Merge branch 'master' into dont-build-core-tests

samples/Previewer/MainWindow.xaml.cs

@@ -39,7 +39,7 @@ namespace Previewer
             }));
             new BsonTcpTransport().Listen(IPAddress.Loopback, 25000, t =>
             {
-                Dispatcher.UIThread.InvokeAsync(() =>
+                Dispatcher.UIThread.Post(() =>
                 {
                     if (_connection != null)
                     {
@@ -61,7 +61,7 @@ namespace Previewer
 
         private void OnMessage(IAvaloniaRemoteTransportConnection transport, object obj)
         {
-            Dispatcher.UIThread.InvokeAsync(() =>
+            Dispatcher.UIThread.Post(() =>
             {
                 if (transport != _connection)
                     return;

samples/RemoteTest/Program.cs

@@ -25,7 +25,7 @@ namespace RemoteTest
             var transport = new BsonTcpTransport();
             transport.Listen(IPAddress.Loopback, port, sc =>
             {
-                Dispatcher.UIThread.InvokeAsync(() =>
+                Dispatcher.UIThread.Post(() =>
                 {
                     new RemoteServer(sc).Content = new MainView();
                 });
@@ -34,7 +34,7 @@ namespace RemoteTest
             var cts = new CancellationTokenSource();
             transport.Connect(IPAddress.Loopback, port).ContinueWith(t =>
             {
-                Dispatcher.UIThread.InvokeAsync(() =>
+                Dispatcher.UIThread.Post(() =>
                 {
                     var window = new Window()
                     {

samples/VirtualizationTest/MainWindow.xaml

@@ -21,6 +21,12 @@
             <TextBox Watermark="Viewport"
                      UseFloatingWatermark="True"
                      Text="{Binding #listBox.Scroll.Viewport, Mode=OneWay}"/>
+            <TextBlock>Horiz. ScrollBar</TextBlock>
+            <DropDown Items="{Binding ScrollBarVisibilities}"
+                      SelectedItem="{Binding HorizontalScrollBarVisibility}"/>
+            <TextBlock>Vert. ScrollBar</TextBlock>
+            <DropDown Items="{Binding ScrollBarVisibilities}"
+                      SelectedItem="{Binding VerticalScrollBarVisibility}"/>
             <TextBox Watermark="Item to Create"
                      UseFloatingWatermark="True"
                      Text="{Binding NewItemString}"/>
@@ -35,7 +41,9 @@
                  Items="{Binding Items}" 
                  SelectedItems="{Binding SelectedItems}"
                  SelectionMode="Multiple"
-                 VirtualizationMode="{Binding VirtualizationMode}">
+                 VirtualizationMode="{Binding VirtualizationMode}"
+                 ScrollViewer.HorizontalScrollBarVisibility="{Binding HorizontalScrollBarVisibility, Mode=TwoWay}"
+                 ScrollViewer.VerticalScrollBarVisibility="{Binding VerticalScrollBarVisibility, Mode=TwoWay}">
             <ListBox.ItemsPanel>
                 <ItemsPanelTemplate>
                     <VirtualizingStackPanel Orientation="{Binding Orientation}"/>
@@ -43,7 +51,7 @@
             </ListBox.ItemsPanel>
             <ListBox.ItemTemplate>
                 <DataTemplate>
-                    <TextBlock Text="{Binding Header}"/>
+                    <TextBlock Text="{Binding Header}" TextWrapping="Wrap"/>
                 </DataTemplate>
             </ListBox.ItemTemplate>
         </ListBox>

samples/VirtualizationTest/ViewModels/MainWindowViewModel.cs

@@ -6,6 +6,7 @@ using System.Collections.Generic;
 using System.Linq;
 using Avalonia.Collections;
 using Avalonia.Controls;
+using Avalonia.Controls.Primitives;
 using ReactiveUI;
 
 namespace VirtualizationTest.ViewModels
@@ -17,6 +18,8 @@ namespace VirtualizationTest.ViewModels
         private int _newItemIndex;
         private IReactiveList<ItemViewModel> _items;
         private string _prefix = "Item";
+        private ScrollBarVisibility _horizontalScrollBarVisibility = ScrollBarVisibility.Auto;
+        private ScrollBarVisibility _verticalScrollBarVisibility = ScrollBarVisibility.Auto;
         private Orientation _orientation = Orientation.Vertical;
         private ItemVirtualizationMode _virtualizationMode = ItemVirtualizationMode.Simple;
 
@@ -64,6 +67,21 @@ namespace VirtualizationTest.ViewModels
         public IEnumerable<Orientation> Orientations =>
             Enum.GetValues(typeof(Orientation)).Cast<Orientation>();
 
+        public ScrollBarVisibility HorizontalScrollBarVisibility
+        {
+            get { return _horizontalScrollBarVisibility; }
+            set { this.RaiseAndSetIfChanged(ref _horizontalScrollBarVisibility, value); }
+        }
+
+        public ScrollBarVisibility VerticalScrollBarVisibility
+        {
+            get { return _verticalScrollBarVisibility; }
+            set { this.RaiseAndSetIfChanged(ref _verticalScrollBarVisibility, value); }
+        }
+
+        public IEnumerable<ScrollBarVisibility> ScrollBarVisibilities =>
+            Enum.GetValues(typeof(ScrollBarVisibility)).Cast<ScrollBarVisibility>();
+
         public ItemVirtualizationMode VirtualizationMode
         {
             get { return _virtualizationMode; }

src/Avalonia.Base/AvaloniaObject.cs

@@ -774,7 +774,7 @@ namespace Avalonia
             }
             else
             {
-                Dispatcher.UIThread.InvokeAsync(Set);
+                Dispatcher.UIThread.Post(Set);
             }
         }
 

src/Avalonia.Base/PriorityBindingEntry.cs

@@ -123,7 +123,7 @@ namespace Avalonia
             }
             else
             {
-                Dispatcher.UIThread.InvokeAsync(Signal);
+                Dispatcher.UIThread.Post(Signal);
             }
         }
 
@@ -135,7 +135,7 @@ namespace Avalonia
             }
             else
             {
-                Dispatcher.UIThread.InvokeAsync(() => _owner.Completed(this));
+                Dispatcher.UIThread.Post(() => _owner.Completed(this));
             }
         }
     }

src/Avalonia.Base/Threading/AvaloniaScheduler.cs

@@ -33,7 +33,7 @@ namespace Avalonia.Threading
                 if (!Dispatcher.UIThread.CheckAccess())
                 {
                     var cancellation = new CancellationDisposable();
-                    Dispatcher.UIThread.InvokeAsync(() =>
+                    Dispatcher.UIThread.Post(() =>
                     {
                         if (!cancellation.Token.IsCancellationRequested)
                         {

src/Avalonia.Base/Threading/AvaloniaSynchronizationContext.cs

@@ -36,7 +36,7 @@ namespace Avalonia.Threading
         /// <inheritdoc/>
         public override void Post(SendOrPostCallback d, object state)
         {
-           Dispatcher.UIThread.InvokeAsync(() => d(state), DispatcherPriority.Send);
+           Dispatcher.UIThread.Post(() => d(state), DispatcherPriority.Send);
         }
 
         /// <inheritdoc/>
@@ -45,7 +45,7 @@ namespace Avalonia.Threading
             if (Dispatcher.UIThread.CheckAccess())
                 d(state);
             else
-                Dispatcher.UIThread.InvokeTaskAsync(() => d(state), DispatcherPriority.Send).Wait();
+                Dispatcher.UIThread.InvokeAsync(() => d(state), DispatcherPriority.Send).Wait();
         }
     }
 }

src/Avalonia.Base/Threading/Dispatcher.cs

@@ -79,13 +79,13 @@ namespace Avalonia.Threading
         public void RunJobs(DispatcherPriority minimumPriority) => _jobRunner.RunJobs(minimumPriority);
 
         /// <inheritdoc/>
-        public Task InvokeTaskAsync(Action action, DispatcherPriority priority = DispatcherPriority.Normal)
+        public Task InvokeAsync(Action action, DispatcherPriority priority = DispatcherPriority.Normal)
         {
             return _jobRunner?.InvokeAsync(action, priority);
         }
 
