+        public TransitionInstance(IClock clock, TimeSpan Duration)
         {
-            duration = Duration;
+            _duration = Duration;
+            _baseClock = clock;
         }
 
         private void TimerTick(TimeSpan t)
         {
-            var interpVal = (double)(t.Ticks - startTime.Ticks) / duration.Ticks;
+            var interpVal = (double)t.Ticks / _duration.Ticks;
 
-            if (interpVal > 1d
+            if (interpVal > 1d || interpVal < 0d)
-             || interpVal < 0d)
             {
                 PublishCompleted();
                 return;
@@ -40,15 +41,15 @@ namespace Avalonia.Animation
 
         protected override void Unsubscribed()
         {
-            timerSubscription?.Dispose();
+            _timerSubscription?.Dispose();
+            _clock.PlayState = PlayState.Stop;
         }
 
         protected override void Subscribed()
         {
-            startTime = Timing.GetTickCount();
+            _clock = new Clock(_baseClock);
-            timerSubscription = Timing.AnimationsTimer
+            _timerSubscription = _clock.Subscribe(TimerTick);
-                                      .Subscribe(t => TimerTick(t));
             PublishNext(0.0d);
         }
     }
-}
+}

src/Avalonia.Animation/Transition`1.cs

@@ -14,7 +14,6 @@ namespace Avalonia.Animation
     public abstract class Transition<T> : AvaloniaObject, ITransition
     {
         private AvaloniaProperty _prop;
-        private Easing _easing;
 
         /// <summary>
         /// Gets the duration of the animation.
@@ -49,12 +48,10 @@ namespace Avalonia.Animation
         public abstract IObservable<T> DoTransition(IObservable<double> progress, T oldValue, T newValue);
 
         /// <inheritdocs/>
-        public virtual IDisposable Apply(Animatable control, object oldValue, object newValue)
+        public virtual IDisposable Apply(Animatable control, IClock clock, object oldValue, object newValue)
         {
-            var transition = DoTransition(new TransitionInstance(Duration), (T)oldValue, (T)newValue);
+            var transition = DoTransition(new TransitionInstance(clock, Duration), (T)oldValue, (T)newValue);
             return control.Bind<T>((AvaloniaProperty<T>)Property, transition, Data.BindingPriority.Animation);
         }
-
-
     }
 }

src/Avalonia.Base/PriorityBindingEntry.cs

@@ -50,6 +50,11 @@ namespace Avalonia
             get;
         }
 
+        /// <summary>
+        /// Gets a value indicating whether the binding has completed.
+        /// </summary>
+        public bool HasCompleted { get; private set; }
+
         /// <summary>
         /// The current value of the binding.
         /// </summary>
@@ -129,6 +134,8 @@ namespace Avalonia
 
         private void Completed()
         {
+            HasCompleted = true;
+
             if (Dispatcher.UIThread.CheckAccess())
             {
                 _owner.Completed(this);

src/Avalonia.Base/PriorityLevel.cs

@@ -112,12 +112,16 @@ namespace Avalonia
 
             return Disposable.Create(() =>
             {
-                Bindings.Remove(node);
+                if (!entry.HasCompleted)
-                entry.Dispose();
-
-                if (entry.Index >= ActiveBindingIndex)
                 {
-                    ActivateFirstBinding();
+                    Bindings.Remove(node);
+
+                    entry.Dispose();
+
+                    if (entry.Index >= ActiveBindingIndex)
+                    {
+                        ActivateFirstBinding();
+                    }
                 }
             });
         }

src/Avalonia.Base/Reactive/LightweightObservableBase.cs

@@ -82,18 +82,10 @@ namespace Avalonia.Reactive
                         if (observers.Count == 0)
                         {
                             observers.TrimExcess();
+                            Deinitialize();
                         }
-                        else
-                        {
-                            return;
-                        }
-                    } else
-                    {
-                        return;
                     }
                 }
-
-                Deinitialize();
             }
         }
 

src/Avalonia.Base/Reactive/ObservableEx.cs

@@ -21,7 +21,7 @@ namespace Avalonia.Reactive
         {
             return new SingleValueImpl<T>(value);
         }
-
+ 
         private class SingleValueImpl<T> : IObservable<T>
         {
             private T _value;
@@ -30,7 +30,6 @@ namespace Avalonia.Reactive
             {
                 _value = value;
             }
-
             public IDisposable Subscribe(IObserver<T> observer)
             {
                 observer.OnNext(_value);
@@ -38,4 +37,4 @@ namespace Avalonia.Reactive
             }
         }
     }
-}
+}

src/Avalonia.Controls/AppBuilderBase.cs

@@ -272,10 +272,10 @@ namespace Avalonia.Controls
 
             s_setupWasAlreadyCalled = true;
 
-            Instance.RegisterServices();
             RuntimePlatformServicesInitializer();
             WindowingSubsystemInitializer();
             RenderingSubsystemInitializer();
+            Instance.RegisterServices();
             Instance.Initialize();
             AfterSetupCallback(Self);
         }

src/Avalonia.Controls/Application.cs

@@ -4,12 +4,14 @@
 using System;
 using System.Reactive.Concurrency;
 using System.Threading;
+using Avalonia.Animation;
 using Avalonia.Controls;
 using Avalonia.Controls.Templates;
 using Avalonia.Input;
 using Avalonia.Input.Platform;
 using Avalonia.Input.Raw;
 using Avalonia.Platform;
+using Avalonia.Rendering;
 using Avalonia.Styling;
 using Avalonia.Threading;
 
@@ -335,6 +337,11 @@ namespace Avalonia
                 .Bind<IScheduler>().ToConstant(AvaloniaScheduler.Instance)
                 .Bind<IDragDropDevice>().ToConstant(DragDropDevice.Instance)
                 .Bind<IPlatformDragSource>().ToTransient<InProcessDragSource>();
+
+            var clock = new RenderLoopClock();
+            AvaloniaLocator.CurrentMutable
+                .Bind<IGlobalClock>().ToConstant(clock)
+                .GetService<IRenderLoop>()?.Add(clock);
         }
     }
 }

src/Avalonia.Controls/Border.cs

@@ -43,7 +43,11 @@ namespace Avalonia.Controls
         /// </summary>
         static Border()
         {
-            AffectsRender<Border>(BackgroundProperty, BorderBrushProperty, BorderThicknessProperty, CornerRadiusProperty);
+            AffectsRender<Border>(
+                BackgroundProperty,
+                BorderBrushProperty,
+                BorderThicknessProperty,
+                CornerRadiusProperty);
             AffectsMeasure<Border>(BorderThicknessProperty);
         }
 

src/Avalonia.Controls/MenuItem.cs

@@ -99,13 +99,13 @@ namespace Avalonia.Controls
             SelectableMixin.Attach<MenuItem>(IsSelectedProperty);
             CommandProperty.Changed.Subscribe(CommandChanged);
             FocusableProperty.OverrideDefaultValue<MenuItem>(true);
+            HeaderProperty.Changed.AddClassHandler<MenuItem>(x => x.HeaderChanged);
             IconProperty.Changed.AddClassHandler<MenuItem>(x => x.IconChanged);
             IsSelectedProperty.Changed.AddClassHandler<MenuItem>(x => x.IsSelectedChanged);
             ItemsPanelProperty.OverrideDefaultValue<MenuItem>(DefaultPanel);
             ClickEvent.AddClassHandler<MenuItem>(x => x.OnClick);
             SubmenuOpenedEvent.AddClassHandler<MenuItem>(x => x.OnSubmenuOpened);
             IsSubMenuOpenProperty.Changed.AddClassHandler<MenuItem>(x => x.SubMenuOpenChanged);
-            PseudoClass<MenuItem, object>(HeaderProperty, x => x as string == "-", ":separator");
         }
 
         public MenuItem()
@@ -420,6 +420,24 @@ namespace Avalonia.Controls
             IsEnabled = Command == null || Command.CanExecute(CommandParameter);
         }
 
+        /// <summary>
+        /// Called when the <see cref="Header"/> property changes.
+        /// </summary>
+        /// <param name="e">The property change event.</param>
+        private void HeaderChanged(AvaloniaPropertyChangedEventArgs e)
+        {
+            if (e.NewValue is string newValue && newValue == "-")
+            {
+                PseudoClasses.Add(":separator");
+                Focusable = false;
+            }
+            else if (e.OldValue is string oldValue && oldValue == "-")
+            {
+                PseudoClasses.Remove(":separator");
+                Focusable = true;
+            }
+        }
+
         /// <summary>
         /// Called when the <see cref="Icon"/> property changes.
         /// </summary>

src/Avalonia.Controls/Panel.cs

@@ -30,6 +30,7 @@ namespace Avalonia.Controls
         /// </summary>
         static Panel()
         {
+            AffectsRender<Panel>(BackgroundProperty);
             ClipToBoundsProperty.OverrideDefaultValue<Panel>(true);
         }
 

src/Avalonia.Controls/Platform/InternalPlatformThreadingInterface.cs

@@ -9,12 +9,15 @@ using Avalonia.Threading;
 
 namespace Avalonia.Controls.Platform
 {
-    public class InternalPlatformThreadingInterface : IPlatformThreadingInterface, IRenderLoop
+    public class InternalPlatformThreadingInterface : IPlatformThreadingInterface, IRenderTimer
     {
         public InternalPlatformThreadingInterface()
         {
             TlsCurrentThreadIsLoopThread = true;
-            StartTimer(DispatcherPriority.Render, new TimeSpan(0, 0, 0, 0, 66), () => Tick?.Invoke(this, new EventArgs()));
+            StartTimer(
+                DispatcherPriority.Render,
+                new TimeSpan(0, 0, 0, 0, 66),
+                () => Tick?.Invoke(TimeSpan.FromMilliseconds(Environment.TickCount)));
         }
 
         private readonly AutoResetEvent _signaled = new AutoResetEvent(false);
@@ -105,7 +108,7 @@ namespace Avalonia.Controls.Platform
 
         public bool CurrentThreadIsLoopThread => TlsCurrentThreadIsLoopThread;
         public event Action<DispatcherPriority?> Signaled;
-        public event EventHandler<EventArgs> Tick;
+        public event Action<TimeSpan> Tick;
 
     }
-}
+}

src/Avalonia.Controls/Primitives/AdornerLayer.cs

@@ -6,11 +6,12 @@ using System.Collections.Specialized;
 using System.Linq;
 using Avalonia.VisualTree;
 using Avalonia.Media;
+using Avalonia.Rendering;
 
 namespace Avalonia.Controls.Primitives
 {
     // TODO: Need to track position of adorned elements and move the adorner if they move.
-    public class AdornerLayer : Panel
+    public class AdornerLayer : Panel, ICustomSimpleHitTest
     {
         public static AttachedProperty<Visual> AdornedElementProperty =
             AvaloniaProperty.RegisterAttached<AdornerLayer, Visual, Visual>("AdornedElement");
@@ -137,6 +138,11 @@ namespace Avalonia.Controls.Primitives
             }
         }
 
+        public bool HitTest(Point point)
+        {
+            return Children.Any(ctrl => ctrl.TransformedBounds?.Contains(point) == true);
+        }
+
         private class AdornedElementInfo
         {
             public IDisposable Subscription { get; set; }

src/Avalonia.Controls/ProgressBar.cs

@@ -37,7 +37,8 @@ namespace Avalonia.Controls
             PseudoClass<ProgressBar, Orientation>(OrientationProperty, o => o == Avalonia.Controls.Orientation.Horizontal, ":horizontal");
             PseudoClass<ProgressBar>(IsIndeterminateProperty, ":indeterminate");
 
