diff --git a/src/Avalonia.Base/ApiCompatBaseline.txt b/src/Avalonia.Base/ApiCompatBaseline.txt
new file mode 100644
index 0000000000..4668a572c5
--- /dev/null
+++ b/src/Avalonia.Base/ApiCompatBaseline.txt
@@ -0,0 +1,3 @@
+Compat issues with assembly Avalonia.Base:
+CannotAddAbstractMembers : Member 'protected System.IObservable<Avalonia.AvaloniaPropertyChangedEventArgs> Avalonia.AvaloniaProperty.GetChanged()' is abstract in the implementation but is missing in the contract.
+Total Issues: 1
diff --git a/src/Avalonia.Base/AvaloniaProperty.cs b/src/Avalonia.Base/AvaloniaProperty.cs
index 39391490b0..3ae0445e9b 100644
--- a/src/Avalonia.Base/AvaloniaProperty.cs
+++ b/src/Avalonia.Base/AvaloniaProperty.cs
@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Reactive.Subjects;
 using Avalonia.Data;
 using Avalonia.Data.Core;
 using Avalonia.Utilities;
@@ -18,7 +17,6 @@ namespace Avalonia
         public static readonly object UnsetValue = new UnsetValueType();
 
         private static int s_nextId;
-        private readonly Subject<AvaloniaPropertyChangedEventArgs> _changed;
         private readonly PropertyMetadata _defaultMetadata;
         private readonly Dictionary<Type, PropertyMetadata> _metadata;
         private readonly Dictionary<Type, PropertyMetadata> _metadataCache = new Dictionary<Type, PropertyMetadata>();
@@ -50,7 +48,6 @@ namespace Avalonia
                 throw new ArgumentException("'name' may not contain periods.");
             }
 
-            _changed = new Subject<AvaloniaPropertyChangedEventArgs>();
             _metadata = new Dictionary<Type, PropertyMetadata>();
 
             Name = name;
@@ -77,7 +74,6 @@ namespace Avalonia
             Contract.Requires<ArgumentNullException>(source != null);
             Contract.Requires<ArgumentNullException>(ownerType != null);
 
-            _changed = source._changed;
             _metadata = new Dictionary<Type, PropertyMetadata>();
 
             Name = source.Name;
@@ -139,7 +135,7 @@ namespace Avalonia
         /// An observable that is fired when this property changes on any
         /// <see cref="AvaloniaObject"/> instance.
         /// </value>
-        public IObservable<AvaloniaPropertyChangedEventArgs> Changed => _changed;
+        public IObservable<AvaloniaPropertyChangedEventArgs> Changed => GetChanged();
 
         /// <summary>
         /// Gets a method that gets called before and after the property starts being notified on an
@@ -474,15 +470,6 @@ namespace Avalonia
         public abstract void Accept<TData>(IAvaloniaPropertyVisitor<TData> vistor, ref TData data)
             where TData : struct;
 
-        /// <summary>
-        /// Notifies the <see cref="Changed"/> observable.
-        /// </summary>
-        /// <param name="e">The observable arguments.</param>
-        internal void NotifyChanged(AvaloniaPropertyChangedEventArgs e)
-        {
-            _changed.OnNext(e);
-        }
-
         /// <summary>
         /// Routes an untyped ClearValue call to a typed call.
         /// </summary>
@@ -553,6 +540,8 @@ namespace Avalonia
             _hasMetadataOverrides = true;
         }
 
+        protected abstract IObservable<AvaloniaPropertyChangedEventArgs> GetChanged();
+
         private PropertyMetadata GetMetadataWithOverrides(Type type)
         {
             if (type is null)
diff --git a/src/Avalonia.Base/AvaloniaProperty`1.cs b/src/Avalonia.Base/AvaloniaProperty`1.cs
index 2f26d855f2..d5549e979b 100644
--- a/src/Avalonia.Base/AvaloniaProperty`1.cs
+++ b/src/Avalonia.Base/AvaloniaProperty`1.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Reactive.Subjects;
 using Avalonia.Data;
 using Avalonia.Utilities;
 
