Merge branch 'master' into release/0.9

src/Avalonia.Base/AvaloniaObjectExtensions.cs

@@ -192,9 +192,9 @@ namespace Avalonia
         {
             return observable.Subscribe(e =>
             {
-                if (e.Sender is TTarget)
+                if (e.Sender is TTarget target)
                 {
-                    action((TTarget)e.Sender, e);
+                    action(target, e);
                 }
             });
         }
@@ -207,6 +207,7 @@ namespace Avalonia
         /// <param name="observable">The property changed observable.</param>
         /// <param name="handler">Given a TTarget, returns the handler.</param>
         /// <returns>A disposable that can be used to terminate the subscription.</returns>
+        [Obsolete("Use overload taking Action<TTarget, AvaloniaPropertyChangedEventArgs>.")]
         public static IDisposable AddClassHandler<TTarget>(
             this IObservable<AvaloniaPropertyChangedEventArgs> observable,
             Func<TTarget, Action<AvaloniaPropertyChangedEventArgs>> handler)
@@ -238,9 +239,7 @@ namespace Avalonia
             Func<TTarget, Action<AvaloniaPropertyChangedEventArgs>> handler)
             where TTarget : class
         {
-            var target = e.Sender as TTarget;
-
-            if (target != null)
+            if (e.Sender is TTarget target)
             {
                 handler(target)(e);
             }

src/Avalonia.Controls.DataGrid/DataGrid.cs

@@ -723,29 +723,29 @@ namespace Avalonia.Controls
 
             PseudoClass<DataGrid, bool>(IsValidProperty, x => !x, ":invalid");
 
-            ItemsProperty.Changed.AddClassHandler<DataGrid>(x => x.OnItemsPropertyChanged);
-            CanUserResizeColumnsProperty.Changed.AddClassHandler<DataGrid>(x => x.OnCanUserResizeColumnsChanged);
-            ColumnWidthProperty.Changed.AddClassHandler<DataGrid>(x => x.OnColumnWidthChanged);
-            RowBackgroundProperty.Changed.AddClassHandler<DataGrid>(x => x.OnRowBackgroundChanged);
-            AlternatingRowBackgroundProperty.Changed.AddClassHandler<DataGrid>(x => x.OnRowBackgroundChanged);
-            FrozenColumnCountProperty.Changed.AddClassHandler<DataGrid>(x => x.OnFrozenColumnCountChanged);
-            GridLinesVisibilityProperty.Changed.AddClassHandler<DataGrid>(x => x.OnGridLinesVisibilityChanged);
-            HeadersVisibilityProperty.Changed.AddClassHandler<DataGrid>(x => x.OnHeadersVisibilityChanged);
-            HorizontalGridLinesBrushProperty.Changed.AddClassHandler<DataGrid>(x => x.OnHorizontalGridLinesBrushChanged);
-            IsReadOnlyProperty.Changed.AddClassHandler<DataGrid>(x => x.OnIsReadOnlyChanged);
-            MaxColumnWidthProperty.Changed.AddClassHandler<DataGrid>(x => x.OnMaxColumnWidthChanged);
-            MinColumnWidthProperty.Changed.AddClassHandler<DataGrid>(x => x.OnMinColumnWidthChanged);
-            RowHeightProperty.Changed.AddClassHandler<DataGrid>(x => x.OnRowHeightChanged);
-            RowHeaderWidthProperty.Changed.AddClassHandler<DataGrid>(x => x.OnRowHeaderWidthChanged);
-            SelectionModeProperty.Changed.AddClassHandler<DataGrid>(x => x.OnSelectionModeChanged);
-            VerticalGridLinesBrushProperty.Changed.AddClassHandler<DataGrid>(x => x.OnVerticalGridLinesBrushChanged);
-            SelectedIndexProperty.Changed.AddClassHandler<DataGrid>(x => x.OnSelectedIndexChanged);
-            SelectedItemProperty.Changed.AddClassHandler<DataGrid>(x => x.OnSelectedItemChanged);
-            IsEnabledProperty.Changed.AddClassHandler<DataGrid>(x => x.DataGrid_IsEnabledChanged);
-            AreRowGroupHeadersFrozenProperty.Changed.AddClassHandler<DataGrid>(x => x.OnAreRowGroupHeadersFrozenChanged);
-            RowDetailsTemplateProperty.Changed.AddClassHandler<DataGrid>(x => x.OnRowDetailsTemplateChanged);
-            RowDetailsVisibilityModeProperty.Changed.AddClassHandler<DataGrid>(x => x.OnRowDetailsVisibilityModeChanged);
-            AutoGenerateColumnsProperty.Changed.AddClassHandler<DataGrid>(x => x.OnAutoGenerateColumnsChanged);
+            ItemsProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnItemsPropertyChanged(e));
+            CanUserResizeColumnsProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnCanUserResizeColumnsChanged(e));
+            ColumnWidthProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnColumnWidthChanged(e));
+            RowBackgroundProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnRowBackgroundChanged(e));
+            AlternatingRowBackgroundProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnRowBackgroundChanged(e));
+            FrozenColumnCountProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnFrozenColumnCountChanged(e));
+            GridLinesVisibilityProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnGridLinesVisibilityChanged(e));
+            HeadersVisibilityProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnHeadersVisibilityChanged(e));
+            HorizontalGridLinesBrushProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnHorizontalGridLinesBrushChanged(e));
+            IsReadOnlyProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnIsReadOnlyChanged(e));
+            MaxColumnWidthProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnMaxColumnWidthChanged(e));
+            MinColumnWidthProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnMinColumnWidthChanged(e));
+            RowHeightProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnRowHeightChanged(e));
+            RowHeaderWidthProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnRowHeaderWidthChanged(e));
+            SelectionModeProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnSelectionModeChanged(e));
+            VerticalGridLinesBrushProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnVerticalGridLinesBrushChanged(e));
+            SelectedIndexProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnSelectedIndexChanged(e));
+            SelectedItemProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnSelectedItemChanged(e));
+            IsEnabledProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.DataGrid_IsEnabledChanged(e));
+            AreRowGroupHeadersFrozenProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnAreRowGroupHeadersFrozenChanged(e));
+            RowDetailsTemplateProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnRowDetailsTemplateChanged(e));
+            RowDetailsVisibilityModeProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnRowDetailsVisibilityModeChanged(e));
+            AutoGenerateColumnsProperty.Changed.AddClassHandler<DataGrid>((x, e) => x.OnAutoGenerateColumnsChanged(e));
         }
 