         /// <inheritdoc/>
-        public void InvokeAsync(Action action, DispatcherPriority priority = DispatcherPriority.Normal)
+        public void Post(Action action, DispatcherPriority priority = DispatcherPriority.Normal)
         {
             _jobRunner?.Post(action, priority);
         }

src/Avalonia.Base/Threading/IDispatcher.cs

@@ -25,7 +25,7 @@ namespace Avalonia.Threading
         /// <param name="action">The method.</param>
         /// <param name="priority">The priority with which to invoke the method.</param>
         /// <returns>A task that can be used to track the method's execution.</returns>
-        void InvokeAsync(Action action, DispatcherPriority priority = DispatcherPriority.Normal);
+        void Post(Action action, DispatcherPriority priority = DispatcherPriority.Normal);
 
         /// <summary>
         /// Post action that will be invoked on main thread
@@ -34,6 +34,6 @@ namespace Avalonia.Threading
         /// <param name="priority">The priority with which to invoke the method.</param>
         // TODO: The naming of this method is confusing: the Async suffix usually means return a task.
         // Remove this and rename InvokeTaskAsync as InvokeAsync. See #816.
-        Task InvokeTaskAsync(Action action, DispatcherPriority priority = DispatcherPriority.Normal);
+        Task InvokeAsync(Action action, DispatcherPriority priority = DispatcherPriority.Normal);
     }
 }

src/Avalonia.Controls/Presenters/ItemVirtualizerSimple.cs

@@ -5,6 +5,7 @@ using System;
 using System.Collections;
 using System.Collections.Specialized;
 using System.Linq;
+using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Utils;
 using Avalonia.Input;
 using Avalonia.Layout;
@@ -97,6 +98,7 @@ namespace Avalonia.Controls.Presenters
         /// <inheritdoc/>
         public override Size MeasureOverride(Size availableSize)
         {
+            var scrollable = (ILogicalScrollable)Owner;
             var visualRoot = Owner.GetVisualRoot();
             var maxAvailableSize = (visualRoot as WindowBase)?.PlatformImpl?.MaxClientSize
                  ?? (visualRoot as TopLevel)?.ClientSize;
@@ -115,7 +117,10 @@ namespace Avalonia.Controls.Presenters
                     }
                 }
 
-                availableSize = availableSize.WithWidth(double.PositiveInfinity);
+                if (scrollable.CanHorizontallyScroll)
+                {
+                    availableSize = availableSize.WithWidth(double.PositiveInfinity);
+                }
             }
             else
             {
@@ -127,7 +132,10 @@ namespace Avalonia.Controls.Presenters
                     }
                 }
 
-                availableSize = availableSize.WithHeight(double.PositiveInfinity);
+                if (scrollable.CanVerticallyScroll)
+                {
+                    availableSize = availableSize.WithHeight(double.PositiveInfinity);
+                }
             }
 
             Owner.Panel.Measure(availableSize);

src/Avalonia.Controls/Presenters/ItemsPresenter.cs

@@ -23,6 +23,8 @@ namespace Avalonia.Controls.Presenters
                 defaultValue: ItemVirtualizationMode.None);
 
         private ItemVirtualizer _virtualizer;
+        private bool _canHorizontallyScroll;
+        private bool _canVerticallyScroll;
 
         /// <summary>
         /// Initializes static members of the <see cref="ItemsPresenter"/> class.
@@ -46,6 +48,31 @@ namespace Avalonia.Controls.Presenters
             set { SetValue(VirtualizationModeProperty, value); }
         }
 
+        /// <summary>
+        /// Gets or sets a value indicating whether the content can be scrolled horizontally.
+        /// </summary>
+        bool ILogicalScrollable.CanHorizontallyScroll
+        {
+            get { return _canHorizontallyScroll; }
+            set
+            {
+                _canHorizontallyScroll = value;
+                InvalidateMeasure();
+            }
+        }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether the content can be scrolled horizontally.
+        /// </summary>
+        bool ILogicalScrollable.CanVerticallyScroll
+        {
+            get { return _canVerticallyScroll; }
+            set
+            {
+                _canVerticallyScroll = value;
+                InvalidateMeasure();
+            }
+        }
         /// <inheritdoc/>
         bool ILogicalScrollable.IsLogicalScrollEnabled
         {

src/Avalonia.Controls/Presenters/ScrollContentPresenter.cs

@@ -17,6 +17,24 @@ namespace Avalonia.Controls.Presenters
     /// </summary>
     public class ScrollContentPresenter : ContentPresenter, IPresenter, IScrollable
     {
+        /// <summary>
+        /// Defines the <see cref="CanHorizontallyScroll"/> property.
+        /// </summary>
+        public static readonly DirectProperty<ScrollContentPresenter, bool> CanHorizontallyScrollProperty =
+            AvaloniaProperty.RegisterDirect<ScrollContentPresenter, bool>(
+                nameof(CanHorizontallyScroll),
+                o => o.CanHorizontallyScroll,
+                (o, v) => o.CanHorizontallyScroll = v);
+
+        /// <summary>
+        /// Defines the <see cref="CanVerticallyScroll"/> property.
+        /// </summary>
+        public static readonly DirectProperty<ScrollContentPresenter, bool> CanVerticallyScrollProperty =
+            AvaloniaProperty.RegisterDirect<ScrollContentPresenter, bool>(
+                nameof(CanVerticallyScroll),
+                o => o.CanVerticallyScroll,
+                (o, v) => o.CanVerticallyScroll = v);
+
         /// <summary>
         /// Defines the <see cref="Extent"/> property.
         /// </summary>
@@ -41,12 +59,8 @@ namespace Avalonia.Controls.Presenters
                 o => o.Viewport,
                 (o, v) => o.Viewport = v);
 
-        /// <summary>
-        /// Defines the <see cref="CanScrollHorizontally"/> property.
-        /// </summary>
-        public static readonly StyledProperty<bool> CanScrollHorizontallyProperty =
-            ScrollViewer.CanScrollHorizontallyProperty.AddOwner<ScrollContentPresenter>();
-
+        private bool _canHorizontallyScroll;
+        private bool _canVerticallyScroll;
         private Size _extent;
         private Size _measuredExtent;
         private Vector _offset;
@@ -73,6 +87,24 @@ namespace Avalonia.Controls.Presenters
             this.GetObservable(ChildProperty).Subscribe(UpdateScrollableSubscription);
         }
 
+        /// <summary>
+        /// Gets or sets a value indicating whether the content can be scrolled horizontally.
+        /// </summary>
+        public bool CanHorizontallyScroll
+        {
+            get { return _canHorizontallyScroll; }
+            set { SetAndRaise(CanHorizontallyScrollProperty, ref _canHorizontallyScroll, value); }
+        }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether the content can be scrolled horizontally.
+        /// </summary>
+        public bool CanVerticallyScroll
+        {
+            get { return _canVerticallyScroll; }
+            set { SetAndRaise(CanVerticallyScrollProperty, ref _canVerticallyScroll, value); }
+        }
+
         /// <summary>
         /// Gets the extent of the scrollable content.
         /// </summary>
@@ -100,11 +132,6 @@ namespace Avalonia.Controls.Presenters
             private set { SetAndRaise(ViewportProperty, ref _viewport, value); }
         }
 
-        /// <summary>
-        /// Gets a value indicating whether the content can be scrolled horizontally.
-        /// </summary>
-        public bool CanScrollHorizontally => GetValue(CanScrollHorizontallyProperty);
-
         /// <summary>
         /// Attempts to bring a portion of the target visual into view by scrolling the content.
         /// </summary>
@@ -182,10 +209,15 @@ namespace Avalonia.Controls.Presenters
                 {
                     measureSize = new Size(double.PositiveInfinity, double.PositiveInfinity);
 