-            ValueProperty.Changed.AddClassHandler<ProgressBar>(x => x.ValueChanged);
+            ValueProperty.Changed.AddClassHandler<ProgressBar>(x => x.UpdateIndicatorWhenPropChanged);
+            IsIndeterminateProperty.Changed.AddClassHandler<ProgressBar>(x => x.UpdateIndicatorWhenPropChanged);
         }
 
         public bool IsIndeterminate
@@ -114,9 +115,9 @@ namespace Avalonia.Controls
             }
         }
 
-        private void ValueChanged(AvaloniaPropertyChangedEventArgs e)
+        private void UpdateIndicatorWhenPropChanged(AvaloniaPropertyChangedEventArgs e)
         {
             UpdateIndicator(Bounds.Size);
         }
     }
-}
+}

src/Avalonia.Controls/TextBlock.cs

@@ -6,6 +6,7 @@ using System.Reactive;
 using System.Reactive.Linq;
 using Avalonia.LogicalTree;
 using Avalonia.Media;
+using Avalonia.Media.Immutable;
 using Avalonia.Metadata;
 
 namespace Avalonia.Controls
@@ -65,7 +66,7 @@ namespace Avalonia.Controls
         public static readonly AttachedProperty<IBrush> ForegroundProperty =
             AvaloniaProperty.RegisterAttached<TextBlock, Control, IBrush>(
                 nameof(Foreground),
-                new SolidColorBrush(0xff000000),
+                Brushes.Black,
                 inherits: true);
 
         /// <summary>
@@ -100,6 +101,7 @@ namespace Avalonia.Controls
         {
             ClipToBoundsProperty.OverrideDefaultValue<TextBlock>(true);
             AffectsRender<TextBlock>(
+                BackgroundProperty,
                 ForegroundProperty,
                 FontWeightProperty,
                 FontSizeProperty,

src/Avalonia.Controls/TopLevel.cs

@@ -96,7 +96,6 @@ namespace Avalonia.Controls
             _applicationLifecycle = TryGetService<IApplicationLifecycle>(dependencyResolver);
             _renderInterface = TryGetService<IPlatformRenderInterface>(dependencyResolver);
 
-            var renderLoop = TryGetService<IRenderLoop>(dependencyResolver);
             Renderer = impl.CreateRenderer(this);
 
             impl.SetInputRoot(this);

src/Avalonia.DesignerSupport/Remote/PreviewerWindowingPlatform.cs

@@ -53,7 +53,8 @@ namespace Avalonia.DesignerSupport.Remote
                 .Bind<IKeyboardDevice>().ToConstant(Keyboard)
                 .Bind<IPlatformSettings>().ToConstant(instance)
                 .Bind<IPlatformThreadingInterface>().ToConstant(threading)
-                .Bind<IRenderLoop>().ToConstant(threading)
+                .Bind<IRenderLoop>().ToConstant(new RenderLoop())
+                .Bind<IRenderTimer>().ToConstant(threading)
                 .Bind<ISystemDialogImpl>().ToSingleton<SystemDialogsStub>()
                 .Bind<IWindowingPlatform>().ToConstant(instance)
                 .Bind<IPlatformIconLoader>().ToSingleton<IconLoaderStub>();

src/Avalonia.Diagnostics/Avalonia.Diagnostics.csproj

@@ -2,6 +2,9 @@
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
   </PropertyGroup>
+  <ItemGroup>
+    <None Remove="Views\EventsView.xaml" />
+  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\Markup\Avalonia.Markup.Xaml\Avalonia.Markup.Xaml.csproj" />
     <ProjectReference Include="..\Markup\Avalonia.Markup\Avalonia.Markup.csproj" />
@@ -17,4 +20,9 @@
   </ItemGroup>  
   <Import Project="..\..\build\EmbedXaml.props" />
   <Import Project="..\..\build\Rx.props" />
+  <ItemGroup>
+    <EmbeddedResource Update="Views\EventsView.xaml">
+      <Generator>MSBuild:Compile</Generator>
+    </EmbeddedResource>
+  </ItemGroup>
 </Project>

src/Avalonia.Diagnostics/DevTools.xaml

@@ -3,6 +3,7 @@
     <TabStrip SelectedIndex="{Binding SelectedTab, Mode=TwoWay}">
       <TabStripItem Content="Logical Tree"/>
       <TabStripItem Content="Visual Tree"/>
+      <TabStripItem Content="Events"/>
     </TabStrip>
 
     <ContentControl Content="{Binding Content}" Grid.Row="1"/> 

src/Avalonia.Diagnostics/DevTools.xaml.cs

@@ -10,6 +10,7 @@ using Avalonia.Input;
 using Avalonia.Input.Raw;
 using Avalonia.Interactivity;
 using Avalonia.Markup.Xaml;
+using Avalonia.Rendering;
 using Avalonia.VisualTree;
 
 namespace Avalonia
@@ -28,6 +29,7 @@ namespace Avalonia.Diagnostics
 	public class DevTools : UserControl
     {
         private static Dictionary<TopLevel, Window> s_open = new Dictionary<TopLevel, Window>();
+        private static HashSet<IRenderRoot> s_visualTreeRoots = new HashSet<IRenderRoot>();
         private IDisposable _keySubscription;
 
         public DevTools(IControl root)
@@ -79,6 +81,7 @@ namespace Avalonia.Diagnostics
 
                     devToolsWindow.Closed += devTools.DevToolsClosed;
                     s_open.Add(control, devToolsWindow);
+                    MarkAsDevTool(devToolsWindow);
                     devToolsWindow.Show();
                 }
             }
@@ -89,6 +92,7 @@ namespace Avalonia.Diagnostics
             var devToolsWindow = (Window)sender;
             var devTools = (DevTools)devToolsWindow.Content;
             s_open.Remove((TopLevel)devTools.Root);
+            RemoveDevTool(devToolsWindow);
             _keySubscription.Dispose();
             devToolsWindow.Closed -= DevToolsClosed;
         }
@@ -116,5 +120,24 @@ namespace Avalonia.Diagnostics
                 }
             }
         }
+
+        /// <summary>
+        /// Marks a visual as part of the DevTools, so it can be excluded from event tracking.
+        /// </summary>
+        /// <param name="visual">The visual whose root is to be marked.</param>
+        public static void MarkAsDevTool(IVisual visual)
+        {
+            s_visualTreeRoots.Add(visual.GetVisualRoot());
+        }
+
+        public static void RemoveDevTool(IVisual visual)
+        {
+            s_visualTreeRoots.Remove(visual.GetVisualRoot());
+        }
+
+        public static bool BelongsToDevTool(IVisual visual)
+        {
+            return s_visualTreeRoots.Contains(visual.GetVisualRoot());
+        }
     }
 }

src/Avalonia.Diagnostics/Models/EventChainLink.cs

@@ -0,0 +1,38 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
+using Avalonia.Interactivity;
+
+namespace Avalonia.Diagnostics.Models
+{
+    internal class EventChainLink
+    {
+        public EventChainLink(object handler, bool handled, RoutingStrategies route)
+        {
+            Contract.Requires<ArgumentNullException>(handler != null);
+
+            this.Handler = handler;
+            this.Handled = handled;
+            this.Route = route;
+        }
+
+        public object Handler { get; }
+
+        public string HandlerName
+        {
+            get
+            {
+                if (Handler is INamed named && !string.IsNullOrEmpty(named.Name))
+                {
+                    return named.Name + " (" + Handler.GetType().Name + ")";
+                }
+                return Handler.GetType().Name;
+            }
+        }
+
+        public bool Handled { get; }
+
+        public RoutingStrategies Route { get; }
+    }
+}

src/Avalonia.Diagnostics/ViewModels/DevToolsViewModel.cs

@@ -14,6 +14,7 @@ namespace Avalonia.Diagnostics.ViewModels
         private int _selectedTab;
         private TreePageViewModel _logicalTree;
         private TreePageViewModel _visualTree;
+        private EventsViewModel _eventsView;
         private string _focusedControl;
         private string _pointerOverElement;
 
@@ -21,6 +22,7 @@ namespace Avalonia.Diagnostics.ViewModels
         {
             _logicalTree = new TreePageViewModel(LogicalTreeNode.Create(root));
             _visualTree = new TreePageViewModel(VisualTreeNode.Create(root));
+            _eventsView = new EventsViewModel(root);
 
             UpdateFocusedControl();
             KeyboardDevice.Instance.PropertyChanged += (s, e) =>
@@ -57,6 +59,9 @@ namespace Avalonia.Diagnostics.ViewModels
                     case 1:
                         Content = _visualTree;
                         break;
+                    case 2:
+                        Content = _eventsView;
+                        break;
                 }
 
                 RaisePropertyChanged();

src/Avalonia.Diagnostics/ViewModels/EventOwnerTreeNode.cs

@@ -0,0 +1,61 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Avalonia.Collections;
+using Avalonia.Controls;
+using Avalonia.Input;
+using Avalonia.Interactivity;
+
+namespace Avalonia.Diagnostics.ViewModels
+{
+    internal class EventOwnerTreeNode : EventTreeNodeBase
+    {
+        private static readonly RoutedEvent[] s_defaultEvents = new RoutedEvent[]
+        {
+           Button.ClickEvent,
+           InputElement.KeyDownEvent,
+           InputElement.KeyUpEvent,
+           InputElement.TextInputEvent,
+           InputElement.PointerReleasedEvent,
+           InputElement.PointerPressedEvent,
+        };
+
+        public EventOwnerTreeNode(Type type, IEnumerable<RoutedEvent> events, EventsViewModel vm)
+            : base(null, type.Name)
+        {
+            this.Children = new AvaloniaList<EventTreeNodeBase>(events.OrderBy(e => e.Name)
+                .Select(e => new EventTreeNode(this, e, vm) { IsEnabled = s_defaultEvents.Contains(e) }));
+            this.IsExpanded = true;
+        }
+
+        public override bool? IsEnabled
+        {
+            get => base.IsEnabled;
+            set
+            {
+                if (base.IsEnabled != value)
+                {
+                    base.IsEnabled = value;
+                    if (_updateChildren && value != null)
+                    {
+                        foreach (var child in Children)
+                        {
+                            try
+                            {
+                                child._updateParent = false;
+                                child.IsEnabled = value;
+                            }
+                            finally
+                            {
+                                child._updateParent = true;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}