@@ -10,6 +11,8 @@ namespace Avalonia
     /// <typeparam name="TValue">The value type of the property.</typeparam>
     public abstract class AvaloniaProperty<TValue> : AvaloniaProperty
     {
+        private readonly Subject<AvaloniaPropertyChangedEventArgs<TValue>> _changed;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="AvaloniaProperty{TValue}"/> class.
         /// </summary>
@@ -24,22 +27,61 @@ namespace Avalonia
             Action<IAvaloniaObject, bool> notifying = null)
             : base(name, typeof(TValue), ownerType, metadata, notifying)
         {
+            _changed = new Subject<AvaloniaPropertyChangedEventArgs<TValue>>();
         }
 
         /// <summary>
-        /// Initializes a new instance of the <see cref="AvaloniaProperty"/> class.
+        /// Initializes a new instance of the <see cref="AvaloniaProperty{TValue}"/> class.
         /// </summary>
         /// <param name="source">The property to copy.</param>
         /// <param name="ownerType">The new owner type.</param>
         /// <param name="metadata">Optional overridden metadata.</param>
+        [Obsolete("Use constructor with AvaloniaProperty<TValue> instead.", true)]
         protected AvaloniaProperty(
-            AvaloniaProperty source, 
-            Type ownerType, 
+            AvaloniaProperty source,
+            Type ownerType,
+            PropertyMetadata metadata)
+            : this(source as AvaloniaProperty<TValue> ?? throw new InvalidOperationException(), ownerType, metadata)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="AvaloniaProperty{TValue}"/> class.
+        /// </summary>
+        /// <param name="source">The property to copy.</param>
+        /// <param name="ownerType">The new owner type.</param>
+        /// <param name="metadata">Optional overridden metadata.</param>
+        protected AvaloniaProperty(
+            AvaloniaProperty<TValue> source,
+            Type ownerType,
             PropertyMetadata metadata)
             : base(source, ownerType, metadata)
         {
+            _changed = source._changed;
+        }
+
+        /// <summary>
+        /// Gets an observable that is fired when this property changes on any
+        /// <see cref="AvaloniaObject"/> instance.
+        /// </summary>
+        /// <value>
+        /// An observable that is fired when this property changes on any
+        /// <see cref="AvaloniaObject"/> instance.
+        /// </value>
+
+        public new IObservable<AvaloniaPropertyChangedEventArgs<TValue>> Changed => _changed;
+
+        /// <summary>
+        /// Notifies the <see cref="Changed"/> observable.
+        /// </summary>
+        /// <param name="e">The observable arguments.</param>
+        internal void NotifyChanged(AvaloniaPropertyChangedEventArgs<TValue> e)
+        {
+            _changed.OnNext(e);
         }
 
+        protected override IObservable<AvaloniaPropertyChangedEventArgs> GetChanged() => Changed;
+
         protected BindingValue<object> TryConvert(object value)
         {
             if (value == UnsetValue)
diff --git a/src/Avalonia.Base/DirectPropertyBase.cs b/src/Avalonia.Base/DirectPropertyBase.cs
index dbc2625b86..a2f113adb7 100644
--- a/src/Avalonia.Base/DirectPropertyBase.cs
+++ b/src/Avalonia.Base/DirectPropertyBase.cs
@@ -32,15 +32,30 @@ namespace Avalonia
         }
 