-                    if (!CanScrollHorizontally)
+                    if (!CanHorizontallyScroll)
                     {
                         measureSize = measureSize.WithWidth(availableSize.Width);
                     }
+
+                    if (!CanVerticallyScroll)
+                    {
+                        measureSize = measureSize.WithHeight(availableSize.Height);
+                    }
                 }
 
                 child.Measure(measureSize);
@@ -289,7 +321,12 @@ namespace Avalonia.Controls.Presenters
                 if (scrollable.IsLogicalScrollEnabled == true)
                 {
                     _logicalScrollSubscription = new CompositeDisposable(
-                        this.GetObservable(OffsetProperty).Skip(1).Subscribe(x => scrollable.Offset = x),
+                        this.GetObservable(CanHorizontallyScrollProperty)
+                            .Subscribe(x => scrollable.CanHorizontallyScroll = x),
+                        this.GetObservable(CanVerticallyScrollProperty)
+                            .Subscribe(x => scrollable.CanVerticallyScroll = x),
+                        this.GetObservable(OffsetProperty)
+                            .Skip(1).Subscribe(x => scrollable.Offset = x),
                         Disposable.Create(() => scrollable.InvalidateScroll = null));
                     UpdateFromScrollable(scrollable);
                 }

src/Avalonia.Controls/Presenters/TextPresenter.cs

@@ -191,7 +191,7 @@ namespace Avalonia.Controls.Presenters
                     // The measure is currently invalid so there's no point trying to bring the 
                     // current char into view until a measure has been carried out as the scroll
                     // viewer extents may not be up-to-date.
-                    Dispatcher.UIThread.InvokeAsync(
+                    Dispatcher.UIThread.Post(
                         () =>
                         {
                             var rect = FormattedText.HitTestTextPosition(caretIndex);

src/Avalonia.Controls/Primitives/AdornerLayer.cs

@@ -18,8 +18,6 @@ namespace Avalonia.Controls.Primitives
         private static readonly AttachedProperty<AdornedElementInfo> s_adornedElementInfoProperty =
             AvaloniaProperty.RegisterAttached<AdornerLayer, Visual, AdornedElementInfo>("AdornedElementInfo");
 
-        private readonly BoundsTracker _tracker = new BoundsTracker();
-
         static AdornerLayer()
         {
             AdornedElementProperty.Changed.Subscribe(AdornedElementChanged);
@@ -118,7 +116,7 @@ namespace Avalonia.Controls.Primitives
                     adorner.SetValue(s_adornedElementInfoProperty, info);
                 }
 
-                info.Subscription = _tracker.Track(adorned).Subscribe(x =>
+                info.Subscription = adorned.GetObservable(TransformedBoundsProperty).Subscribe(x =>
                 {
                     info.Bounds = x;
                     InvalidateArrange();

src/Avalonia.Controls/Primitives/ILogicalScrollable.cs

@@ -19,6 +19,16 @@ namespace Avalonia.Controls.Primitives
     /// </remarks>
     public interface ILogicalScrollable : IScrollable
     {
+        /// <summary>
+        /// Gets or sets a value indicating whether the content can be scrolled horizontally.
+        /// </summary>
+        bool CanHorizontallyScroll { get; set; }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether the content can be scrolled horizontally.
+        /// </summary>
+        bool CanVerticallyScroll { get; set; }
+
         /// <summary>
         /// Gets a value indicating whether logical scrolling is enabled on the control.
         /// </summary>

src/Avalonia.Controls/Primitives/ScrollBar.cs

@@ -99,6 +99,7 @@ namespace Avalonia.Controls.Primitives
                 case ScrollBarVisibility.Visible:
                     return true;
 
+                case ScrollBarVisibility.Disabled:
                 case ScrollBarVisibility.Hidden:
                     return false;
 

src/Avalonia.Controls/Primitives/ScrollBarVisibility.cs

@@ -5,8 +5,9 @@ namespace Avalonia.Controls.Primitives
 {
     public enum ScrollBarVisibility
     {
+        Disabled,
         Auto,
-        Visible,
         Hidden,
+        Visible,
     }
 }

src/Avalonia.Controls/Remote/RemoteWidget.cs

@@ -18,7 +18,7 @@ namespace Avalonia.Controls.Remote
         public RemoteWidget(IAvaloniaRemoteTransportConnection connection)
         {
             _connection = connection;
-            _connection.OnMessage += (t, msg) => Dispatcher.UIThread.InvokeAsync(() => OnMessage(msg));
+            _connection.OnMessage += (t, msg) => Dispatcher.UIThread.Post(() => OnMessage(msg));
             _connection.Send(new ClientSupportedPixelFormatsMessage
             {
                 Formats = new[]

src/Avalonia.Controls/Remote/Server/RemoteServerTopLevelImpl.cs

@@ -46,16 +46,16 @@ namespace Avalonia.Controls.Remote.Server
                     {
                         _lastReceivedFrame = lastFrame.SequenceId;
                     }
-                    Dispatcher.UIThread.InvokeAsync(RenderIfNeeded);
+                    Dispatcher.UIThread.Post(RenderIfNeeded);
                 }
                 if (obj is ClientSupportedPixelFormatsMessage supportedFormats)
                 {
                     lock (_lock)
                         _supportedFormats = supportedFormats.Formats;
-                    Dispatcher.UIThread.InvokeAsync(RenderIfNeeded);
+                    Dispatcher.UIThread.Post(RenderIfNeeded);
                 }
                 if (obj is MeasureViewportMessage measure)
-                    Dispatcher.UIThread.InvokeAsync(() =>
+                    Dispatcher.UIThread.Post(() =>
                     {
                         var m = Measure(new Size(measure.Width, measure.Height));
                         _transport.Send(new MeasureViewportMessage
@@ -69,7 +69,7 @@ namespace Avalonia.Controls.Remote.Server
                     lock (_lock)
                     {
                         if (_pendingAllocation == null)
-                            Dispatcher.UIThread.InvokeAsync(() =>
+                            Dispatcher.UIThread.Post(() =>
                             {
                                 ClientViewportAllocatedMessage allocation;
                                 lock (_lock)
@@ -168,7 +168,7 @@ namespace Avalonia.Controls.Remote.Server
         public override void Invalidate(Rect rect)
         {
             _invalidated = true;
-            Dispatcher.UIThread.InvokeAsync(RenderIfNeeded);
+            Dispatcher.UIThread.Post(RenderIfNeeded);
         }
 
         public override IMouseDevice MouseDevice { get; } = new MouseDevice();

src/Avalonia.Controls/ScrollViewer.cs

@@ -2,8 +2,6 @@
 // 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.Controls.Presenters;
 using Avalonia.Controls.Primitives;
 
@@ -15,16 +13,34 @@ namespace Avalonia.Controls
     public class ScrollViewer : ContentControl, IScrollable
     {
         /// <summary>
-        /// Defines the <see cref="CanScrollHorizontally"/> property.
+        /// Defines the <see cref="CanHorizontallyScroll"/> property.
         /// </summary>
-        public static readonly StyledProperty<bool> CanScrollHorizontallyProperty =
-            AvaloniaProperty.Register<ScrollViewer, bool>(nameof(CanScrollHorizontally), true);
+        /// <remarks>
+        /// There is no public C# accessor for this property as it is intended to be bound to by a 
+        /// <see cref="ScrollContentPresenter"/> in the control's template.
+        /// </remarks>
+        public static readonly DirectProperty<ScrollViewer, bool> CanHorizontallyScrollProperty =
+            AvaloniaProperty.RegisterDirect<ScrollViewer, bool>(
+                nameof(CanHorizontallyScroll),
+                o => o.CanHorizontallyScroll);
+
+        /// <summary>
+        /// Defines the <see cref="CanVerticallyScroll"/> property.
+        /// </summary>
+        /// <remarks>
+        /// There is no public C# accessor for this property as it is intended to be bound to by a 
+        /// <see cref="ScrollContentPresenter"/> in the control's template.
+        /// </remarks>
+        public static readonly DirectProperty<ScrollViewer, bool> CanVerticallyScrollProperty =
+            AvaloniaProperty.RegisterDirect<ScrollViewer, bool>(
+                nameof(CanVerticallyScroll),
+                o => o.CanVerticallyScroll);
 