src/Avalonia.Diagnostics/ViewModels/EventTreeNode.cs

@@ -0,0 +1,98 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
+
+using Avalonia.Diagnostics.Models;
+using Avalonia.Interactivity;
+using Avalonia.Threading;
+using Avalonia.VisualTree;
+
+namespace Avalonia.Diagnostics.ViewModels
+{
+    internal class EventTreeNode : EventTreeNodeBase
+    {
+        private RoutedEvent _event;
+        private EventsViewModel _parentViewModel;
+        private bool _isRegistered;
+        private FiredEvent _currentEvent;
+
+        public EventTreeNode(EventOwnerTreeNode parent, RoutedEvent @event, EventsViewModel vm)
+            : base(parent, @event.Name)
+        {
+            Contract.Requires<ArgumentNullException>(@event != null);
+            Contract.Requires<ArgumentNullException>(vm != null);
+
+            this._event = @event;
+            this._parentViewModel = vm;
+        }
+
+        public override bool? IsEnabled
+        {
+            get => base.IsEnabled;
+            set
+            {
+                if (base.IsEnabled != value)
+                {
+                    base.IsEnabled = value;
+                    UpdateTracker();
+                    if (Parent != null && _updateParent)
+                    {
+                        try
+                        {
+                            Parent._updateChildren = false;
+                            Parent.UpdateChecked();
+                        }
+                        finally
+                        {
+                            Parent._updateChildren = true;
+                        }
+                    }
+                }
+            }
+        }
+
+        private void UpdateTracker()
+        {
+            if (IsEnabled.GetValueOrDefault() && !_isRegistered)
+            {
+                _event.AddClassHandler(typeof(object), HandleEvent, (RoutingStrategies)7, handledEventsToo: true);
+                _isRegistered = true;
+            }
+        }
+
+        private void HandleEvent(object sender, RoutedEventArgs e)
+        {
+            if (!_isRegistered || IsEnabled == false)
+                return;
+            if (sender is IVisual v && DevTools.BelongsToDevTool(v))
+                return;
+
+            var s = sender;
+            var handled = e.Handled;
+            var route = e.Route;
+
+            Action handler = delegate
+            {
+                if (_currentEvent == null || !_currentEvent.IsPartOfSameEventChain(e))
+                {
+                    _currentEvent = new FiredEvent(e, new EventChainLink(s, handled, route));
+
+                    _parentViewModel.RecordedEvents.Add(_currentEvent);
+
+                    while (_parentViewModel.RecordedEvents.Count > 100)
+                        _parentViewModel.RecordedEvents.RemoveAt(0);
+                }
+                else
+                {
+                    _currentEvent.AddToChain(new EventChainLink(s, handled, route));
+                }
+            };
+
+            if (!Dispatcher.UIThread.CheckAccess())
+                Dispatcher.UIThread.Post(handler);
+            else
+                handler();
+        }
+    }
+}

src/Avalonia.Diagnostics/ViewModels/EventTreeNodeBase.cs

@@ -0,0 +1,78 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using Avalonia.Collections;
+
+namespace Avalonia.Diagnostics.ViewModels
+{
+    internal abstract class EventTreeNodeBase : ViewModelBase
+    {
+        internal bool _updateChildren = true;
+        internal bool _updateParent = true;
+        private bool _isExpanded;
+        private bool? _isEnabled = false;
+
+        public EventTreeNodeBase(EventTreeNodeBase parent, string text)
+        {
+            this.Parent = parent;
+            this.Text = text;
+        }
+
+        public IAvaloniaReadOnlyList<EventTreeNodeBase> Children
+        {
+            get;
+            protected set;
+        }
+
+        public bool IsExpanded
+        {
+            get { return _isExpanded; }
+            set { RaiseAndSetIfChanged(ref _isExpanded, value); }
+        }
+
+        public virtual bool? IsEnabled
+        {
+            get { return _isEnabled; }
+            set { RaiseAndSetIfChanged(ref _isEnabled, value); }
+        }
+
+        public EventTreeNodeBase Parent
+        {
+            get;
+        }
+
+        public string Text
+        {
+            get;
+            private set;
+        }
+
+        internal void UpdateChecked()
+        {
+            IsEnabled = GetValue();
+
+            bool? GetValue()
+            {
+                if (Children == null)
+                    return false;
+                bool? value = false;
+                for (int i = 0; i < Children.Count; i++)
+                {
+                    if (i == 0)
+                    {
+                        value = Children[i].IsEnabled;
+                        continue;
+                    }
+
+                    if (value != Children[i].IsEnabled)
+                    {
+                        value = null;
+                        break;
+                    }
+                }
+
+                return value;
+            }
+        }
+    }
+}

src/Avalonia.Diagnostics/ViewModels/EventsViewModel.cs

@@ -0,0 +1,60 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
+using System.Collections.ObjectModel;
+using System.Globalization;
+using System.Linq;
+using System.Windows.Input;
+
+using Avalonia.Controls;
+using Avalonia.Data.Converters;
+using Avalonia.Interactivity;
+using Avalonia.Media;
+
+namespace Avalonia.Diagnostics.ViewModels
+{
+    internal class EventsViewModel : ViewModelBase
+    {
+        private readonly IControl _root;
+        private FiredEvent _selectedEvent;
+
+        public EventsViewModel(IControl root)
+        {
+            this._root = root;
+            this.Nodes = RoutedEventRegistry.Instance.GetAllRegistered()
+                .GroupBy(e => e.OwnerType)
+                .OrderBy(e => e.Key.Name)
+                .Select(g => new EventOwnerTreeNode(g.Key, g, this))
+                .ToArray();
+        }
+
+        public EventTreeNodeBase[] Nodes { get; }
+
+        public ObservableCollection<FiredEvent> RecordedEvents { get; } = new ObservableCollection<FiredEvent>();
+
+        public FiredEvent SelectedEvent
+        {
+            get => _selectedEvent;
+            set => RaiseAndSetIfChanged(ref _selectedEvent, value);
+        }
+
+        private void Clear()
+        {
+            RecordedEvents.Clear();
+        }
+    }
+
+    internal class BoolToBrushConverter : IValueConverter
+    {
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            return (bool)value ? Brushes.LightGreen : Brushes.Transparent;
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

src/Avalonia.Diagnostics/ViewModels/FiredEvent.cs

@@ -0,0 +1,80 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
+using System.Collections.ObjectModel;
+
+using Avalonia.Diagnostics.Models;
+using Avalonia.Interactivity;
+
+namespace Avalonia.Diagnostics.ViewModels
+{
+    internal class FiredEvent : ViewModelBase
+    {
+        private RoutedEventArgs _eventArgs;
+        private EventChainLink _handledBy;
+
+        public FiredEvent(RoutedEventArgs eventArgs, EventChainLink originator)
+        {
+            Contract.Requires<ArgumentNullException>(eventArgs != null);
+            Contract.Requires<ArgumentNullException>(originator != null);
+
+            this._eventArgs = eventArgs;
+            this.Originator = originator;
+            AddToChain(originator);
+        }
+
+        public bool IsPartOfSameEventChain(RoutedEventArgs e)
+        {
+            return e == _eventArgs;
+        }
+
+        public RoutedEvent Event => _eventArgs.RoutedEvent;
+
+        public bool IsHandled => HandledBy?.Handled == true;
+
+        public ObservableCollection<EventChainLink> EventChain { get; } = new ObservableCollection<EventChainLink>();
+
+        public string DisplayText
+        {
+            get
+            {
+                if (IsHandled)
+                {
+                    return $"{Event.Name} on {Originator.HandlerName};" + Environment.NewLine +
+                        $"strategies: {Event.RoutingStrategies}; handled by: {HandledBy.HandlerName}";
+                }
+                return $"{Event.Name} on {Originator.HandlerName}; strategies: {Event.RoutingStrategies}";
+            }
+        }
+
+        public EventChainLink Originator { get; }
+
+        public EventChainLink HandledBy
+        {
+            get { return _handledBy; }
+            set
+            {
+                if (_handledBy != value)
+                {
+                    _handledBy = value;
+                    RaisePropertyChanged();
+                    RaisePropertyChanged(nameof(IsHandled));
+                    RaisePropertyChanged(nameof(DisplayText));
+                }
+            }
+        }
+
+        public void AddToChain(object handler, bool handled, RoutingStrategies route)
+        {
+            AddToChain(new EventChainLink(handler, handled, route));
+        }
+
+        public void AddToChain(EventChainLink link)
+        {
+            EventChain.Add(link);
+            if (HandledBy == null && link.Handled)
+                HandledBy = link;
+        }
+    }
+}

src/Avalonia.Diagnostics/Views/EventsView.xaml

@@ -0,0 +1,53 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:vm="clr-namespace:Avalonia.Diagnostics.ViewModels">
+    <UserControl.Resources>
+        <vm:BoolToBrushConverter x:Key="boolToBrush" />
+    </UserControl.Resources>
+    <Grid ColumnDefinitions="*,4,3*">
+        <TreeView Name="tree" Items="{Binding Nodes}" SelectedItem="{Binding SelectedNode, Mode=TwoWay}" Grid.RowSpan="2">
+            <TreeView.DataTemplates>
+                <TreeDataTemplate DataType="vm:EventTreeNodeBase"
+                                  ItemsSource="{Binding Children}">
+                    <CheckBox Content="{Binding Text}" IsChecked="{Binding IsEnabled, Mode=TwoWay}" />
+                </TreeDataTemplate>
+            </TreeView.DataTemplates>
+            <TreeView.Styles>
+                <Style Selector="TreeViewItem">
+                    <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}"/>
+                </Style>
+            </TreeView.Styles>
+        </TreeView>
+                          
+        <GridSplitter Width="4" Grid.Column="1" />
+        <Grid RowDefinitions="*,4,2*,Auto" Grid.Column="2">
+            <ListBox Name="eventsList" Items="{Binding RecordedEvents}" SelectedItem="{Binding SelectedEvent, Mode=TwoWay}">
+                <ListBox.ItemTemplate>
+                    <DataTemplate>
+                        <TextBlock Background="{Binding IsHandled, Converter={StaticResource boolToBrush}}" Text="{Binding DisplayText}" />
+                    </DataTemplate>
+                </ListBox.ItemTemplate>
+            </ListBox>
+            <GridSplitter Height="4" Grid.Row="1" />
+            <DockPanel Grid.Row="2" LastChildFill="True">
+                <TextBlock DockPanel.Dock="Top" FontSize="16" Text="Event chain:" />
+                <ListBox Items="{Binding SelectedEvent.EventChain}">
+                    <ListBox.ItemTemplate>
+                        <DataTemplate>
+                            <StackPanel Orientation="Horizontal" Background="{Binding Handled, Converter={StaticResource boolToBrush}}">
+                                <TextBlock Text="{Binding Route}" />
+                                <TextBlock Text=": " />
+                                <TextBlock Text="{Binding HandlerName}" />
+                                <TextBlock Text=" handled: " />
+                                <TextBlock Text="{Binding Handled}" />
+                            </StackPanel>
+                        </DataTemplate>
+                    </ListBox.ItemTemplate>
+                </ListBox>
+            </DockPanel>
+            <StackPanel Orientation="Horizontal" Grid.Row="3">
+                <Button Content="Clear" Margin="3" Command="{Binding Clear}"  />
+            </StackPanel>
+        </Grid>
+    </Grid>
+</UserControl>

src/Avalonia.Diagnostics/Views/EventsView.xaml.cs

@@ -0,0 +1,32 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System.Linq;
+
+using Avalonia.Controls;
+using Avalonia.Diagnostics.ViewModels;
+using Avalonia.Markup.Xaml;
+
+namespace Avalonia.Diagnostics.Views
+{
+    public class EventsView : UserControl
+    {
+        private ListBox _events;
+
+        public EventsView()
+        {
+            this.InitializeComponent();
+            _events = this.FindControl<ListBox>("events");
+        }
+
+        private void RecordedEvents_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
+        {
+            _events.ScrollIntoView(_events.Items.OfType<FiredEvent>().LastOrDefault());
+        }
+
+        private void InitializeComponent()
+        {
+            AvaloniaXamlLoader.Load(this);
+        }
+    }
+}

src/Avalonia.Styling/Styling/Style.cs

@@ -111,17 +111,20 @@ namespace Avalonia.Styling
                 {
                     var subs = GetSubscriptions(control);
 
-                    foreach (var animation in Animations)
+                    if (control is Animatable animatable)
                     {
-                        IObservable<bool> obsMatch = match.ObservableResult;
+                        foreach (var animation in Animations)
-
-                        if (match.ImmediateResult == true)
                         {
-                            obsMatch = Observable.Return(true);
+                            IObservable<bool> obsMatch = match.ObservableResult;
-                        } 
 