         /// <summary>
-        /// Initializes a new instance of the <see cref="AvaloniaProperty"/> class.
+        /// Initializes a new instance of the <see cref="DirectPropertyBase{TValue}"/> class.
         /// </summary>
         /// <param name="source">The property to copy.</param>
         /// <param name="ownerType">The new owner type.</param>
         /// <param name="metadata">Optional overridden metadata.</param>
+        [Obsolete("Use constructor with DirectPropertyBase<TValue> instead.", true)]
         protected DirectPropertyBase(
             AvaloniaProperty source,
             Type ownerType,
             PropertyMetadata metadata)
+            : this(source as DirectPropertyBase<TValue> ?? throw new InvalidOperationException(), ownerType, metadata)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DirectPropertyBase{TValue}"/> class.
+        /// </summary>
+        /// <param name="source">The property to copy.</param>
+        /// <param name="ownerType">The new owner type.</param>
+        /// <param name="metadata">Optional overridden metadata.</param>
+        protected DirectPropertyBase(
+            DirectPropertyBase<TValue> source,
+            Type ownerType,
+            PropertyMetadata metadata)
             : base(source, ownerType, metadata)
         {
         }
diff --git a/src/Avalonia.Controls/Mixins/SelectableMixin.cs b/src/Avalonia.Controls/Mixins/SelectableMixin.cs
index d2586ab6e8..c9e2b684cb 100644
--- a/src/Avalonia.Controls/Mixins/SelectableMixin.cs
+++ b/src/Avalonia.Controls/Mixins/SelectableMixin.cs
@@ -48,7 +48,7 @@ namespace Avalonia.Controls.Mixins
 
                 if (sender != null)
                 {
-                    ((IPseudoClasses)sender.Classes).Set(":selected", (bool)x.NewValue);
+                    ((IPseudoClasses)sender.Classes).Set(":selected", x.NewValue.GetValueOrDefault());
 
                     sender.RaiseEvent(new RoutedEventArgs
                     {
@@ -58,4 +58,4 @@ namespace Avalonia.Controls.Mixins
             });
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Avalonia.Controls/NativeMenu.Export.cs b/src/Avalonia.Controls/NativeMenu.Export.cs
index 776e9d2171..0349df842b 100644
--- a/src/Avalonia.Controls/NativeMenu.Export.cs
+++ b/src/Avalonia.Controls/NativeMenu.Export.cs
@@ -77,7 +77,7 @@ namespace Avalonia.Controls
             {
                 if (args.Sender is TopLevel tl)
                 {
-                    GetInfo(tl).Exporter?.SetNativeMenu((NativeMenu)args.NewValue);
+                    GetInfo(tl).Exporter?.SetNativeMenu(args.NewValue.GetValueOrDefault());
                 }
             });
         }
diff --git a/src/Avalonia.Controls/NativeMenuItem.cs b/src/Avalonia.Controls/NativeMenuItem.cs
index 4c94d82eb4..a0fec9e677 100644
--- a/src/Avalonia.Controls/NativeMenuItem.cs
+++ b/src/Avalonia.Controls/NativeMenuItem.cs
@@ -23,7 +23,7 @@ namespace Avalonia.Controls
             MenuProperty.Changed.Subscribe(args =>
             {
                 var item = (NativeMenuItem)args.Sender;
-                var value = (NativeMenu)args.NewValue;
+                var value = args.NewValue.GetValueOrDefault();
                 if (value.Parent != null && value.Parent != item)
                     throw new InvalidOperationException("NativeMenu already has a parent");
                 value.Parent = item;
diff --git a/src/Avalonia.Controls/Presenters/TextPresenter.cs b/src/Avalonia.Controls/Presenters/TextPresenter.cs
index cb7bee1d33..f5115a2f7c 100644
--- a/src/Avalonia.Controls/Presenters/TextPresenter.cs
+++ b/src/Avalonia.Controls/Presenters/TextPresenter.cs
@@ -82,7 +82,7 @@ namespace Avalonia.Controls.Presenters
                 TextAlignmentProperty, TextWrappingProperty, TextBlock.FontSizeProperty,
                 TextBlock.FontStyleProperty, TextBlock.FontWeightProperty, TextBlock.FontFamilyProperty);
 