         /// <summary>
         /// Defines the <see cref="Extent"/> property.
         /// </summary>
         public static readonly DirectProperty<ScrollViewer, Size> ExtentProperty =
-            AvaloniaProperty.RegisterDirect<ScrollViewer, Size>(nameof(Extent), 
+            AvaloniaProperty.RegisterDirect<ScrollViewer, Size>(nameof(Extent),
                 o => o.Extent,
                 (o, v) => o.Extent = v);
 
@@ -41,7 +57,7 @@ namespace Avalonia.Controls
         /// Defines the <see cref="Viewport"/> property.
         /// </summary>
         public static readonly DirectProperty<ScrollViewer, Size> ViewportProperty =
-            AvaloniaProperty.RegisterDirect<ScrollViewer, Size>(nameof(Viewport), 
+            AvaloniaProperty.RegisterDirect<ScrollViewer, Size>(nameof(Viewport),
                 o => o.Viewport,
                 (o, v) => o.Viewport = v);
 
@@ -85,14 +101,10 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="HorizontalScrollBarVisibility"/> property.
         /// </summary>
-        /// <remarks>
-        /// There is no public C# accessor for this property as it is intended to be bound to by a 
-        /// <see cref="ScrollContentPresenter"/> in the control's template.
-        /// </remarks>
         public static readonly AttachedProperty<ScrollBarVisibility> HorizontalScrollBarVisibilityProperty =
             AvaloniaProperty.RegisterAttached<ScrollViewer, Control, ScrollBarVisibility>(
                 nameof(HorizontalScrollBarVisibility),
-                ScrollBarVisibility.Auto);
+                ScrollBarVisibility.Hidden);
 
         /// <summary>
         /// Defines the VerticalScrollBarMaximum property.
@@ -136,7 +148,7 @@ namespace Avalonia.Controls
         /// </summary>
         public static readonly AttachedProperty<ScrollBarVisibility> VerticalScrollBarVisibilityProperty =
             AvaloniaProperty.RegisterAttached<ScrollViewer, Control, ScrollBarVisibility>(
-                nameof(VerticalScrollBarVisibility), 
+                nameof(VerticalScrollBarVisibility),
                 ScrollBarVisibility.Auto);
 
         private Size _extent;
@@ -150,6 +162,8 @@ namespace Avalonia.Controls
         {
             AffectsValidation(ExtentProperty, OffsetProperty);
             AffectsValidation(ViewportProperty, OffsetProperty);
+            HorizontalScrollBarVisibilityProperty.Changed.AddClassHandler<ScrollViewer>(x => x.ScrollBarVisibilityChanged);
+            VerticalScrollBarVisibilityProperty.Changed.AddClassHandler<ScrollViewer>(x => x.ScrollBarVisibilityChanged);
         }
 
         /// <summary>
@@ -218,15 +232,6 @@ namespace Avalonia.Controls
             }
         }
 
-        /// <summary>
-        /// Gets a value indicating whether the content can be scrolled horizontally.
-        /// </summary>
-        public bool CanScrollHorizontally
-        {
-            get { return GetValue(CanScrollHorizontallyProperty); }
-            set { SetValue(CanScrollHorizontallyProperty, value); }
-        }
-
         /// <summary>
         /// Gets or sets the horizontal scrollbar visibility.
         /// </summary>
@@ -245,6 +250,22 @@ namespace Avalonia.Controls
             set { SetValue(VerticalScrollBarVisibilityProperty, value); }
         }
 
+        /// <summary>
+        /// Gets a value indicating whether the viewer can scroll horizontally.
+        /// </summary>
+        protected bool CanHorizontallyScroll
+        {
+            get { return HorizontalScrollBarVisibility != ScrollBarVisibility.Disabled; }
+        }
+
+        /// <summary>
+        /// Gets a value indicating whether the viewer can scroll vertically.
+        /// </summary>
+        protected bool CanVerticallyScroll
+        {
+            get { return VerticalScrollBarVisibility != ScrollBarVisibility.Disabled; }
+        }
+
         /// <summary>
         /// Gets the maximum horizontal scrollbar value.
         /// </summary>
@@ -316,7 +337,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="control">The control to read the value from.</param>
         /// <returns>The value of the property.</returns>
-        public ScrollBarVisibility GetHorizontalScrollBarVisibility(Control control)
+        public static ScrollBarVisibility GetHorizontalScrollBarVisibility(Control control)
         {
             return control.GetValue(HorizontalScrollBarVisibilityProperty);
         }
@@ -326,7 +347,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="control">The control to set the value on.</param>
         /// <param name="value">The value of the property.</param>
-        public void SetHorizontalScrollBarVisibility(Control control, ScrollBarVisibility value)
+        public static void SetHorizontalScrollBarVisibility(Control control, ScrollBarVisibility value)
         {
             control.SetValue(HorizontalScrollBarVisibilityProperty, value);
         }
@@ -336,7 +357,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="control">The control to read the value from.</param>
         /// <returns>The value of the property.</returns>
-        public ScrollBarVisibility GetVerticalScrollBarVisibility(Control control)
+        public static ScrollBarVisibility GetVerticalScrollBarVisibility(Control control)
         {
             return control.GetValue(VerticalScrollBarVisibilityProperty);
         }
@@ -346,7 +367,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="control">The control to set the value on.</param>
         /// <param name="value">The value of the property.</param>
-        public void SetVerticalScrollBarVisibility(Control control, ScrollBarVisibility value)
+        public static void SetVerticalScrollBarVisibility(Control control, ScrollBarVisibility value)
         {
             control.SetValue(VerticalScrollBarVisibilityProperty, value);
         }
@@ -385,6 +406,30 @@ namespace Avalonia.Controls
             }
         }
 
+        private void ScrollBarVisibilityChanged(AvaloniaPropertyChangedEventArgs e)
+        {
+            var wasEnabled = !ScrollBarVisibility.Disabled.Equals(e.OldValue);
+            var isEnabled = !ScrollBarVisibility.Disabled.Equals(e.NewValue);
+
+            if (wasEnabled != isEnabled)
+            {
+                if (e.Property == HorizontalScrollBarVisibilityProperty)
+                {
+                    RaisePropertyChanged(
+                        CanHorizontallyScrollProperty,
+                        wasEnabled,
+                        isEnabled);
+                }
+                else if (e.Property == VerticalScrollBarVisibilityProperty)
+                {
+                    RaisePropertyChanged(
+                        CanVerticallyScrollProperty,
+                        wasEnabled,
+                        isEnabled);
+                }
+            }
+        }
+
         private void CalculatedPropertiesChanged()
         {
             // Pass old values of 0 here because we don't have the old values at this point,

src/Avalonia.Controls/TextBox.cs

@@ -8,7 +8,6 @@ using System.Linq;
 using System.Reactive.Linq;
 using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Primitives;
-using Avalonia.Controls.Templates;
 using Avalonia.Controls.Utils;
 using Avalonia.Input;
 using Avalonia.Interactivity;
@@ -26,9 +25,6 @@ namespace Avalonia.Controls
         public static readonly StyledProperty<bool> AcceptsTabProperty =
             AvaloniaProperty.Register<TextBox, bool>(nameof(AcceptsTab));
 
-        public static readonly DirectProperty<TextBox, bool> CanScrollHorizontallyProperty =
-            AvaloniaProperty.RegisterDirect<TextBox, bool>(nameof(CanScrollHorizontally), o => o.CanScrollHorizontally);
-
         public static readonly DirectProperty<TextBox, int> CaretIndexProperty =
             AvaloniaProperty.RegisterDirect<TextBox, int>(
                 nameof(CaretIndex),
@@ -92,7 +88,6 @@ namespace Avalonia.Controls
         private int _caretIndex;
         private int _selectionStart;
         private int _selectionEnd;
-        private bool _canScrollHorizontally;
         private TextPresenter _presenter;
         private UndoRedoHelper<UndoRedoState> _undoRedoHelper;
         private bool _ignoreTextChanges;
@@ -106,12 +101,11 @@ namespace Avalonia.Controls
 
         public TextBox()
         {
-            this.GetObservable(TextWrappingProperty)
-                .Select(x => x == TextWrapping.NoWrap)
-                .Subscribe(x => CanScrollHorizontally = x);
-
-            var horizontalScrollBarVisibility = this.GetObservable(AcceptsReturnProperty)
-                .Select(x => x ? ScrollBarVisibility.Auto : ScrollBarVisibility.Hidden);
+            var horizontalScrollBarVisibility = Observable.CombineLatest(
+                this.GetObservable(AcceptsReturnProperty),
+                this.GetObservable(TextWrappingProperty),
+                (acceptsReturn, wrapping) => acceptsReturn && wrapping == TextWrapping.NoWrap ?
+                    ScrollBarVisibility.Auto : ScrollBarVisibility.Disabled);
 