         /// <summary>
@@ -3533,7 +3533,7 @@ namespace Avalonia.Controls
                 if (AreColumnHeadersVisible &&
                     _vScrollBar != null && _vScrollBar.IsVisible)
                 {
-                    _topRightCornerHeader.IsVisible = true; ;
+                    _topRightCornerHeader.IsVisible = true;
                 }
                 else
                 {
@@ -5594,7 +5594,7 @@ namespace Avalonia.Controls
                     {
                         // This will trigger a call to this method via Cells_SizeChanged for 
                         // which no processing is needed.
-                        _vScrollBar.IsVisible = true; ;
+                        _vScrollBar.IsVisible = true;
                         if (_vScrollBar.DesiredSize.Width == 0)
                         {
                             // We need to know the width for the rest of layout to work correctly so measure it now

src/Avalonia.Controls.DataGrid/DataGridCell.cs

@@ -29,7 +29,7 @@ namespace Avalonia.Controls
         static DataGridCell()
         {
             PointerPressedEvent.AddClassHandler<DataGridCell>(
-                x => x.DataGridCell_PointerPressed, handledEventsToo: true);
+                (x,e) => x.DataGridCell_PointerPressed(e), handledEventsToo: true);
         }
         public DataGridCell()
         { }
@@ -219,4 +219,4 @@ namespace Avalonia.Controls
             }
         }
     }
-}
+}

src/Avalonia.Controls.DataGrid/DataGridColumnHeader.cs

@@ -67,7 +67,7 @@ namespace Avalonia.Controls
 
         static DataGridColumnHeader()
         {
-            AreSeparatorsVisibleProperty.Changed.AddClassHandler<DataGridColumnHeader>(x => x.OnAreSeparatorsVisibleChanged);
+            AreSeparatorsVisibleProperty.Changed.AddClassHandler<DataGridColumnHeader>((x,e) => x.OnAreSeparatorsVisibleChanged(e));
         }
 