-                        var sub = animation.Apply((Animatable)control, obsMatch);
+                            if (match.ImmediateResult == true)
-                        subs.Add(sub);
+                            {
+                                obsMatch = Observable.Return(true);
+                            }
+
+                            var sub = animation.Apply(animatable, null, obsMatch);
+                            subs.Add(sub);
+                        } 
                     }
 
                     foreach (var setter in Setters)

src/Avalonia.Visuals/Animation/RenderLoopClock.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Avalonia.Rendering;
+
+namespace Avalonia.Animation
+{
+    public class RenderLoopClock : ClockBase, IRenderLoopTask, IGlobalClock
+    {
+        protected override void Stop()
+        {
+            AvaloniaLocator.Current.GetService<IRenderLoop>().Remove(this);
+        }
+
+        bool IRenderLoopTask.NeedsUpdate => HasSubscriptions;
+
+        void IRenderLoopTask.Render()
+        {
+        }
+
+        void IRenderLoopTask.Update(TimeSpan time)
+        {
+            Pulse(time);
+        }
+    }
+}

src/Avalonia.Visuals/Animation/TransformAnimator.cs

@@ -9,10 +9,10 @@ namespace Avalonia.Animation
     /// </summary>
     public class TransformAnimator : Animator<double>
     {
-        DoubleAnimator childKeyFrames;
+        DoubleAnimator childAnimator;
 
         /// <inheritdoc/>
-        public override IDisposable Apply(Animation animation, Animatable control, IObservable<bool> obsMatch, Action onComplete)
+        public override IDisposable Apply(Animation animation, Animatable control, IClock clock, IObservable<bool> obsMatch, Action onComplete)
         {
             var ctrl = (Visual)control;
 
@@ -36,15 +36,15 @@ namespace Avalonia.Animation
 
                 var renderTransformType = ctrl.RenderTransform.GetType();
 
-                if (childKeyFrames == null)
+                if (childAnimator == null)
                 {
-                    InitializeChildKeyFrames();
+                    InitializeChildAnimator();
                 }
 
                 // It's a transform object so let's target that.
                 if (renderTransformType == Property.OwnerType)
                 {
-                    return childKeyFrames.Apply(animation, ctrl.RenderTransform, obsMatch, onComplete);
+                    return childAnimator.Apply(animation, ctrl.RenderTransform, clock ?? control.Clock, obsMatch, onComplete);
                 }
                 // It's a TransformGroup and try finding the target there.
                 else if (renderTransformType == typeof(TransformGroup))
@@ -53,7 +53,7 @@ namespace Avalonia.Animation
                     {
                         if (transform.GetType() == Property.OwnerType)
                         {
-                            return childKeyFrames.Apply(animation, transform, obsMatch, onComplete);
+                            return childAnimator.Apply(animation, transform, clock ?? control.Clock, obsMatch, onComplete);
                         }
                     }
                 }
@@ -73,16 +73,16 @@ namespace Avalonia.Animation
             return null;
         }
 
-        void InitializeChildKeyFrames()
+        void InitializeChildAnimator()
         {
-            childKeyFrames = new DoubleAnimator();
+            childAnimator = new DoubleAnimator();
 
             foreach (AnimatorKeyFrame keyframe in this)
             {
-                childKeyFrames.Add(keyframe);
+                childAnimator.Add(keyframe);
             }
 
-            childKeyFrames.Property = Property;
+            childAnimator.Property = Property;
         }
 
         /// <inheritdocs/>

src/Avalonia.Visuals/Avalonia.Visuals.csproj

@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
+    <RootNamespace>Avalonia</RootNamespace>
   </PropertyGroup>
   <ItemGroup> 
     <ProjectReference Include="..\Avalonia.Animation\Avalonia.Animation.csproj" />

src/Avalonia.Visuals/Media/Brush.cs

@@ -10,7 +10,7 @@ namespace Avalonia.Media
     /// Describes how an area is painted.
     /// </summary>
     [TypeConverter(typeof(BrushConverter))]
-    public abstract class Brush : AvaloniaObject, IBrush
+    public abstract class Brush : AvaloniaObject, IMutableBrush
     {
         /// <summary>
         /// Defines the <see cref="Opacity"/> property.
@@ -18,6 +18,9 @@ namespace Avalonia.Media
         public static readonly StyledProperty<double> OpacityProperty =
             AvaloniaProperty.Register<Brush, double>(nameof(Opacity), 1.0);
 
+        /// <inheritdoc/>
+        public event EventHandler Invalidated;
+
         /// <summary>
         /// Gets or sets the opacity of the brush.
         /// </summary>
@@ -50,5 +53,36 @@ namespace Avalonia.Media
 
             throw new FormatException($"Invalid brush string: '{s}'.");
         }
+
+        /// <inheritdoc/>
+        public abstract IBrush ToImmutable();
+
+        /// <summary>
+        /// Marks a property as affecting the brush's visual representation.
+        /// </summary>
+        /// <param name="properties">The properties.</param>
+        /// <remarks>
+        /// After a call to this method in a brush's static constructor, any change to the
+        /// property will cause the <see cref="Invalidated"/> event to be raised on the brush.
+        /// </remarks>
+        protected static void AffectsRender<T>(params AvaloniaProperty[] properties)
+            where T : Brush
+        {
+            void Invalidate(AvaloniaPropertyChangedEventArgs e)
+            {
+                (e.Sender as T)?.RaiseInvalidated(EventArgs.Empty);
+            }
+
+            foreach (var property in properties)
+            {
+                property.Changed.Subscribe(Invalidate);
+            }
+        }
+
+        /// <summary>
+        /// Raises the <see cref="Invalidated"/> event.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        protected void RaiseInvalidated(EventArgs e) => Invalidated?.Invoke(this, e);
     }
 }

src/Avalonia.Visuals/Media/GradientBrush.cs

@@ -1,7 +1,11 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
+using System;
 using System.Collections.Generic;
+using System.Collections.Specialized;
+using System.ComponentModel;
+using Avalonia.Collections;
 using Avalonia.Metadata;
 
 namespace Avalonia.Media
@@ -20,35 +24,74 @@ namespace Avalonia.Media
         /// <summary>
         /// Defines the <see cref="GradientStops"/> property.
         /// </summary>
-        public static readonly StyledProperty<IList<GradientStop>> GradientStopsProperty =
+        public static readonly StyledProperty<GradientStops> GradientStopsProperty =
-            AvaloniaProperty.Register<GradientBrush, IList<GradientStop>>(nameof(GradientStops));
+            AvaloniaProperty.Register<GradientBrush, GradientStops>(nameof(GradientStops));
+
+        private IDisposable _gradientStopsSubscription;
+
+        static GradientBrush()
+        {
+            GradientStopsProperty.Changed.Subscribe(GradientStopsChanged);
+            AffectsRender<LinearGradientBrush>(SpreadMethodProperty);
+        }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="GradientBrush"/> class.
         /// </summary>
         public GradientBrush()
         {
-            this.GradientStops = new List<GradientStop>();
+            this.GradientStops = new GradientStops();
         }
 
-        /// <summary>
+        /// <inheritdoc/>
-        /// Gets or sets the brush's spread method that defines how to draw a gradient that
-        /// doesn't fill the bounds of the destination control.
-        /// </summary>
         public GradientSpreadMethod SpreadMethod
         {
             get { return GetValue(SpreadMethodProperty); }
             set { SetValue(SpreadMethodProperty, value); }
         }
 
-        /// <summary>
+        /// <inheritdoc/>
-        /// Gets or sets the brush's gradient stops.
-        /// </summary>
         [Content]
-        public IList<GradientStop> GradientStops
+        public GradientStops GradientStops
         {
             get { return GetValue(GradientStopsProperty); }
             set { SetValue(GradientStopsProperty, value); }
         }
+
+        /// <inheritdoc/>
+        IReadOnlyList<IGradientStop> IGradientBrush.GradientStops => GradientStops;
+
+        private static void GradientStopsChanged(AvaloniaPropertyChangedEventArgs e)
+        {
+            if (e.Sender is GradientBrush brush)
+            {
+                var oldValue = (GradientStops)e.OldValue;
+                var newValue = (GradientStops)e.NewValue;
+
+                if (oldValue != null)
+                {
+                    oldValue.CollectionChanged -= brush.GradientStopsChanged;
+                    brush._gradientStopsSubscription.Dispose();
+                }
+
+                if (newValue != null)
+                {
+                    newValue.CollectionChanged += brush.GradientStopsChanged;
+                    brush._gradientStopsSubscription = newValue.TrackItemPropertyChanged(brush.GradientStopChanged);
+                }
+
+                brush.RaiseInvalidated(EventArgs.Empty);
+            }
+        }
+
+        private void GradientStopsChanged(object sender, NotifyCollectionChangedEventArgs e)
+        {
+            RaiseInvalidated(EventArgs.Empty);
+        }
+
+        private void GradientStopChanged(Tuple<object, PropertyChangedEventArgs> e)
+        {
+            RaiseInvalidated(EventArgs.Empty);
+        }
     }
 }

src/Avalonia.Visuals/Media/GradientStop.cs

@@ -4,10 +4,22 @@
 namespace Avalonia.Media
 {
     /// <summary>
-    /// GradientStop
+    /// Describes the location and color of a transition point in a gradient.
     /// </summary>
-    public sealed class GradientStop
+    public sealed class GradientStop : AvaloniaObject, IGradientStop
     {
+        /// <summary>
+        /// Describes the <see cref="Offset"/> property.
+        /// </summary>
+        public static StyledProperty<double> OffsetProperty =
+            AvaloniaProperty.Register<GradientStop, double>(nameof(Offset));
+
+        /// <summary>
+        /// Describes the <see cref="Color"/> property.
+        /// </summary>
+        public static StyledProperty<Color> ColorProperty =
+            AvaloniaProperty.Register<GradientStop, Color>(nameof(Color));
+
         /// <summary>
         /// Initializes a new instance of the <see cref="GradientStop"/> class.
         /// </summary>
@@ -24,16 +36,18 @@ namespace Avalonia.Media
             Offset = offset;
         }
 
-        // TODO: Make these dependency properties.
+        /// <inheritdoc/>
-
+        public double Offset
-        /// <summary>
+        {
-        /// The offset
+            get => GetValue(OffsetProperty);
-        /// </summary>
+            set => SetValue(OffsetProperty, value);
-        public double Offset { get; set; }
+        }
 
-        /// <summary>
+        /// <inheritdoc/>
-        /// The color
+        public Color Color
-        /// </summary>
+        {
-        public Color Color { get; set; }
+            get => GetValue(ColorProperty);
+            set => SetValue(ColorProperty, value);
+        }
     }
-}
+}

src/Avalonia.Visuals/Media/GradientStops.cs

@@ -0,0 +1,23 @@
+using System.Collections.Generic;
+using System.Linq;
+using Avalonia.Collections;
+using Avalonia.Media.Immutable;
+
+namespace Avalonia.Media
+{
+    /// <summary>
+    /// A collection of <see cref="GradientStop"/>s.
+    /// </summary>
+    public class GradientStops : AvaloniaList<GradientStop>
+    {
+        public GradientStops()
+        {
+            ResetBehavior = ResetBehavior.Remove;
+        }
+
+        public IReadOnlyList<ImmutableGradientStop> ToImmutable()
+        {
+            return this.Select(x => new ImmutableGradientStop(x.Offset, x.Color)).ToList();
+        }
+    }
+}

src/Avalonia.Visuals/Media/IAffectsRender.cs

@@ -0,0 +1,16 @@
+using System;
+
+namespace Avalonia.Media
+{
+    /// <summary>
+    /// Signals to a self-rendering control that changes to the resource should invoke
+    /// <see cref="Visual.InvalidateVisual"/>.
+    /// </summary>
+    public interface IAffectsRender
+    {
+        /// <summary>
+        /// Raised when the resource changes visually.
+        /// </summary>
+        event EventHandler Invalidated;
+    }
+}

src/Avalonia.Visuals/Media/IGradientBrush.cs

@@ -10,7 +10,7 @@ namespace Avalonia.Media
         /// <summary>
         /// Gets the brush's gradient stops.
         /// </summary>
-        IList<GradientStop> GradientStops { get; }
+        IReadOnlyList<IGradientStop> GradientStops { get; }
 