             Bind(
                 ScrollViewer.HorizontalScrollBarVisibilityProperty,
@@ -132,12 +126,6 @@ namespace Avalonia.Controls
             set { SetValue(AcceptsTabProperty, value); }
         }
 
-        public bool CanScrollHorizontally
-        {
-            get { return _canScrollHorizontally; }
-            private set { SetAndRaise(CanScrollHorizontallyProperty, ref _canScrollHorizontally, value); }
-        }
-
         public int CaretIndex
         {
             get

src/Avalonia.Controls/TreeView.cs

@@ -250,7 +250,7 @@ namespace Avalonia.Controls
 
                         if (AutoScrollToSelectedItem)
                         {
-                            Dispatcher.UIThread.InvokeAsync(container.ContainerControl.BringIntoView);
+                            Dispatcher.UIThread.Post(container.ContainerControl.BringIntoView);
                         }
 
                         break;

src/Avalonia.Controls/VirtualizingStackPanel.cs

@@ -3,11 +3,9 @@
 
 using System;
 using System.Collections.Specialized;
-using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Primitives;
 using Avalonia.Input;
 using Avalonia.Layout;
-using Avalonia.VisualTree;
 
 namespace Avalonia.Controls
 {

src/Avalonia.DesignerSupport/Remote/PreviewerWindowImpl.cs

@@ -49,7 +49,7 @@ namespace Avalonia.DesignerSupport.Remote
             // In previewer mode we completely ignore client-side viewport size
             if (obj is ClientViewportAllocatedMessage alloc)
             {
-                Dispatcher.UIThread.InvokeAsync(() => SetDpi(new Vector(alloc.DpiX, alloc.DpiY)));
+                Dispatcher.UIThread.Post(() => SetDpi(new Vector(alloc.DpiX, alloc.DpiY)));
                 return;
             }
             base.OnMessage(transport, obj);

src/Avalonia.DesignerSupport/Remote/RemoteDesignerEntryPoint.cs

@@ -140,7 +140,7 @@ namespace Avalonia.DesignerSupport.Remote
             };
         }
         
-        private static void OnTransportMessage(IAvaloniaRemoteTransportConnection transport, object obj) => Dispatcher.UIThread.InvokeAsync(() =>
+        private static void OnTransportMessage(IAvaloniaRemoteTransportConnection transport, object obj) => Dispatcher.UIThread.Post(() =>
         {
             if (obj is ClientSupportedPixelFormatsMessage formats)
             {

src/Avalonia.Layout/LayoutManager.cs

@@ -203,7 +203,7 @@ namespace Avalonia.Layout
         {
             if (!_queued && !_running)
             {
-                Dispatcher.UIThread.InvokeAsync(ExecuteLayoutPass, DispatcherPriority.Layout);
+                Dispatcher.UIThread.Post(ExecuteLayoutPass, DispatcherPriority.Layout);
                 _queued = true;
             }
         }

src/Avalonia.Themes.Default/ListBox.xaml

@@ -3,11 +3,16 @@
   <Setter Property="BorderBrush" Value="{DynamicResource ThemeBorderMidBrush}"/>
   <Setter Property="BorderThickness" Value="{DynamicResource ThemeBorderThickness}"/>
   <Setter Property="Padding" Value="4"/>
+  <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Auto"/>
+  <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
   <Setter Property="Template">
     <ControlTemplate>
       <Border BorderBrush="{TemplateBinding BorderBrush}"
               BorderThickness="{TemplateBinding BorderThickness}">
-        <ScrollViewer Name="PART_ScrollViewer" Background="{TemplateBinding Background}">
+        <ScrollViewer Name="PART_ScrollViewer"
+                      Background="{TemplateBinding Background}"
+                      HorizontalScrollBarVisibility="{TemplateBinding (ScrollViewer.HorizontalScrollBarVisibility)}"
+                      VerticalScrollBarVisibility="{TemplateBinding (ScrollViewer.VerticalScrollBarVisibility)}">
           <ItemsPresenter Name="PART_ItemsPresenter"
                           Items="{TemplateBinding Items}"
                           ItemsPanel="{TemplateBinding ItemsPanel}"

src/Avalonia.Themes.Default/ScrollViewer.xaml

@@ -6,12 +6,13 @@
       <Grid ColumnDefinitions="*,Auto" RowDefinitions="*,Auto">
         <ScrollContentPresenter Name="PART_ContentPresenter"
                                 Background="{TemplateBinding Background}"
+                                CanHorizontallyScroll="{TemplateBinding CanHorizontallyScroll}"
+                                CanVerticallyScroll="{TemplateBinding CanVerticallyScroll}"
                                 Content="{TemplateBinding Content}"
                                 Extent="{TemplateBinding Path=Extent, Mode=TwoWay}"
                                 Margin="{TemplateBinding Padding}"
                                 Offset="{TemplateBinding Path=Offset, Mode=TwoWay}"
-                                Viewport="{TemplateBinding Path=Viewport, Mode=TwoWay}"
-                                CanScrollHorizontally="{TemplateBinding CanScrollHorizontally}"/>
+                                Viewport="{TemplateBinding Path=Viewport, Mode=TwoWay}"/>
         <ScrollBar Name="horizontalScrollBar"
                    Orientation="Horizontal"
                    Maximum="{TemplateBinding HorizontalScrollBarMaximum}"

src/Avalonia.Themes.Default/TextBox.xaml

@@ -36,8 +36,7 @@
                 <Path Data="M14,7 A7,7 0 0,0 0,7 M0,7 A7,7 0 1,0 14,7 M7,3l0,5 M7,9l0,2" Stroke="{DynamicResource ErrorBrush}" StrokeThickness="2"/>
               </Canvas>
               
-              <ScrollViewer CanScrollHorizontally="{TemplateBinding CanScrollHorizontally}"
-                            HorizontalScrollBarVisibility="{TemplateBinding (ScrollViewer.HorizontalScrollBarVisibility)}"
+              <ScrollViewer HorizontalScrollBarVisibility="{TemplateBinding (ScrollViewer.HorizontalScrollBarVisibility)}"
                             VerticalScrollBarVisibility="{TemplateBinding (ScrollViewer.VerticalScrollBarVisibility)}">
                 
               <Panel>

src/Avalonia.Themes.Default/TreeView.xaml

@@ -7,7 +7,7 @@
     <ControlTemplate>
       <Border BorderBrush="{TemplateBinding BorderBrush}"
               BorderThickness="{TemplateBinding BorderThickness}">
-        <ScrollViewer CanScrollHorizontally="True" Background="{TemplateBinding Background}">
+        <ScrollViewer Background="{TemplateBinding Background}">
           <ItemsPresenter Name="PART_ItemsPresenter"
                           Items="{TemplateBinding Items}"
                           ItemsPanel="{TemplateBinding ItemsPanel}"

src/Avalonia.Visuals/Rendering/DeferredRenderer.cs

@@ -415,7 +415,7 @@ namespace Avalonia.Rendering
                     if (!_updateQueued && (_dirty == null || _dirty.Count > 0))
                     {
                         _updateQueued = true;
-                        _dispatcher.InvokeAsync(UpdateScene, DispatcherPriority.Render);
+                        _dispatcher.Post(UpdateScene, DispatcherPriority.Render);
                     }
 