         /// <summary>

src/Avalonia.Controls.DataGrid/DataGridRow.cs

@@ -116,10 +116,10 @@ namespace Avalonia.Controls
 
         static DataGridRow()
         {
-            HeaderProperty.Changed.AddClassHandler<DataGridRow>(x => x.OnHeaderChanged);
-            DetailsTemplateProperty.Changed.AddClassHandler<DataGridRow>(x => x.OnDetailsTemplateChanged);
-            AreDetailsVisibleProperty.Changed.AddClassHandler<DataGridRow>(x => x.OnAreDetailsVisibleChanged);
-            PointerPressedEvent.AddClassHandler<DataGridRow>(x => x.DataGridRow_PointerPressed, handledEventsToo: true);
+            HeaderProperty.Changed.AddClassHandler<DataGridRow>((x, e) => x.OnHeaderChanged(e));
+            DetailsTemplateProperty.Changed.AddClassHandler<DataGridRow>((x, e) => x.OnDetailsTemplateChanged(e));
+            AreDetailsVisibleProperty.Changed.AddClassHandler<DataGridRow>((x, e) => x.OnAreDetailsVisibleChanged(e));
+            PointerPressedEvent.AddClassHandler<DataGridRow>((x, e) => x.DataGridRow_PointerPressed(e), handledEventsToo: true);
         }
 
         /// <summary>

src/Avalonia.Controls.DataGrid/DataGridRowGroupHeader.cs

@@ -109,7 +109,7 @@ namespace Avalonia.Controls
 
         static DataGridRowGroupHeader()
         {
-            SublevelIndentProperty.Changed.AddClassHandler<DataGridRowGroupHeader>(x => x.OnSublevelIndentChanged);
+            SublevelIndentProperty.Changed.AddClassHandler<DataGridRowGroupHeader>((x,e) => x.OnSublevelIndentChanged(e));
         }
 
         /// <summary>
@@ -446,4 +446,4 @@ namespace Avalonia.Controls
         }
 
     }
-}
+}

src/Avalonia.Controls/AutoCompleteBox.cs

@@ -805,15 +805,15 @@ namespace Avalonia.Controls
         {
             FocusableProperty.OverrideDefaultValue<AutoCompleteBox>(true);
 
-            MinimumPopulateDelayProperty.Changed.AddClassHandler<AutoCompleteBox>(x => x.OnMinimumPopulateDelayChanged);
-            IsDropDownOpenProperty.Changed.AddClassHandler<AutoCompleteBox>(x => x.OnIsDropDownOpenChanged);
-            SelectedItemProperty.Changed.AddClassHandler<AutoCompleteBox>(x => x.OnSelectedItemPropertyChanged);
-            TextProperty.Changed.AddClassHandler<AutoCompleteBox>(x => x.OnTextPropertyChanged);
-            SearchTextProperty.Changed.AddClassHandler<AutoCompleteBox>(x => x.OnSearchTextPropertyChanged);
-            FilterModeProperty.Changed.AddClassHandler<AutoCompleteBox>(x => x.OnFilterModePropertyChanged);
-            ItemFilterProperty.Changed.AddClassHandler<AutoCompleteBox>(x => x.OnItemFilterPropertyChanged);
-            ItemsProperty.Changed.AddClassHandler<AutoCompleteBox>(x => x.OnItemsPropertyChanged);
-            IsEnabledProperty.Changed.AddClassHandler<AutoCompleteBox>(x => x.OnControlIsEnabledChanged);
+            MinimumPopulateDelayProperty.Changed.AddClassHandler<AutoCompleteBox>((x,e) => x.OnMinimumPopulateDelayChanged(e));
+            IsDropDownOpenProperty.Changed.AddClassHandler<AutoCompleteBox>((x,e) => x.OnIsDropDownOpenChanged(e));
+            SelectedItemProperty.Changed.AddClassHandler<AutoCompleteBox>((x,e) => x.OnSelectedItemPropertyChanged(e));
+            TextProperty.Changed.AddClassHandler<AutoCompleteBox>((x,e) => x.OnTextPropertyChanged(e));
+            SearchTextProperty.Changed.AddClassHandler<AutoCompleteBox>((x,e) => x.OnSearchTextPropertyChanged(e));
+            FilterModeProperty.Changed.AddClassHandler<AutoCompleteBox>((x,e) => x.OnFilterModePropertyChanged(e));
+            ItemFilterProperty.Changed.AddClassHandler<AutoCompleteBox>((x,e) => x.OnItemFilterPropertyChanged(e));
+            ItemsProperty.Changed.AddClassHandler<AutoCompleteBox>((x,e) => x.OnItemsPropertyChanged(e));
+            IsEnabledProperty.Changed.AddClassHandler<AutoCompleteBox>((x,e) => x.OnControlIsEnabledChanged(e));
         }
 