         /// <summary>
         /// Gets the brush's spread method that defines how to draw a gradient that doesn't fill
@@ -18,4 +18,4 @@ namespace Avalonia.Media
         /// </summary>
         GradientSpreadMethod SpreadMethod { get; }
     }
-}
+}

src/Avalonia.Visuals/Media/IGradientStop.cs

@@ -0,0 +1,18 @@
+namespace Avalonia.Media
+{
+    /// <summary>
+    /// Describes the location and color of a transition point in a gradient.
+    /// </summary>
+    public interface IGradientStop
+    {
+        /// <summary>
+        /// Gets the gradient stop color.
+        /// </summary>
+        Color Color { get; }
+
+        /// <summary>
+        /// Gets the gradient stop offset.
+        /// </summary>
+        double Offset { get; }
+    }
+}

src/Avalonia.Visuals/Media/IMutableBrush.cs

@@ -1,9 +1,11 @@
-namespace Avalonia.Media
+using System;
+
+namespace Avalonia.Media
 {
     /// <summary>
     /// Represents a mutable brush which can return an immutable clone of itself.
     /// </summary>
-    public interface IMutableBrush : IBrush
+    public interface IMutableBrush : IBrush, IAffectsRender
     {
         /// <summary>
         /// Creates an immutable clone of the brush.

src/Avalonia.Visuals/Media/ImageBrush.cs

@@ -2,13 +2,14 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using Avalonia.Media.Imaging;
+using Avalonia.Media.Immutable;
 
 namespace Avalonia.Media
 {
     /// <summary>
     /// Paints an area with an <see cref="IBitmap"/>.
     /// </summary>
-    public class ImageBrush : TileBrush, IImageBrush, IMutableBrush
+    public class ImageBrush : TileBrush, IImageBrush
     {
         /// <summary>
         /// Defines the <see cref="Visual"/> property.
@@ -16,6 +17,11 @@ namespace Avalonia.Media
         public static readonly StyledProperty<IBitmap> SourceProperty =
             AvaloniaProperty.Register<ImageBrush, IBitmap>(nameof(Source));
 
+        static ImageBrush()
+        {
+            AffectsRender<ImageBrush>(SourceProperty);
+        }
+
         /// <summary>
         /// Initializes a new instance of the <see cref="ImageBrush"/> class.
         /// </summary>
@@ -42,9 +48,9 @@ namespace Avalonia.Media
         }
 
         /// <inheritdoc/>
-        IBrush IMutableBrush.ToImmutable()
+        public override IBrush ToImmutable()
         {
-            return new Immutable.ImmutableImageBrush(this);
+            return new ImmutableImageBrush(this);
         }
     }
 }

src/Avalonia.Visuals/Media/Immutable/ImmutableGradientBrush.cs

@@ -1,5 +1,4 @@
 using System.Collections.Generic;
-using System.Linq;
 
 namespace Avalonia.Media.Immutable
 {
@@ -15,7 +14,7 @@ namespace Avalonia.Media.Immutable
         /// <param name="opacity">The opacity of the brush.</param>
         /// <param name="spreadMethod">The spread method.</param>
         protected ImmutableGradientBrush(
-            IList<GradientStop> gradientStops,
+            IReadOnlyList<ImmutableGradientStop> gradientStops,
             double opacity,
             GradientSpreadMethod spreadMethod)
         {
@@ -28,14 +27,14 @@ namespace Avalonia.Media.Immutable
         /// Initializes a new instance of the <see cref="ImmutableGradientBrush"/> class.
         /// </summary>
         /// <param name="source">The brush from which this brush's properties should be copied.</param>
-        protected ImmutableGradientBrush(IGradientBrush source)
+        protected ImmutableGradientBrush(GradientBrush source)
-            : this(source.GradientStops.ToList(), source.Opacity, source.SpreadMethod)
+            : this(source.GradientStops.ToImmutable(), source.Opacity, source.SpreadMethod)
         {
 
         }
 
         /// <inheritdoc/>
-        public IList<GradientStop> GradientStops { get; }
+        public IReadOnlyList<IGradientStop> GradientStops { get; }
 
         /// <inheritdoc/>
         public double Opacity { get; }

src/Avalonia.Visuals/Media/Immutable/ImmutableGradientStop.cs

@@ -0,0 +1,20 @@
+namespace Avalonia.Media.Immutable
+{
+    /// <summary>
+    /// Describes the location and color of a transition point in a gradient.
+    /// </summary>
+    public class ImmutableGradientStop : IGradientStop
+    {
+        public ImmutableGradientStop(double offset, Color color)
+        {
+            Offset = offset;
+            Color = color;
+        }
+
+        /// <inheritdoc/>
+        public double Offset { get; }
+
+        /// <inheritdoc/>
+        public Color Color { get; }
+    }
+}

src/Avalonia.Visuals/Media/Immutable/ImmutableLinearGradientBrush.cs

@@ -16,7 +16,7 @@ namespace Avalonia.Media.Immutable
         /// <param name="startPoint">The start point for the gradient.</param>
         /// <param name="endPoint">The end point for the gradient.</param>
         public ImmutableLinearGradientBrush(
-            IList<GradientStop> gradientStops,
+            IReadOnlyList<ImmutableGradientStop> gradientStops,
             double opacity = 1,
             GradientSpreadMethod spreadMethod = GradientSpreadMethod.Pad,
             RelativePoint? startPoint = null,
@@ -31,7 +31,7 @@ namespace Avalonia.Media.Immutable
         /// Initializes a new instance of the <see cref="ImmutableLinearGradientBrush"/> class.
         /// </summary>
         /// <param name="source">The brush from which this brush's properties should be copied.</param>
-        public ImmutableLinearGradientBrush(ILinearGradientBrush source)
+        public ImmutableLinearGradientBrush(LinearGradientBrush source)
             : base(source)
         {
             StartPoint = source.StartPoint;

src/Avalonia.Visuals/Media/Immutable/ImmutableRadialGradientBrush.cs

@@ -21,7 +21,7 @@ namespace Avalonia.Media.Immutable
         /// The horizontal and vertical radius of the outermost circle of the radial gradient.
         /// </param>
         public ImmutableRadialGradientBrush(
-            IList<GradientStop> gradientStops,
+            IReadOnlyList<ImmutableGradientStop> gradientStops,
             double opacity = 1,
             GradientSpreadMethod spreadMethod = GradientSpreadMethod.Pad,
             RelativePoint? center = null,
@@ -38,7 +38,7 @@ namespace Avalonia.Media.Immutable
         /// Initializes a new instance of the <see cref="ImmutableRadialGradientBrush"/> class.
         /// </summary>
         /// <param name="source">The brush from which this brush's properties should be copied.</param>
-        public ImmutableRadialGradientBrush(IRadialGradientBrush source)
+        public ImmutableRadialGradientBrush(RadialGradientBrush source)
             : base(source)
         {
             Center = source.Center;

src/Avalonia.Visuals/Media/LinearGradientBrush.cs

@@ -1,12 +1,14 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
+using Avalonia.Media.Immutable;
+
 namespace Avalonia.Media
 {
     /// <summary>
     /// A brush that draws with a linear gradient.
     /// </summary>
-    public sealed class LinearGradientBrush : GradientBrush, ILinearGradientBrush, IMutableBrush
+    public sealed class LinearGradientBrush : GradientBrush, ILinearGradientBrush
     {
         /// <summary>
         /// Defines the <see cref="StartPoint"/> property.
@@ -24,6 +26,11 @@ namespace Avalonia.Media
                 nameof(EndPoint), 
                 RelativePoint.BottomRight);
 
+        static LinearGradientBrush()
+        {
+            AffectsRender<LinearGradientBrush>(StartPointProperty, EndPointProperty);
+        }
+
         /// <summary>
         /// Gets or sets the start point for the gradient.
         /// </summary>
@@ -43,9 +50,9 @@ namespace Avalonia.Media
         }
 
         /// <inheritdoc/>
-        IBrush IMutableBrush.ToImmutable()
+        public override IBrush ToImmutable()
         {
-            return new Immutable.ImmutableLinearGradientBrush(this);
+            return new ImmutableLinearGradientBrush(this);
         }
     }
 }

src/Avalonia.Visuals/Media/RadialGradientBrush.cs

@@ -1,12 +1,14 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
+using Avalonia.Media.Immutable;
+
 namespace Avalonia.Media
 {
     /// <summary>
     /// Paints an area with a radial gradient.
     /// </summary>
-    public sealed class RadialGradientBrush : GradientBrush, IRadialGradientBrush, IMutableBrush
+    public sealed class RadialGradientBrush : GradientBrush, IRadialGradientBrush
     {
         /// <summary>
         /// Defines the <see cref="Center"/> property.
@@ -63,9 +65,9 @@ namespace Avalonia.Media
         }
 
         /// <inheritdoc/>
-        IBrush IMutableBrush.ToImmutable()
+        public override IBrush ToImmutable()
         {
-            return new Immutable.ImmutableRadialGradientBrush(this);
+            return new ImmutableRadialGradientBrush(this);
         }
     }
-}
+}

src/Avalonia.Visuals/Media/SolidColorBrush.cs

@@ -1,12 +1,14 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
+using Avalonia.Media.Immutable;
+
 namespace Avalonia.Media
 {
     /// <summary>
     /// Fills an area with a solid color.
     /// </summary>
-    public class SolidColorBrush : Brush, ISolidColorBrush, IMutableBrush
+    public class SolidColorBrush : Brush, ISolidColorBrush
     {
         /// <summary>
         /// Defines the <see cref="Color"/> property.
@@ -14,6 +16,11 @@ namespace Avalonia.Media
         public static readonly StyledProperty<Color> ColorProperty =
             AvaloniaProperty.Register<SolidColorBrush, Color>(nameof(Color));
 
+        static SolidColorBrush()
+        {
+            AffectsRender<SolidColorBrush>(ColorProperty);
+        }
+
         /// <summary>
         /// Initializes a new instance of the <see cref="SolidColorBrush"/> class.
         /// </summary>
@@ -75,9 +82,9 @@ namespace Avalonia.Media
         }
 