-            Observable.Merge(TextProperty.Changed, TextBlock.ForegroundProperty.Changed,
+            Observable.Merge<AvaloniaPropertyChangedEventArgs>(TextProperty.Changed, TextBlock.ForegroundProperty.Changed,
                 TextAlignmentProperty.Changed, TextWrappingProperty.Changed,
                 TextBlock.FontSizeProperty.Changed, TextBlock.FontStyleProperty.Changed, 
                 TextBlock.FontWeightProperty.Changed, TextBlock.FontFamilyProperty.Changed,
diff --git a/src/Avalonia.Controls/Primitives/IPopupHost.cs b/src/Avalonia.Controls/Primitives/IPopupHost.cs
index e424bf683d..82a49c4189 100644
--- a/src/Avalonia.Controls/Primitives/IPopupHost.cs
+++ b/src/Avalonia.Controls/Primitives/IPopupHost.cs
@@ -1,6 +1,7 @@
 using System;
 using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Primitives.PopupPositioning;
+using Avalonia.Input;
 using Avalonia.VisualTree;
 
 namespace Avalonia.Controls.Primitives
@@ -13,7 +14,7 @@ namespace Avalonia.Controls.Primitives
     /// (<see cref="PopupRoot"/>) or an <see cref="OverlayPopupHost"/> which is created
     /// on an <see cref="OverlayLayer"/>.
     /// </remarks>
-    public interface IPopupHost : IDisposable
+    public interface IPopupHost : IDisposable, IFocusScope
     {
         /// <summary>
         /// Sets the control to display in the popup.
diff --git a/src/Avalonia.Controls/TextBlock.cs b/src/Avalonia.Controls/TextBlock.cs
index 3b9e9c4751..d8477840af 100644
--- a/src/Avalonia.Controls/TextBlock.cs
+++ b/src/Avalonia.Controls/TextBlock.cs
@@ -138,7 +138,7 @@ namespace Avalonia.Controls
                 FontStyleProperty, TextWrappingProperty, FontFamilyProperty,
                 TextTrimmingProperty, TextProperty, PaddingProperty, LineHeightProperty, MaxLinesProperty);
 
-            Observable.Merge(TextProperty.Changed, ForegroundProperty.Changed,
+            Observable.Merge<AvaloniaPropertyChangedEventArgs>(TextProperty.Changed, ForegroundProperty.Changed,
                 TextAlignmentProperty.Changed, TextWrappingProperty.Changed,
                 TextTrimmingProperty.Changed, FontSizeProperty.Changed,
                 FontStyleProperty.Changed, FontWeightProperty.Changed,
diff --git a/tests/Avalonia.Base.UnitTests/AvaloniaObjectTests_Direct.cs b/tests/Avalonia.Base.UnitTests/AvaloniaObjectTests_Direct.cs
index 81a8de1046..20172eea88 100644
--- a/tests/Avalonia.Base.UnitTests/AvaloniaObjectTests_Direct.cs
+++ b/tests/Avalonia.Base.UnitTests/AvaloniaObjectTests_Direct.cs
@@ -94,8 +94,8 @@ namespace Avalonia.Base.UnitTests
 
             Class1.FooProperty.Changed.Subscribe(e =>
                 raised = e.Property == Class1.FooProperty &&
-                         (string)e.OldValue == "initial" &&
-                         (string)e.NewValue == "newvalue" &&
+                         e.OldValue.GetValueOrDefault() == "initial" &&
+                         e.NewValue.GetValueOrDefault() == "newvalue" &&
                          e.Priority == BindingPriority.LocalValue);
 
             target.SetValue(Class1.FooProperty, "newvalue");
diff --git a/tests/Avalonia.Base.UnitTests/AvaloniaPropertyTests.cs b/tests/Avalonia.Base.UnitTests/AvaloniaPropertyTests.cs
index d7f927372e..8e5d8b7be2 100644
--- a/tests/Avalonia.Base.UnitTests/AvaloniaPropertyTests.cs
+++ b/tests/Avalonia.Base.UnitTests/AvaloniaPropertyTests.cs
@@ -83,7 +83,7 @@ namespace Avalonia.Base.UnitTests
             var target = new Class1();
             string value = null;
 