                     Scene scene = null;

src/Avalonia.Visuals/Rendering/ImmediateRenderer.cs

@@ -169,7 +169,7 @@ namespace Avalonia.Rendering
         {
             foreach (var e in visual.GetSelfAndVisualDescendants())
             {
-                BoundsTracker.SetTransformedBounds((Visual)visual, null);
+                visual.TransformedBounds = null;
             }
         }
 
@@ -197,7 +197,7 @@ namespace Avalonia.Rendering
 
             if (filter?.Invoke(visual) != false)
             {
-                bool containsPoint = BoundsTracker.GetTransformedBounds((Visual)visual)?.Contains(p) == true;
+                bool containsPoint = visual.TransformedBounds?.Contains(p) == true;
 
                 if ((containsPoint || !visual.ClipToBounds) && visual.VisualChildren.Count > 0)
                 {
@@ -257,10 +257,7 @@ namespace Avalonia.Rendering
                         new TransformedBounds(bounds, new Rect(), context.CurrentContainerTransform);
 #pragma warning restore 0618
 
-                    if (visual is Visual)
-                    {
-                        BoundsTracker.SetTransformedBounds((Visual)visual, transformed);
-                    }
+                    visual.TransformedBounds = transformed;
 
                     foreach (var child in visual.VisualChildren.OrderBy(x => x, ZIndexComparer.Instance))
                     {

src/Avalonia.Visuals/Rendering/SceneGraph/SceneBuilder.cs

@@ -209,11 +209,8 @@ namespace Avalonia.Rendering.SceneGraph
                     }
                     catch { }
 
-                    if (visual is Visual)
-                    {
-                        var transformed = new TransformedBounds(new Rect(visual.Bounds.Size), clip, node.Transform);
-                        BoundsTracker.SetTransformedBounds((Visual)visual, transformed);
-                    }
+                    var transformed = new TransformedBounds(new Rect(visual.Bounds.Size), clip, node.Transform);
+                    visual.TransformedBounds = transformed;
 
                     if (forceRecurse)
                     {
@@ -279,10 +276,7 @@ namespace Avalonia.Rendering.SceneGraph
 
             scene.Layers[node.LayerRoot].Dirty.Add(node.Bounds);
 
-            if (node.Visual is Visual v)
-            {
-                BoundsTracker.SetTransformedBounds(v, null);
-            }
+            node.Visual.TransformedBounds = null;
 
             foreach (VisualNode child in node.Children)
             {

src/Avalonia.Visuals/Visual.cs

@@ -32,6 +32,11 @@ namespace Avalonia
         public static readonly DirectProperty<Visual, Rect> BoundsProperty =
             AvaloniaProperty.RegisterDirect<Visual, Rect>(nameof(Bounds), o => o.Bounds);
 
+        public static readonly DirectProperty<Visual, TransformedBounds?> TransformedBoundsProperty =
+            AvaloniaProperty.RegisterDirect<Visual, TransformedBounds?>(
+                nameof(TransformedBounds),
+                o => o.TransformedBounds);
+
         /// <summary>
         /// Defines the <see cref="ClipToBounds"/> property.
         /// </summary>
@@ -87,6 +92,7 @@ namespace Avalonia
             AvaloniaProperty.Register<Visual, int>(nameof(ZIndex));
 
         private Rect _bounds;
+        private TransformedBounds? _transformedBounds;
         private IRenderRoot _visualRoot;
         private IVisual _visualParent;
 
@@ -135,6 +141,11 @@ namespace Avalonia
             protected set { SetAndRaise(BoundsProperty, ref _bounds, value); }
         }
 
+        /// <summary>
+        /// Gets the bounds of the control relative to the window, accounting for rendering transforms.
+        /// </summary>
+        public TransformedBounds? TransformedBounds => _transformedBounds;
+
         /// <summary>
         /// Gets a value indicating whether the control should be clipped to its bounds.
         /// </summary>
@@ -253,6 +264,12 @@ namespace Avalonia
         /// Gets the root of the visual tree, if the control is attached to a visual tree.
         /// </summary>
         IRenderRoot IVisual.VisualRoot => VisualRoot;
+        
+        TransformedBounds? IVisual.TransformedBounds
+        {
+            get { return _transformedBounds; }
+            set { SetAndRaise(TransformedBoundsProperty, ref _transformedBounds, value); }
+        }
 
         /// <summary>
         /// Invalidates the visual and queues a repaint.

src/Avalonia.Visuals/VisualTree/BoundsTracker.cs

@@ -1,51 +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;
-
-namespace Avalonia.VisualTree
-{
-    /// <summary>
-    /// Tracks the bounds of a control.
-    /// </summary>
-    /// <remarks>
-    /// This class is used to track a controls's bounds for hit testing.
-    /// TODO: This shouldn't be implemented as an attached property: it would be more performant
-    /// to just store bounds in some sort of central repository.
-    /// </remarks>
-    public class BoundsTracker
-    {
-        /// <summary>
-        /// Defines the TransformedBounds attached property.
-        /// </summary>
-        private static AttachedProperty<TransformedBounds?> TransformedBoundsProperty =
-            AvaloniaProperty.RegisterAttached<BoundsTracker, Visual, TransformedBounds?>("TransformedBounds");
-
-        /// <summary>
-        /// Starts tracking the specified visual.
-        /// </summary>
-        /// <param name="visual">The visual.</param>
-        /// <returns>An observable that returns the tracked bounds.</returns>
-        public IObservable<TransformedBounds?> Track(Visual visual)
-        {
-            return visual.GetObservable(TransformedBoundsProperty);
-        }
-
-        /// <summary>
-        /// Sets the transformed bounds of the visual.
-        /// </summary>
-        /// <param name="visual">The visual.</param>
-        /// <param name="value">The transformed bounds.</param>
-        internal static void SetTransformedBounds(Visual visual, TransformedBounds? value)
-        {
-            visual.SetValue(TransformedBoundsProperty, value);
-        }
-
-        /// <summary>
-        /// Gets the transformed bounds of the visual.
-        /// </summary>
-        /// <param name="visual">The visual.</param>
-        /// <returns>The transformed bounds or null if the visual is not visible.</returns>
-        public static TransformedBounds? GetTransformedBounds(Visual visual) => visual.GetValue(TransformedBoundsProperty);
-    }
-}

src/Avalonia.Visuals/VisualTree/IVisual.cs

@@ -36,6 +36,11 @@ namespace Avalonia.VisualTree
         /// </summary>
         Rect Bounds { get; }
 
+        /// <summary>
+        /// Gets the bounds of the control relative to the window, accounting for rendering transforms.
+        /// </summary>
+        TransformedBounds? TransformedBounds { get; set; }
+
         /// <summary>
         /// Gets a value indicating whether the control should be clipped to its bounds.
         /// </summary>

src/Gtk/Avalonia.Gtk3/WindowBaseImpl.cs

@@ -351,7 +351,7 @@ namespace Avalonia.Gtk3
 
         void OnInput(RawInputEventArgs args)
         {
-            Dispatcher.UIThread.InvokeAsync(() => Input?.Invoke(args), DispatcherPriority.Input);
+            Dispatcher.UIThread.Post(() => Input?.Invoke(args), DispatcherPriority.Input);
         }
 
         public Point PointToClient(Point point)

src/Linux/Avalonia.LinuxFramebuffer/FramebufferToplevelImpl.cs

@@ -41,7 +41,7 @@ namespace Avalonia.LinuxFramebuffer
             if(_renderQueued)
                 return;
             _renderQueued = true;
-            Dispatcher.UIThread.InvokeAsync(() =>
+            Dispatcher.UIThread.Post(() =>
             {
                 Paint?.Invoke(new Rect(default(Point), ClientSize));
                 _renderQueued = false;

src/Linux/Avalonia.LinuxFramebuffer/LinuxFramebufferPlatform.cs

@@ -62,7 +62,7 @@ public static class LinuxFramebufferPlatformExtensions
 
         public TokenClosable(CancellationToken token)
         {
-            token.Register(() => Dispatcher.UIThread.InvokeAsync(() => Closed?.Invoke(this, new EventArgs())));
+            token.Register(() => Dispatcher.UIThread.Post(() => Closed?.Invoke(this, new EventArgs())));
         }
     }
 

src/Markup/Avalonia.Markup/Data/Plugins/AvaloniaPropertyAccessorPlugin.cs

@@ -104,7 +104,7 @@ namespace Avalonia.Markup.Data.Plugins
 
             protected override void SubscribeCore(IObserver<object> observer)
             {
-                _subscription = Instance.GetWeakObservable(_property).Subscribe(observer);
+                _subscription = Instance?.GetWeakObservable(_property).Subscribe(observer);
             }
         }
     }

src/OSX/Avalonia.MonoMac/TopLevelImpl.cs

@@ -107,7 +107,7 @@ namespace Avalonia.MonoMac
                     if (_nonUiRedrawQueued)
                         return;
                     _nonUiRedrawQueued = true;
-                    Dispatcher.UIThread.InvokeAsync(
+                    Dispatcher.UIThread.Post(
                         () =>
                         {
                             lock (SyncRoot)