         /// <inheritdoc/>
-        IBrush IMutableBrush.ToImmutable()
+        public override IBrush ToImmutable()
         {
-            return new Immutable.ImmutableSolidColorBrush(this);
+            return new ImmutableSolidColorBrush(this);
         }
     }
 }

src/Avalonia.Visuals/Media/TileBrush.cs

@@ -79,6 +79,13 @@ namespace Avalonia.Media
 
         static TileBrush()
         {
+            AffectsRender<TileBrush>(
+                AlignmentXProperty,
+                AlignmentYProperty,
+                DestinationRectProperty,
+                SourceRectProperty,
+                StretchProperty,
+                TileModeProperty);
             RenderOptions.BitmapInterpolationModeProperty.OverrideDefaultValue<TileBrush>(BitmapInterpolationMode.Default);
         }
 

src/Avalonia.Visuals/Media/VisualBrush.cs

@@ -1,6 +1,7 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
+using Avalonia.Media.Immutable;
 using Avalonia.VisualTree;
 
 namespace Avalonia.Media
@@ -8,7 +9,7 @@ namespace Avalonia.Media
     /// <summary>
     /// Paints an area with an <see cref="IVisual"/>.
     /// </summary>
-    public class VisualBrush : TileBrush, IVisualBrush, IMutableBrush
+    public class VisualBrush : TileBrush, IVisualBrush
     {
         /// <summary>
         /// Defines the <see cref="Visual"/> property.
@@ -16,6 +17,11 @@ namespace Avalonia.Media
         public static readonly StyledProperty<IVisual> VisualProperty =
             AvaloniaProperty.Register<VisualBrush, IVisual>(nameof(Visual));
 
+        static VisualBrush()
+        {
+            AffectsRender<VisualBrush>(VisualProperty);
+        }
+
         /// <summary>
         /// Initializes a new instance of the <see cref="VisualBrush"/> class.
         /// </summary>
@@ -42,9 +48,9 @@ namespace Avalonia.Media
         }
 
         /// <inheritdoc/>
-        IBrush IMutableBrush.ToImmutable()
+        public override IBrush ToImmutable()
         {
-            return new Immutable.ImmutableVisualBrush(this);
+            return new ImmutableVisualBrush(this);
         }
     }
 }

src/Avalonia.Visuals/Rendering/DefaultRenderLoop.cs → src/Avalonia.Visuals/Rendering/DefaultRenderTimer.cs

@@ -2,31 +2,33 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using System;
+using System.Diagnostics;
+using System.Threading.Tasks;
 using Avalonia.Platform;
 
 namespace Avalonia.Rendering
 {
     /// <summary>
-    /// Defines a default render loop that uses a standard timer.
+    /// Defines a default render timer that uses a standard timer.
     /// </summary>
     /// <remarks>
     /// This class may be overridden by platform implementations to use a specialized timer
     /// implementation.
     /// </remarks>
-    public class DefaultRenderLoop : IRenderLoop
+    public class DefaultRenderTimer : IRenderTimer
     {
         private IRuntimePlatform _runtime;
         private int _subscriberCount;
-        private EventHandler<EventArgs> _tick;
+        private Action<TimeSpan> _tick;
         private IDisposable _subscription;
 
         /// <summary>
-        /// Initializes a new instance of the <see cref="DefaultRenderLoop"/> class.
+        /// Initializes a new instance of the <see cref="DefaultRenderTimer"/> class.
         /// </summary>
         /// <param name="framesPerSecond">
         /// The number of frames per second at which the loop should run.
         /// </param>
-        public DefaultRenderLoop(int framesPerSecond)
+        public DefaultRenderTimer(int framesPerSecond)
         {
             FramesPerSecond = framesPerSecond;
         }
@@ -37,7 +39,7 @@ namespace Avalonia.Rendering
         public int FramesPerSecond { get; }
 
         /// <inheritdoc/>
-        public event EventHandler<EventArgs> Tick
+        public event Action<TimeSpan> Tick
         {
             add
             {
@@ -76,14 +78,16 @@ namespace Avalonia.Rendering
         /// This can be overridden by platform implementations to use a specialized timer
         /// implementation.
         /// </remarks>
-        protected virtual IDisposable StartCore(Action tick)
+        protected virtual IDisposable StartCore(Action<TimeSpan> tick)
         {
             if (_runtime == null)
             {
                 _runtime = AvaloniaLocator.Current.GetService<IRuntimePlatform>();
             }
 
-            return _runtime.StartSystemTimer(TimeSpan.FromSeconds(1.0 / FramesPerSecond), tick);
+            return _runtime.StartSystemTimer(
+                TimeSpan.FromSeconds(1.0 / FramesPerSecond),
+                () => tick(TimeSpan.FromMilliseconds(Environment.TickCount)));
         }
 
         /// <summary>
@@ -95,9 +99,9 @@ namespace Avalonia.Rendering
             _subscription = null;
         }
 
-        private void InternalTick()
+        private void InternalTick(TimeSpan tickCount)
         {
-            _tick(this, EventArgs.Empty);
+            _tick(tickCount);
         }
     }
 }

src/Avalonia.Visuals/Rendering/DeferredRenderer.cs

@@ -13,6 +13,7 @@ using Avalonia.Rendering.SceneGraph;
 using Avalonia.Threading;
 using Avalonia.Utilities;
 using Avalonia.VisualTree;
+using System.Threading.Tasks;
 
 namespace Avalonia.Rendering
 {
@@ -20,7 +21,7 @@ namespace Avalonia.Rendering
     /// A renderer which renders the state of the visual tree to an intermediate scene graph
     /// representation which is then rendered on a rendering thread.
     /// </summary>
-    public class DeferredRenderer : RendererBase, IRenderer, IVisualBrushRenderer
+    public class DeferredRenderer : RendererBase, IRenderer, IRenderLoopTask, IVisualBrushRenderer
     {
         private readonly IDispatcher _dispatcher;
         private readonly IRenderLoop _renderLoop;
@@ -31,7 +32,6 @@ namespace Avalonia.Rendering
         private volatile IRef<Scene> _scene;
         private DirtyVisuals _dirty;
         private IRef<IRenderTargetBitmapImpl> _overlay;
-        private bool _updateQueued;
         private object _rendering = new object();
         private int _lastSceneId = -1;
         private DisplayDirtyRects _dirtyRectsDisplay = new DisplayDirtyRects();
@@ -149,7 +149,7 @@ namespace Avalonia.Rendering
         {
             if (!_running && _renderLoop != null)
             {
-                _renderLoop.Tick += OnRenderLoopTick;
+                _renderLoop.Add(this);
                 _running = true;
             }
         }
@@ -159,11 +159,23 @@ namespace Avalonia.Rendering
         {
             if (_running && _renderLoop != null)
             {
-                _renderLoop.Tick -= OnRenderLoopTick;
+                _renderLoop.Remove(this);
                 _running = false;
             }
         }
 
+        bool IRenderLoopTask.NeedsUpdate => _dirty == null || _dirty.Count > 0;
+
+        void IRenderLoopTask.Update(TimeSpan time) => UpdateScene();
+
+        void IRenderLoopTask.Render()
+        {
+            using (var scene = _scene?.Clone())
+            {
+                Render(scene?.Item);
+            }
+        }
+
         /// <inheritdoc/>
         Size IVisualBrushRenderer.GetRenderTargetSize(IVisualBrush brush)
         {
@@ -381,67 +393,34 @@ namespace Avalonia.Rendering
         private void UpdateScene()
         {
             Dispatcher.UIThread.VerifyAccess();
-
+            if (_root.IsVisible)
-            try
             {
-                if (_root.IsVisible)
+                var sceneRef = RefCountable.Create(_scene?.Item.CloneScene() ?? new Scene(_root));
-                {
+                var scene = sceneRef.Item;
-                    var sceneRef = RefCountable.Create(_scene?.Item.CloneScene() ?? new Scene(_root));
-                    var scene = sceneRef.Item;
-
-                    if (_dirty == null)
-                    {
-                        _dirty = new DirtyVisuals();
-                        _sceneBuilder.UpdateAll(scene);
-                    }
-                    else if (_dirty.Count > 0)
-                    {
-                        foreach (var visual in _dirty)
-                        {
-                            _sceneBuilder.Update(scene, visual);
-                        }
-                    }
-
-                    var oldScene = Interlocked.Exchange(ref _scene, sceneRef);
-                    oldScene?.Dispose();
 
-                    _dirty.Clear();
+                if (_dirty == null)
-                    (_root as IRenderRoot)?.Invalidate(new Rect(scene.Size));
-                }
-                else
                 {
-                    var oldScene = Interlocked.Exchange(ref _scene, null);
+                    _dirty = new DirtyVisuals();
-                    oldScene?.Dispose();
+                    _sceneBuilder.UpdateAll(scene);
                 }
-            }
+                else if (_dirty.Count > 0)
-            finally
-            {
-                _updateQueued = false;
-            }
-        }
-
-        private void OnRenderLoopTick(object sender, EventArgs e)
-        {
-            if (Monitor.TryEnter(_rendering))
-            {
-                try
                 {
-                    if (!_updateQueued && (_dirty == null || _dirty.Count > 0))
+                    foreach (var visual in _dirty)
                     {
-                        _updateQueued = true;
+                        _sceneBuilder.Update(scene, visual);
-                        _dispatcher.Post(UpdateScene, DispatcherPriority.Render);
-                    }
-                    
-                    using (var scene = _scene?.Clone())
-                    {
-                        Render(scene?.Item);
                     }
                 }
-                catch { }
+
-                finally
+                var oldScene = Interlocked.Exchange(ref _scene, sceneRef);
-                {
+                oldScene?.Dispose();
-                    Monitor.Exit(_rendering);
+
-                }
+                _dirty.Clear();
+                (_root as IRenderRoot)?.Invalidate(new Rect(scene.Size));
+            }
+            else
+            {
+                var oldScene = Interlocked.Exchange(ref _scene, null);
+                oldScene?.Dispose();
             }
         }
 

src/Avalonia.Visuals/Rendering/ICustomSimpleHitTest.cs

@@ -0,0 +1,12 @@
+namespace Avalonia.Rendering
+{
+    /// <summary>
+    /// An interface to allow non-templated controls to customize their hit-testing
+    /// when using a renderer with a simple hit-testing algorithm without a scene graph,
+    /// such as <see cref="ImmediateRenderer" />
+    /// </summary>
+    public interface ICustomSimpleHitTest
+    {
+        bool HitTest(Point point);
+    }
+}

src/Avalonia.Visuals/Rendering/IRenderLoop.cs

@@ -1,19 +1,28 @@
-using System;
+namespace Avalonia.Rendering
-
-namespace Avalonia.Rendering
 {
     /// <summary>
-    /// Defines the interface implemented by an application render loop.
+    /// The application render loop.
     /// </summary>
+    /// <remarks>
+    /// The render loop is responsible for advancing the animation timer and updating the scene
+    /// graph for visible windows.
+    /// </remarks>
     public interface IRenderLoop
     {
         /// <summary>
-        /// Raised when the render loop ticks to signal a new frame should be drawn.
+        /// Adds an update task.
         /// </summary>
+        /// <param name="i">The update task.</param>
         /// <remarks>
-        /// This event can be raised on any thread; it is the responsibility of the subscriber to
+        /// Registered update tasks will be polled on each tick of the render loop after the
-        /// switch execution to the right thread.
+        /// animation timer has been pulsed.
         /// </remarks>
-        event EventHandler<EventArgs> Tick;
+        void Add(IRenderLoopTask i);
+
+        /// <summary>
+        /// Removes an update task.
+        /// </summary>
+        /// <param name="i">The update task.</param>
+        void Remove(IRenderLoopTask i);
     }
-}
+}

src/Avalonia.Visuals/Rendering/IRenderLoopTask.cs

@@ -0,0 +1,12 @@
+using System;
+using System.Threading.Tasks;
+
+namespace Avalonia.Rendering
+{
+    public interface IRenderLoopTask
+    {
+        bool NeedsUpdate { get; }
+        void Update(TimeSpan time);
+        void Render();
+    }
+}