-            Class1.FooProperty.Changed.Subscribe(x => value = (string)x.NewValue);
+            Class1.FooProperty.Changed.Subscribe(x => value = x.NewValue.GetValueOrDefault());
             target.SetValue(Class1.FooProperty, "newvalue");
 
             Assert.Equal("newvalue", value);
@@ -95,7 +95,7 @@ namespace Avalonia.Base.UnitTests
             var target = new Class1();
             var result = new List<string>();
 
-            Class1.FooProperty.Changed.Subscribe(x => result.Add((string)x.NewValue));
+            Class1.FooProperty.Changed.Subscribe(x => result.Add(x.NewValue.GetValueOrDefault()));
             target.SetValue(Class1.FooProperty, "animated", BindingPriority.Animation);
             target.SetValue(Class1.FooProperty, "local");
 
diff --git a/tests/Avalonia.Controls.UnitTests/Primitives/PopupTests.cs b/tests/Avalonia.Controls.UnitTests/Primitives/PopupTests.cs
index d9176ca55d..53a8db2176 100644
--- a/tests/Avalonia.Controls.UnitTests/Primitives/PopupTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/Primitives/PopupTests.cs
@@ -395,6 +395,53 @@ namespace Avalonia.Controls.UnitTests.Primitives
             }
         }
 
+        [Fact]
+        public void Focusable_Controls_In_Popup_Should_Get_Focus()
+        {
+            using (CreateServicesWithFocus())
+            {
+                var window = PreparedWindow();
+
+                var tb = new TextBox();
+                var b = new Button();
+                var p = new Popup
+                {
+                    PlacementTarget = window,
+                    Child = new StackPanel
+                    {
+                        Children =
+                        {
+                            tb,
+                            b
+                        }
+                    }
+                };
+                ((ISetLogicalParent)p).SetParent(p.PlacementTarget);
+                window.Show();
+
+                p.Open();
+
+                if(p.Host is OverlayPopupHost host)
+                {
+                    //Need to measure/arrange for visual children to show up
+                    //in OverlayPopupHost
+                    host.Measure(Size.Infinity);
+                    host.Arrange(new Rect(host.DesiredSize));
+                }
+
+                tb.Focus();
+
+                Assert.True(FocusManager.Instance?.Current == tb);
+
+                //Ensure focus remains in the popup
+                var nextFocus = KeyboardNavigationHandler.GetNext(FocusManager.Instance.Current, NavigationDirection.Next);
+
+                Assert.True(nextFocus == b);
+
+                p.Close();
+            }
+        }
+
         private IDisposable CreateServices()
         {
             return UnitTestApplication.Start(TestServices.StyledWindow.With(windowingPlatform:
@@ -407,6 +454,21 @@ namespace Avalonia.Controls.UnitTests.Primitives
                     })));
         }
 
+        private IDisposable CreateServicesWithFocus()
+        {
+            return UnitTestApplication.Start(TestServices.StyledWindow.With(windowingPlatform:
+                new MockWindowingPlatform(null,
+                    x =>
+                    {
+                        if (UsePopupHost)
+                            return null;
+                        return MockWindowingPlatform.CreatePopupMock(x).Object;
+                    }), 
+                    focusManager: new FocusManager(),
+                    keyboardDevice: () => new KeyboardDevice()));
+        }
+
+       
         private PointerPressedEventArgs CreatePointerPressedEventArgs(Window source, Point p)
         {
             var pointer = new Pointer(Pointer.GetNextFreeId(), PointerType.Mouse, true);