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

@@ -281,6 +281,8 @@ namespace Avalonia.Controls.UnitTests.Presenters
 
             var scroller = new TestScroller
             {
+                CanHorizontallyScroll = false,
+                CanVerticallyScroll = true,
                 Content = result = new TestItemsPresenter(useContainers)
                 {
                     Items = items,

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

@@ -998,6 +998,8 @@ namespace Avalonia.Controls.UnitTests.Presenters
 
             var scroller = new TestScroller
             {
+                CanHorizontallyScroll = true,
+                CanVerticallyScroll = true,
                 Content = result = new TestItemsPresenter(useContainers)
                 {
                     Items = items,

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

@@ -5,6 +5,7 @@ using System;
 using System.Collections.Generic;
 using System.Reactive.Linq;
 using Avalonia.Controls.Presenters;
+using Avalonia.Controls.Primitives;
 using Avalonia.Layout;
 using Xunit;
 
@@ -118,6 +119,8 @@ namespace Avalonia.Controls.UnitTests.Presenters
             TestControl content;
             var target = new ScrollContentPresenter
             {
+                CanHorizontallyScroll = true,
+                CanVerticallyScroll = true,
                 Content = content = new TestControl(),
             };
 
@@ -134,6 +137,8 @@ namespace Avalonia.Controls.UnitTests.Presenters
             Border content;
             var target = new ScrollContentPresenter
             {
+                CanHorizontallyScroll = true,
+                CanVerticallyScroll = true,
                 Content = content = new Border
                 {
                     Width = 150,
@@ -155,8 +160,8 @@ namespace Avalonia.Controls.UnitTests.Presenters
             var child = new TestControl();
             var target = new ScrollContentPresenter
             {
+                CanVerticallyScroll = true,
                 Content = child,
-                [ScrollContentPresenter.CanScrollHorizontallyProperty] = false,
             };
 
             target.UpdateChild();
@@ -171,6 +176,8 @@ namespace Avalonia.Controls.UnitTests.Presenters
             var child = new TestControl();
             var target = new ScrollContentPresenter
             {
+                CanHorizontallyScroll = true,
+                CanVerticallyScroll = true,
                 Content = child,
             };
 
@@ -246,6 +253,8 @@ namespace Avalonia.Controls.UnitTests.Presenters
             Border border;
             var target = new ScrollContentPresenter
             {
+                CanHorizontallyScroll = true,
+                CanVerticallyScroll = true,
                 Width = 100,
                 Height = 100,
                 Content = new Decorator

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

@@ -13,7 +13,7 @@ namespace Avalonia.Controls.UnitTests
     public class ScrollContentPresenterTests_ILogicalScrollable
     {
         [Fact]
-        public void Measure_Should_Pass_Unchanged_Bounds_To_IScrollable()
+        public void Measure_Should_Pass_Unchanged_Bounds_To_ILogicalScrollable()
         {
             var scrollable = new TestScrollable();
             var target = new ScrollContentPresenter
@@ -28,7 +28,7 @@ namespace Avalonia.Controls.UnitTests
         }
 
         [Fact]
-        public void Arrange_Should_Not_Offset_IScrollable_Bounds()
+        public void Arrange_Should_Not_Offset_ILogicalScrollable_Bounds()
         {
             var scrollable = new TestScrollable
             {
@@ -50,7 +50,7 @@ namespace Avalonia.Controls.UnitTests
         }
 
         [Fact]
-        public void Arrange_Should_Offset_IScrollable_Bounds_When_Logical_Scroll_Disabled()
+        public void Arrange_Should_Offset_ILogicalScrollable_Bounds_When_Logical_Scroll_Disabled()
         {
             var scrollable = new TestScrollable
             {
@@ -59,6 +59,8 @@ namespace Avalonia.Controls.UnitTests
 
             var target = new ScrollContentPresenter
             {
+                CanHorizontallyScroll = true,
+                CanVerticallyScroll = true,
                 Content = scrollable,
                 Offset = new Vector(25, 25),
             };
@@ -71,7 +73,7 @@ namespace Avalonia.Controls.UnitTests
         }
 
         [Fact]
-        public void Arrange_Should_Not_Set_Viewport_And_Extent_With_IScrollable()
+        public void Arrange_Should_Not_Set_Viewport_And_Extent_With_ILogicalScrollable()
         {
             var target = new ScrollContentPresenter
             {
@@ -122,7 +124,7 @@ namespace Avalonia.Controls.UnitTests
         }
 
         [Fact]
-        public void Extent_Offset_And_Viewport_Should_Be_Read_From_IScrollable()
+        public void Extent_Offset_And_Viewport_Should_Be_Read_From_ILogicalScrollable()
         {
             var scrollable = new TestScrollable
             {
@@ -152,7 +154,7 @@ namespace Avalonia.Controls.UnitTests
         }
 
         [Fact]
-        public void Offset_Should_Be_Written_To_IScrollable()
+        public void Offset_Should_Be_Written_To_ILogicalScrollable()
         {
             var scrollable = new TestScrollable
             {
@@ -172,7 +174,7 @@ namespace Avalonia.Controls.UnitTests
         }
 
         [Fact]
-        public void Offset_Should_Not_Be_Written_To_IScrollable_After_Removal()
+        public void Offset_Should_Not_Be_Written_To_ILogicalScrollable_After_Removal()
         {
             var scrollable = new TestScrollable
             {
@@ -203,6 +205,8 @@ namespace Avalonia.Controls.UnitTests
 
             var target = new ScrollContentPresenter
             {
+                CanHorizontallyScroll = true,
+                CanVerticallyScroll = true,
                 Content = scrollable,
             };
 
@@ -253,6 +257,8 @@ namespace Avalonia.Controls.UnitTests
 
             var target = new ScrollContentPresenter
             {
+                CanHorizontallyScroll = true,
+                CanVerticallyScroll = true,
                 Content = logicalScrollable,
             };
 
@@ -286,12 +292,38 @@ namespace Avalonia.Controls.UnitTests
             Assert.Equal(new Rect(0, 0, 100, 100), logicalScrollable.Bounds);
         }
 
+        [Fact]
+        public void Should_Set_ILogicalScrolable_CanHorizontallyScroll()
+        {
+            var logicalScrollable = new TestScrollable();
+            var target = new ScrollContentPresenter { Content = logicalScrollable };
+
+            target.UpdateChild();
+            Assert.False(logicalScrollable.CanHorizontallyScroll);
+            target.CanHorizontallyScroll = true;
+            Assert.True(logicalScrollable.CanHorizontallyScroll);
+        }
+
+        [Fact]
+        public void Should_Set_ILogicalScrolable_CanVerticallyScroll()
+        {
+            var logicalScrollable = new TestScrollable();
+            var target = new ScrollContentPresenter { Content = logicalScrollable };
+
+            target.UpdateChild();
+            Assert.False(logicalScrollable.CanVerticallyScroll);
+            target.CanVerticallyScroll = true;
+            Assert.True(logicalScrollable.CanVerticallyScroll);
+        }
+
         private class TestScrollable : Control, ILogicalScrollable
         {
             private Size _extent;
             private Vector _offset;
             private Size _viewport;
 