src/Avalonia.Visuals/Rendering/IRenderTimer.cs

@@ -0,0 +1,20 @@
+using System;
+using System.Threading.Tasks;
+
+namespace Avalonia.Rendering
+{
+    /// <summary>
+    /// Defines the interface implemented by an application render timer.
+    /// </summary>
+    public interface IRenderTimer
+    {
+        /// <summary>
+        /// Raised when the render timer ticks to signal a new frame should be drawn.
+        /// </summary>
+        /// <remarks>
+        /// This event can be raised on any thread; it is the responsibility of the subscriber to
+        /// switch execution to the right thread.
+        /// </remarks>
+        event Action<TimeSpan> Tick;
+    }
+}

src/Avalonia.Visuals/Rendering/ImmediateRenderer.cs

@@ -200,7 +200,16 @@ namespace Avalonia.Rendering
 
             if (filter?.Invoke(visual) != false)
             {
-                bool containsPoint = visual.TransformedBounds?.Contains(p) == true;
+                bool containsPoint = false;
+
+                if (visual is ICustomSimpleHitTest custom)
+                {
+                    containsPoint = custom.HitTest(p);
+                }
+                else
+                {
+                    containsPoint = visual.TransformedBounds?.Contains(p) == true;
+                }
 
                 if ((containsPoint || !visual.ClipToBounds) && visual.VisualChildren.Count > 0)
                 {

src/Avalonia.Visuals/Rendering/RenderLoop.cs

@@ -0,0 +1,120 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using Avalonia.Logging;
+using Avalonia.Threading;
+
+namespace Avalonia.Rendering
+{
+    /// <summary>
+    /// The application render loop.
+    /// </summary>
+    /// <remarks>
+    /// The render loop is responsible for advancing the animation timer and updating the scene
+    /// graph for visible windows.
+    /// </remarks>
+    public class RenderLoop : IRenderLoop
+    {
+        private readonly IDispatcher _dispatcher;
+        private List<IRenderLoopTask> _items = new List<IRenderLoopTask>();
+        private IRenderTimer _timer;
+        private int inTick;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="RenderLoop"/> class.
+        /// </summary>
+        public RenderLoop()
+        {
+            _dispatcher = Dispatcher.UIThread;
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="RenderLoop"/> class.
+        /// </summary>
+        /// <param name="timer">The render timer.</param>
+        /// <param name="dispatcher">The UI thread dispatcher.</param>
+        public RenderLoop(IRenderTimer timer, IDispatcher dispatcher)
+        {
+            _timer = timer;
+            _dispatcher = dispatcher;
+        }
+
+        /// <summary>
+        /// Gets the render timer.
+        /// </summary>
+        protected IRenderTimer Timer
+        {
+            get
+            {
+                if (_timer == null)
+                {
+                    _timer = AvaloniaLocator.Current.GetService<IRenderTimer>();
+                }
+
+                return _timer;
+            }
+        }
+
+        /// <inheritdoc/>
+        public void Add(IRenderLoopTask i)
+        {
+            Contract.Requires<ArgumentNullException>(i != null);
+            Dispatcher.UIThread.VerifyAccess();
+
+            _items.Add(i);
+
+            if (_items.Count == 1)
+            {
+                Timer.Tick += TimerTick;
+            }
+        }
+
+        /// <inheritdoc/>
+        public void Remove(IRenderLoopTask i)
+        {
+            Contract.Requires<ArgumentNullException>(i != null);
+            Dispatcher.UIThread.VerifyAccess();
+
+            _items.Remove(i);
+
+            if (_items.Count == 0)
+            {
+                Timer.Tick -= TimerTick;
+            }
+        }
+
+        private async void TimerTick(TimeSpan time)
+        {
+            if (Interlocked.CompareExchange(ref inTick, 1, 0) == 0)
+            {
+                try
+                {
+                    if (_items.Any(item => item.NeedsUpdate))
+                    {
+                        await _dispatcher.InvokeAsync(() =>
+                        {
+                            foreach (var i in _items)
+                            {
+                                i.Update(time);
+                            }
+                        }, DispatcherPriority.Render).ConfigureAwait(false);
+                    }
+
+                    foreach (var i in _items)
+                    {
+                        i.Render();
+                    }
+                }
+                catch (Exception ex)
+                {
+                    Logger.Error(LogArea.Visual, this, "Exception in render loop: {Error}", ex);
+                }
+                finally
+                {
+                    Interlocked.Exchange(ref inTick, 0);
+                }
+            }
+        }
+    }
+}

src/Avalonia.Visuals/Visual.cs

@@ -338,11 +338,24 @@ namespace Avalonia
         /// FrameworkPropertyMetadata.AffectsRender flag.
         /// </remarks>
         protected static void AffectsRender<T>(params AvaloniaProperty[] properties)
-            where T : class, IVisual
+            where T : Visual
         {
             void Invalidate(AvaloniaPropertyChangedEventArgs e)
             {
-                (e.Sender as T)?.InvalidateVisual();
+                if (e.Sender is T sender)
+                {
+                    if (e.OldValue is IAffectsRender oldValue)
+                    {
+                        oldValue.Invalidated -= sender.AffectsRenderInvalidated;
+                    }
+
+                    if (e.NewValue is IAffectsRender newValue)
+                    {
+                        newValue.Invalidated += sender.AffectsRenderInvalidated;
+                    }
+
+                    sender.InvalidateVisual();
+                }
             }
 
             foreach (var property in properties)
@@ -544,6 +557,8 @@ namespace Avalonia
             OnVisualParentChanged(old, value);
         }
 
+        private void AffectsRenderInvalidated(object sender, EventArgs e) => InvalidateVisual();
+
         /// <summary>
         /// Called when the <see cref="VisualChildren"/> collection changes.
         /// </summary>

src/Gtk/Avalonia.Gtk3/Gtk3Platform.cs

@@ -52,7 +52,8 @@ namespace Avalonia.Gtk3
                 .Bind<IPlatformSettings>().ToConstant(Instance)
                 .Bind<IPlatformThreadingInterface>().ToConstant(Instance)
                 .Bind<ISystemDialogImpl>().ToSingleton<SystemDialog>()
-                .Bind<IRenderLoop>().ToConstant(new DefaultRenderLoop(60))
+                .Bind<IRenderLoop>().ToConstant(new RenderLoop())
+                .Bind<IRenderTimer>().ToConstant(new DefaultRenderTimer(60))
                 .Bind<IPlatformIconLoader>().ToConstant(new PlatformIconLoader());
 
         }

src/Linux/Avalonia.LinuxFramebuffer/LinuxFramebufferPlatform.cs

@@ -35,7 +35,8 @@ namespace Avalonia.LinuxFramebuffer
                 .Bind<IKeyboardDevice>().ToConstant(KeyboardDevice)
                 .Bind<IPlatformSettings>().ToSingleton<PlatformSettings>()
                 .Bind<IPlatformThreadingInterface>().ToConstant(Threading)
-                .Bind<IRenderLoop>().ToConstant(Threading);
+                .Bind<IRenderLoop>().ToConstant(new RenderLoop())
+                .Bind<IRenderTimer>().ToConstant(Threading);
         }
 
         internal static TopLevel Initialize<T>(T builder, string fbdev = null) where T : AppBuilderBase<T>, new()

src/OSX/Avalonia.MonoMac/MonoMacPlatform.cs

@@ -21,6 +21,7 @@ namespace Avalonia.MonoMac
         private static bool s_monoMacInitialized;
         private static bool s_showInDock = true;
         private static IRenderLoop s_renderLoop;
+        private static IRenderTimer s_renderTimer;
 
         void DoInitialize()
         {
@@ -35,6 +36,7 @@ namespace Avalonia.MonoMac
                 .Bind<ISystemDialogImpl>().ToSingleton<SystemDialogsImpl>()
                 .Bind<IClipboard>().ToSingleton<ClipboardImpl>()
                 .Bind<IRenderLoop>().ToConstant(s_renderLoop)
+                .Bind<IRenderTimer>().ToConstant(s_renderTimer)
                 .Bind<IPlatformThreadingInterface>().ToConstant(PlatformThreadingInterface.Instance)
                 /*.Bind<IPlatformDragSource>().ToTransient<DragSource>()*/;
         }
@@ -83,7 +85,8 @@ namespace Avalonia.MonoMac
             ThreadHelper.InitializeCocoaThreadingLocks();
             App = NSApplication.SharedApplication;
             UpdateActivationPolicy();
-            s_renderLoop = new RenderLoop(); //TODO: use CVDisplayLink
+            s_renderLoop = new RenderLoop();
+            s_renderTimer = new RenderTimer(60); //TODO: use CVDisplayLink
             s_monoMacInitialized = true;
         }
 
@@ -133,4 +136,4 @@ namespace Avalonia
             return builder.UseWindowingSubsystem(MonoMac.MonoMacPlatform.Initialize, "MonoMac");
         }
     }
-}
+}

src/OSX/Avalonia.MonoMac/RenderLoop.cs

@@ -1,31 +0,0 @@
-using System;
-using Avalonia.Platform;
-using Avalonia.Rendering;
-using MonoMac.Foundation;
-
-namespace Avalonia.MonoMac
-{
-    //TODO: Switch to using CVDisplayLink
-    public class RenderLoop : IRenderLoop
-    {
-        private readonly object _lock = new object();
-        private readonly IDisposable _timer;
-
-        public RenderLoop()
-        {
-            _timer = AvaloniaLocator.Current.GetService<IRuntimePlatform>().StartSystemTimer(new TimeSpan(0, 0, 0, 0, 1000 / 60),
-                () =>
-                {
-                    lock (_lock)
-                    {
-                        using (new NSAutoreleasePool())
-                        {
-                            Tick?.Invoke(this, EventArgs.Empty);
-                        }
-                    }
-                });
-        }
-
-        public event EventHandler<EventArgs> Tick;
-    }
-}

src/OSX/Avalonia.MonoMac/RenderTimer.cs

@@ -0,0 +1,28 @@
+using System;
+using Avalonia.Platform;
+using Avalonia.Rendering;
+using MonoMac.Foundation;
+
+namespace Avalonia.MonoMac
+{
+    //TODO: Switch to using CVDisplayLink
+    public class RenderTimer : DefaultRenderTimer
+    {
+        public RenderTimer(int framesPerSecond) : base(framesPerSecond)
+        {
+        }
+
+        protected override IDisposable StartCore(Action<TimeSpan> tick)
+        {
+            return AvaloniaLocator.Current.GetService<IRuntimePlatform>().StartSystemTimer(
+                TimeSpan.FromSeconds(1.0 / FramesPerSecond),
+                () =>
+                {
+                    using (new NSAutoreleasePool())
+                    {
+                        tick?.Invoke(TimeSpan.FromMilliseconds(Environment.TickCount));
+                    }
+                });
+        }
+    }
+}

src/Windows/Avalonia.Win32/Interop/UnmanagedMethods.cs

@@ -26,6 +26,9 @@ namespace Avalonia.Win32.Interop
 
         public delegate void TimeCallback(uint uTimerID, uint uMsg, UIntPtr dwUser, UIntPtr dw1, UIntPtr dw2);
 
+        [UnmanagedFunctionPointer(CallingConvention.StdCall)]
+        public delegate void WaitOrTimerCallback(IntPtr lpParameter, bool timerOrWaitFired);
+
         public delegate IntPtr WndProc(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam);
 
         public enum Cursor
@@ -848,11 +851,25 @@ namespace Avalonia.Win32.Interop
         [DllImport("user32.dll")]
         public static extern bool ShowWindow(IntPtr hWnd, ShowWindowCommand nCmdShow);
 