         /// <summary>

src/Avalonia.Controls/Calendar/Calendar.cs

@@ -2057,18 +2057,17 @@ namespace Avalonia.Controls
 
         static Calendar()
         {
-            IsEnabledProperty.Changed.AddClassHandler<Calendar>(x => x.OnIsEnabledChanged);
-            FirstDayOfWeekProperty.Changed.AddClassHandler<Calendar>(x => x.OnFirstDayOfWeekChanged);
-            IsTodayHighlightedProperty.Changed.AddClassHandler<Calendar>(x => x.OnIsTodayHighlightedChanged);
-            DisplayModeProperty.Changed.AddClassHandler<Calendar>(x => x.OnDisplayModePropertyChanged);
-            SelectionModeProperty.Changed.AddClassHandler<Calendar>(x => x.OnSelectionModeChanged);
-            SelectedDateProperty.Changed.AddClassHandler<Calendar>(x => x.OnSelectedDateChanged);
-            DisplayDateProperty.Changed.AddClassHandler<Calendar>(x => x.OnDisplayDateChanged);
-            DisplayDateStartProperty.Changed.AddClassHandler<Calendar>(x => x.OnDisplayDateStartChanged);
-            DisplayDateEndProperty.Changed.AddClassHandler<Calendar>(x => x.OnDisplayDateEndChanged);
-            KeyDownEvent.AddClassHandler<Calendar>(x => x.Calendar_KeyDown);
-            KeyUpEvent.AddClassHandler<Calendar>(x => x.Calendar_KeyUp);
-            
+            IsEnabledProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnIsEnabledChanged(e));
+            FirstDayOfWeekProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnFirstDayOfWeekChanged(e));
+            IsTodayHighlightedProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnIsTodayHighlightedChanged(e));
+            DisplayModeProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnDisplayModePropertyChanged(e));
+            SelectionModeProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnSelectionModeChanged(e));
+            SelectedDateProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnSelectedDateChanged(e));
+            DisplayDateProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnDisplayDateChanged(e));
+            DisplayDateStartProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnDisplayDateStartChanged(e));
+            DisplayDateEndProperty.Changed.AddClassHandler<Calendar>((x,e) => x.OnDisplayDateEndChanged(e));
+            KeyDownEvent.AddClassHandler<Calendar>((x,e) => x.Calendar_KeyDown(e));
+            KeyUpEvent.AddClassHandler<Calendar>((x,e) => x.Calendar_KeyUp(e));
         }
 
         /// <summary>

src/Avalonia.Controls/Calendar/DatePicker.cs

@@ -393,14 +393,14 @@ namespace Avalonia.Controls
         {
             FocusableProperty.OverrideDefaultValue<DatePicker>(true);
 
-            DisplayDateProperty.Changed.AddClassHandler<DatePicker>(x => x.OnDisplayDateChanged);
-            DisplayDateStartProperty.Changed.AddClassHandler<DatePicker>(x => x.OnDisplayDateStartChanged);
-            DisplayDateEndProperty.Changed.AddClassHandler<DatePicker>(x => x.OnDisplayDateEndChanged);
-            IsDropDownOpenProperty.Changed.AddClassHandler<DatePicker>(x => x.OnIsDropDownOpenChanged);
-            SelectedDateProperty.Changed.AddClassHandler<DatePicker>(x => x.OnSelectedDateChanged);
-            SelectedDateFormatProperty.Changed.AddClassHandler<DatePicker>(x => x.OnSelectedDateFormatChanged);
-            CustomDateFormatStringProperty.Changed.AddClassHandler<DatePicker>(x => x.OnCustomDateFormatStringChanged);
-            TextProperty.Changed.AddClassHandler<DatePicker>(x => x.OnTextChanged);
+            DisplayDateProperty.Changed.AddClassHandler<DatePicker>((x,e) => x.OnDisplayDateChanged(e));
+            DisplayDateStartProperty.Changed.AddClassHandler<DatePicker>((x,e) => x.OnDisplayDateStartChanged(e));
+            DisplayDateEndProperty.Changed.AddClassHandler<DatePicker>((x,e) => x.OnDisplayDateEndChanged(e));
+            IsDropDownOpenProperty.Changed.AddClassHandler<DatePicker>((x,e) => x.OnIsDropDownOpenChanged(e));
+            SelectedDateProperty.Changed.AddClassHandler<DatePicker>((x,e) => x.OnSelectedDateChanged(e));
+            SelectedDateFormatProperty.Changed.AddClassHandler<DatePicker>((x,e) => x.OnSelectedDateFormatChanged(e));
+            CustomDateFormatStringProperty.Changed.AddClassHandler<DatePicker>((x,e) => x.OnCustomDateFormatStringChanged(e));
+            TextProperty.Changed.AddClassHandler<DatePicker>((x,e) => x.OnTextChanged(e));
         }
         /// <summary>
         /// Initializes a new instance of the