+            public bool CanHorizontallyScroll { get; set; }
+            public bool CanVerticallyScroll { get; set; }
             public bool IsLogicalScrollEnabled { get; set; } = true;
             public Size AvailableSize { get; private set; }
             public Action InvalidateScroll { get; set; }

tests/Avalonia.Controls.UnitTests/ScrollViewerTests.cs

@@ -1,6 +1,8 @@
 // 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.Controls.Presenters;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
@@ -25,6 +27,32 @@ namespace Avalonia.Controls.UnitTests
             Assert.IsType<TextBlock>(target.Presenter.Child);
         }
 
+        [Fact]
+        public void CanHorizontallyScroll_Should_Track_HorizontalScrollBarVisibility()
+        {
+            var target = new ScrollViewer();
+            var values = new List<bool>();
+
+            target.GetObservable(ScrollViewer.CanHorizontallyScrollProperty).Subscribe(x => values.Add(x));
+            target.HorizontalScrollBarVisibility = ScrollBarVisibility.Disabled;
+            target.HorizontalScrollBarVisibility = ScrollBarVisibility.Auto;
+
+            Assert.Equal(new[] { true, false, true }, values);
+        }
+
+        [Fact]
+        public void CanVerticallyScroll_Should_Track_VerticalScrollBarVisibility()
+        {
+            var target = new ScrollViewer();
+            var values = new List<bool>();
+
+            target.GetObservable(ScrollViewer.CanVerticallyScrollProperty).Subscribe(x => values.Add(x));
+            target.VerticalScrollBarVisibility = ScrollBarVisibility.Disabled;
+            target.VerticalScrollBarVisibility = ScrollBarVisibility.Auto;
+
+            Assert.Equal(new[] { true, false, true }, values);
+        }
+
         [Fact]
         public void Offset_Should_Be_Coerced_To_Viewport()
         {
@@ -59,7 +87,7 @@ namespace Avalonia.Controls.UnitTests
                         [~~ScrollContentPresenter.ExtentProperty] = control[~~ScrollViewer.ExtentProperty],
                         [~~ScrollContentPresenter.OffsetProperty] = control[~~ScrollViewer.OffsetProperty],
                         [~~ScrollContentPresenter.ViewportProperty] = control[~~ScrollViewer.ViewportProperty],
-                        [~ScrollContentPresenter.CanScrollHorizontallyProperty] = control[~ScrollViewer.CanScrollHorizontallyProperty],
+                        [~ScrollContentPresenter.CanHorizontallyScrollProperty] = control[~ScrollViewer.CanHorizontallyScrollProperty],
                     },
                     new ScrollBar
                     {

tests/Avalonia.Layout.UnitTests/FullLayoutTests.cs

@@ -85,7 +85,7 @@ namespace Avalonia.Layout.UnitTests
                     {
                         Width = 200,
                         Height = 200,
-                        CanScrollHorizontally = true,
+                        HorizontalScrollBarVisibility = ScrollBarVisibility.Auto,
                         HorizontalAlignment = HorizontalAlignment.Center,
                         VerticalAlignment = VerticalAlignment.Center,
                         Content = textBlock = new TextBlock

tests/Avalonia.Markup.UnitTests/Data/ExpressionObserverTests_Observable.cs

@@ -103,20 +103,22 @@ namespace Avalonia.Markup.UnitTests.Data
         {
             using (var sync = UnitTestSynchronizationContext.Begin())
             {
-                var data = new Class1();
-                var target = new ExpressionObserver(data, "Next^.Foo", true);
+                var data1 = new Class1();
+                var data2 = new Class2("foo");
+                var target = new ExpressionObserver(data1, "Next^.Foo", true);
                 var result = new List<object>();
 
                 var sub = target.Subscribe(x => result.Add(x));
-                data.Next.OnNext(new Class2("foo"));
+                data1.Next.OnNext(data2);
                 sync.ExecutePostedCallbacks();
 
                 Assert.Equal(new[] { new BindingNotification("foo") }, result);
 
                 sub.Dispose();
-                Assert.Equal(0, data.PropertyChangedSubscriptionCount);
+                Assert.Equal(0, data1.PropertyChangedSubscriptionCount);
 
-                GC.KeepAlive(data);
+                GC.KeepAlive(data1);
+                GC.KeepAlive(data2);
             }
         }
 

tests/Avalonia.UnitTests/ImmediateDispatcher.cs

@@ -14,12 +14,12 @@ namespace Avalonia.UnitTests
             return true;
         }
 
-        public void InvokeAsync(Action action, DispatcherPriority priority = DispatcherPriority.Normal)
+        public void Post(Action action, DispatcherPriority priority = DispatcherPriority.Normal)
         {
             action();
         }
 
-        public Task InvokeTaskAsync(Action action, DispatcherPriority priority = DispatcherPriority.Normal)
+        public Task InvokeAsync(Action action, DispatcherPriority priority = DispatcherPriority.Normal)
         {
             action();
             return Task.FromResult<object>(null);

tests/Avalonia.Visuals.UnitTests/Rendering/DeferredRendererTests.cs

@@ -24,13 +24,13 @@ namespace Avalonia.Visuals.UnitTests.Rendering
             var root = new TestRoot();
 
             var dispatcher = new Mock<IDispatcher>();
-            dispatcher.Setup(x => x.InvokeAsync(It.IsAny<Action>(), DispatcherPriority.Render))
+            dispatcher.Setup(x => x.Post(It.IsAny<Action>(), DispatcherPriority.Render))
                 .Callback<Action, DispatcherPriority>((a, p) => a());
 
             CreateTargetAndRunFrame(root, dispatcher: dispatcher.Object);
 
             dispatcher.Verify(x => 
-                x.InvokeAsync(
+                x.Post(
                     It.Is<Action>(a => a.Method.Name == "UpdateScene"),
                     DispatcherPriority.Render));
         }

tests/Avalonia.Visuals.UnitTests/Rendering/DeferredRendererTests_HitTesting.cs

@@ -372,6 +372,8 @@ namespace Avalonia.Visuals.UnitTests.Rendering
                                 Margin = new Thickness(0, 100, 0, 0),
                                 Child = scroll = new ScrollContentPresenter()
                                 {
+                                    CanHorizontallyScroll = true,
+                                    CanVerticallyScroll = true,
                                     Content = new StackPanel()
                                     {
                                         Children =

tests/Avalonia.Visuals.UnitTests/Rendering/ImmediateRendererTests_HitTesting.cs

@@ -357,6 +357,8 @@ namespace Avalonia.Visuals.UnitTests.Rendering
                                 Margin = new Thickness(0, 100, 0, 0),
                                 Child = scroll = new ScrollContentPresenter()
                                 {
+                                    CanHorizontallyScroll = true,
+                                    CanVerticallyScroll = true,
                                     Content = new StackPanel()
                                     {
                                         Children =

tests/Avalonia.Visuals.UnitTests/VisualTree/BoundsTrackerTests.cs → tests/Avalonia.Visuals.UnitTests/VisualTree/TransformedBoundsTests.cs

@@ -17,14 +17,13 @@ using Avalonia.Platform;
 
 namespace Avalonia.Visuals.UnitTests.VisualTree
 {
-    public class BoundsTrackerTests
+    public class TransformedBoundsTests
     {
         [Fact]
         public void Should_Track_Bounds()
         {
             using (UnitTestApplication.Start(TestServices.StyledWindow))
             {
-                var target = new BoundsTracker();
                 var control = default(Rectangle);
                 var tree = new Decorator
                 {
@@ -46,7 +45,7 @@ namespace Avalonia.Visuals.UnitTests.VisualTree
                 tree.Arrange(new Rect(0, 0, 100, 100));
                 ImmediateRenderer.Render(tree, context);
 
-                var track = target.Track(control);
+                var track = control.GetObservable(Visual.TransformedBoundsProperty);
                 var results = new List<TransformedBounds?>();
                 track.Subscribe(results.Add);