-        [DllImport("Winmm.dll")]
+        [DllImport("kernel32.dll", SetLastError = true)]
-        public static extern uint timeKillEvent(uint uTimerID);
+        public static extern IntPtr CreateTimerQueue();
+
+        [DllImport("kernel32.dll", SetLastError = true)]
+        public static extern bool DeleteTimerQueueEx(IntPtr TimerQueue, IntPtr CompletionEvent);
+
+        [DllImport("kernel32.dll", SetLastError = true)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        public static extern bool CreateTimerQueueTimer(
+            out IntPtr phNewTimer,
+            IntPtr TimerQueue,
+            WaitOrTimerCallback Callback,
+            IntPtr Parameter,
+            uint DueTime,
+            uint Period,
+            uint Flags);
 
-        [DllImport("Winmm.dll")]
+        [DllImport("kernel32.dll", SetLastError = true)]
-        public static extern uint timeSetEvent(uint uDelay, uint uResolution, TimeCallback lpTimeProc, UIntPtr dwUser, uint fuEvent);
+        public static extern bool DeleteTimerQueueTimer(IntPtr TimerQueue, IntPtr Timer, IntPtr CompletionEvent);
 
         [DllImport("user32.dll")]
         public static extern int ToUnicode(

src/Windows/Avalonia.Win32/RenderLoop.cs

@@ -1,35 +0,0 @@
-using System;
-using System.Reactive.Disposables;
-using Avalonia.Rendering;
-using Avalonia.Win32.Interop;
-
-namespace Avalonia.Win32
-{
-    internal class RenderLoop : DefaultRenderLoop
-    {
-        private UnmanagedMethods.TimeCallback timerDelegate;
-
-        public RenderLoop(int framesPerSecond)
-            : base(framesPerSecond)
-        {
-        }
-
-        protected override IDisposable StartCore(Action tick)
-        {
-            timerDelegate = (id, uMsg, user, dw1, dw2) => tick();
-
-            var handle = UnmanagedMethods.timeSetEvent(
-                (uint)(1000 / FramesPerSecond),
-                0,
-                timerDelegate,
-                UIntPtr.Zero,
-                1);
-
-            return Disposable.Create(() =>
-            {
-                timerDelegate = null;
-                UnmanagedMethods.timeKillEvent(handle);
-            });
-        }
-    }
-}

src/Windows/Avalonia.Win32/RenderTimer.cs

@@ -0,0 +1,56 @@
+using System;
+using System.Reactive.Disposables;
+using System.Threading;
+using Avalonia.Rendering;
+using Avalonia.Win32.Interop;
+
+namespace Avalonia.Win32
+{
+    internal class RenderTimer : DefaultRenderTimer
+    {
+        private UnmanagedMethods.WaitOrTimerCallback timerDelegate;
+
+        private static IntPtr _timerQueue;
+
+        private static void EnsureTimerQueueCreated()
+        {
+            if (Volatile.Read(ref _timerQueue) == null)
+            {
+                var queue = UnmanagedMethods.CreateTimerQueue();
+                if (Interlocked.CompareExchange(ref _timerQueue, queue, IntPtr.Zero) != IntPtr.Zero)
+                {
+                    UnmanagedMethods.DeleteTimerQueueEx(queue, IntPtr.Zero);
+                }
+            }
+        }
+
+        public RenderTimer(int framesPerSecond)
+            : base(framesPerSecond)
+        {
+        }
+
+        protected override IDisposable StartCore(Action<TimeSpan> tick)
+        {
+            EnsureTimerQueueCreated();
+            var msPerFrame = 1000 / FramesPerSecond;
+
+            timerDelegate = (_, __) => tick(TimeSpan.FromMilliseconds(Environment.TickCount));
+
+            UnmanagedMethods.CreateTimerQueueTimer(
+                out var timer,
+                _timerQueue,
+                timerDelegate,
+                IntPtr.Zero,
+                (uint)msPerFrame,
+                (uint)msPerFrame,
+                0
+                );
+
+            return Disposable.Create(() =>
+            {
+                timerDelegate = null;
+                UnmanagedMethods.DeleteTimerQueueTimer(_timerQueue, timer, IntPtr.Zero);
+            });
+        }
+    }
+}

src/Windows/Avalonia.Win32/Win32Platform.cs

@@ -9,6 +9,7 @@ using System.IO;
 using System.Reactive.Disposables;
 using System.Runtime.InteropServices;
 using System.Threading;
+using Avalonia.Animation;
 using Avalonia.Controls;
 using Avalonia.Controls.Platform;
 using Avalonia.Input;
@@ -82,7 +83,8 @@ namespace Avalonia.Win32
                 .Bind<IKeyboardDevice>().ToConstant(WindowsKeyboardDevice.Instance)
                 .Bind<IPlatformSettings>().ToConstant(s_instance)
                 .Bind<IPlatformThreadingInterface>().ToConstant(s_instance)
-                .Bind<IRenderLoop>().ToConstant(new RenderLoop(60))
+                .Bind<IRenderLoop>().ToConstant(new RenderLoop())
+                .Bind<IRenderTimer>().ToConstant(new RenderTimer(60))
                 .Bind<ISystemDialogImpl>().ToSingleton<SystemDialogImpl>()
                 .Bind<IWindowingPlatform>().ToConstant(s_instance)
                 .Bind<IPlatformIconLoader>().ToConstant(s_instance);

src/iOS/Avalonia.iOS/DisplayLinkRenderLoop.cs → src/iOS/Avalonia.iOS/DisplayLinkRenderTimer.cs

@@ -5,11 +5,12 @@ using Foundation;
 
 namespace Avalonia.iOS
 {
-    class DisplayLinkRenderLoop : IRenderLoop
+    class DisplayLinkRenderTimer : IRenderTimer
     {
-        public event EventHandler<EventArgs> Tick;
+        public event Action<TimeSpan> Tick;
         private CADisplayLink _link;
-        public DisplayLinkRenderLoop()
+
+        public DisplayLinkRenderTimer()
         {
 
             _link = CADisplayLink.Create(OnFrame);
@@ -20,7 +21,7 @@ namespace Avalonia.iOS
         {
             try
             {
-                Tick?.Invoke(this, new EventArgs());
+                Tick?.Invoke(TimeSpan.FromMilliseconds(Environment.TickCount));
             }
             catch (Exception)
             {

src/iOS/Avalonia.iOS/iOSPlatform.cs

@@ -41,7 +41,8 @@ namespace Avalonia.iOS
                 .Bind<IPlatformThreadingInterface>().ToConstant(PlatformThreadingInterface.Instance)
                 .Bind<IPlatformIconLoader>().ToSingleton<PlatformIconLoader>()
                 .Bind<IWindowingPlatform>().ToSingleton<WindowingPlatformImpl>()
-                .Bind<IRenderLoop>().ToSingleton<DisplayLinkRenderLoop>();
+                .Bind<IRenderTimer>().ToSingleton<DisplayLinkRenderTimer>()
+                .Bind<IRenderLoop>().ToSingleton<RenderLoop>();
         }
     }
 }

tests/Avalonia.Base.UnitTests/AvaloniaObjectTests_Binding.cs

@@ -479,6 +479,18 @@ namespace Avalonia.Base.UnitTests
             Assert.False(source.SetterCalled);
         }
 
+        [Fact]
+        public void Disposing_Completed_Binding_Does_Not_Throw()
+        {
+            var target = new Class1();
+            var source = new Subject<string>();
+            var subscription = target.Bind(Class1.FooProperty, source);
+
+            source.OnCompleted();
+
+            subscription.Dispose();
+        }
+
         /// <summary>
         /// Returns an observable that returns a single value but does not complete.
         /// </summary>
@@ -595,4 +607,4 @@ namespace Avalonia.Base.UnitTests
             public bool SetterCalled { get; private set; }
         }
     }
-}
+}

tests/Avalonia.Controls.UnitTests/BorderTests.cs

@@ -1,6 +1,10 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
+using Avalonia.Media;
+using Avalonia.Rendering;
+using Avalonia.UnitTests;
+using Moq;
 using Xunit;
 
 namespace Avalonia.Controls.UnitTests
@@ -42,5 +46,22 @@ namespace Avalonia.Controls.UnitTests
 
             Assert.Equal(new Rect(6, 6, 0, 0), content.Bounds);
         }
+
+        [Fact]
+        public void Changing_Background_Brush_Color_Should_Invalidate_Visual()
+        {
+            var target = new Border()
+            {
+                Background = new SolidColorBrush(Colors.Red),
+            };
+
+            var root = new TestRoot(target);
+            var renderer = Mock.Get(root.Renderer);
+            renderer.ResetCalls();
+
+            ((SolidColorBrush)target.Background).Color = Colors.Green;
+
+            renderer.Verify(x => x.AddDirty(target), Times.Once);
+        }
     }
 }

tests/Avalonia.Controls.UnitTests/MenuItemTests.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Xunit;
+
+namespace Avalonia.Controls.UnitTests
+{
+    public class MenuItemTests
+    {
+        [Fact]
+        public void Header_Of_Minus_Should_Apply_Separator_Pseudoclass()
+        {
+            var target = new MenuItem { Header = "-" };
+
+            Assert.True(target.Classes.Contains(":separator"));
+        }
+
+        [Fact]
+        public void Separator_Item_Should_Set_Focusable_False()
+        {
+            var target = new MenuItem { Header = "-" };
+
+            Assert.False(target.Focusable);
+        }
+    }
+}

tests/Avalonia.Controls.UnitTests/PanelTests.cs

@@ -3,7 +3,11 @@
 
 using System.Linq;
 using Avalonia.LogicalTree;
+using Avalonia.Media;
+using Avalonia.Rendering;
+using Avalonia.UnitTests;
 using Avalonia.VisualTree;
+using Moq;
 using Xunit;
 
 namespace Avalonia.Controls.UnitTests
@@ -115,5 +119,22 @@ namespace Avalonia.Controls.UnitTests
             Assert.Equal(new[] { child2, child1 }, panel.GetLogicalChildren());
             Assert.Equal(new[] { child2, child1 }, panel.GetVisualChildren());
         }
+
+        [Fact]
+        public void Changing_Background_Brush_Color_Should_Invalidate_Visual()
+        {
+            var target = new Panel()
+            {
+                Background = new SolidColorBrush(Colors.Red),
+            };
+
+            var root = new TestRoot(target);
+            var renderer = Mock.Get(root.Renderer);
+            renderer.ResetCalls();
+
+            ((SolidColorBrush)target.Background).Color = Colors.Green;
+
+            renderer.Verify(x => x.AddDirty(target), Times.Once);
+        }
     }
 }

tests/Avalonia.Controls.UnitTests/Presenters/ContentPresenterTests_Standalone.cs

@@ -13,6 +13,7 @@ using System;
 using System.Linq;
 using Xunit;
 using Avalonia.Rendering;
+using Avalonia.Media;
 
 namespace Avalonia.Controls.UnitTests.Presenters
 {
@@ -203,5 +204,22 @@ namespace Avalonia.Controls.UnitTests.Presenters
             Assert.NotEqual(foo, logicalChildren.First());
         }
 
+
+        [Fact]
+        public void Changing_Background_Brush_Color_Should_Invalidate_Visual()
+        {
+            var target = new ContentPresenter()
+            {
+                Background = new SolidColorBrush(Colors.Red),
+            };
+
+            var root = new TestRoot(target);
+            var renderer = Mock.Get(root.Renderer);
+            renderer.ResetCalls();
+
+            ((SolidColorBrush)target.Background).Color = Colors.Green;
+
+            renderer.Verify(x => x.AddDirty(target), Times.Once);
+        }
     }
-}
+}