src/Avalonia.Controls/Carousel.cs

@@ -84,17 +84,5 @@ namespace Avalonia.Controls
                 --SelectedIndex;
             }
         }
-
-        /// <inheritdoc/>
-        protected override void OnKeyDown(KeyEventArgs e)
-        {
-            // Ignore key presses.
-        }
-
-        /// <inheritdoc/>
-        protected override void OnPointerPressed(PointerPressedEventArgs e)
-        {
-            // Ignore pointer presses.
-        }
     }
 }

src/Avalonia.Controls/ComboBox.cs

@@ -65,8 +65,8 @@ namespace Avalonia.Controls
         {
             ItemsPanelProperty.OverrideDefaultValue<ComboBox>(DefaultPanel);
             FocusableProperty.OverrideDefaultValue<ComboBox>(true);
-            SelectedItemProperty.Changed.AddClassHandler<ComboBox>(x => x.SelectedItemChanged);
-            KeyDownEvent.AddClassHandler<ComboBox>(x => x.OnKeyDown, Interactivity.RoutingStrategies.Tunnel);
+            SelectedItemProperty.Changed.AddClassHandler<ComboBox>((x,e) => x.SelectedItemChanged(e));
+            KeyDownEvent.AddClassHandler<ComboBox>((x, e) => x.OnKeyDown(e), Interactivity.RoutingStrategies.Tunnel);
         }
 
         /// <summary>

src/Avalonia.Controls/ContentControl.cs

@@ -43,7 +43,7 @@ namespace Avalonia.Controls
 
         static ContentControl()
         {
-            ContentProperty.Changed.AddClassHandler<ContentControl>(x => x.ContentChanged);
+            ContentProperty.Changed.AddClassHandler<ContentControl>((x, e) => x.ContentChanged(e));
         }
 
         /// <summary>

src/Avalonia.Controls/DataValidationErrors.cs

@@ -56,7 +56,7 @@ namespace Avalonia.Controls
         {
             ErrorsProperty.Changed.Subscribe(ErrorsChanged);
             HasErrorsProperty.Changed.Subscribe(HasErrorsChanged);
-            TemplatedParentProperty.Changed.AddClassHandler<DataValidationErrors>(x => x.OnTemplatedParentChange);
+            TemplatedParentProperty.Changed.AddClassHandler<DataValidationErrors>((x, e) => x.OnTemplatedParentChange(e));
         }
 
         private void OnTemplatedParentChange(AvaloniaPropertyChangedEventArgs e)

src/Avalonia.Controls/Decorator.cs

@@ -29,7 +29,7 @@ namespace Avalonia.Controls
         static Decorator()
         {
             AffectsMeasure<Decorator>(ChildProperty, PaddingProperty);
-            ChildProperty.Changed.AddClassHandler<Decorator>(x => x.ChildChanged);
+            ChildProperty.Changed.AddClassHandler<Decorator>((x, e) => x.ChildChanged(e));
         }
 
         /// <summary>

src/Avalonia.Controls/Expander.cs

@@ -37,7 +37,7 @@ namespace Avalonia.Controls
 
             PseudoClass<Expander>(IsExpandedProperty, ":expanded");
 
-            IsExpandedProperty.Changed.AddClassHandler<Expander>(x => x.OnIsExpandedChanged);
+            IsExpandedProperty.Changed.AddClassHandler<Expander>((x, e) => x.OnIsExpandedChanged(e));
         }
 
         public IPageTransition ContentTransition

src/Avalonia.Controls/ItemsControl.cs

@@ -64,8 +64,8 @@ namespace Avalonia.Controls
         /// </summary>
         static ItemsControl()
         {
-            ItemsProperty.Changed.AddClassHandler<ItemsControl>(x => x.ItemsChanged);
-            ItemTemplateProperty.Changed.AddClassHandler<ItemsControl>(x => x.ItemTemplateChanged);
+            ItemsProperty.Changed.AddClassHandler<ItemsControl>((x, e) => x.ItemsChanged(e));
+            ItemTemplateProperty.Changed.AddClassHandler<ItemsControl>((x, e) => x.ItemTemplateChanged(e));
         }
 
         /// <summary>

src/Avalonia.Controls/LayoutTransformControl.cs

@@ -28,11 +28,13 @@ namespace Avalonia.Controls
             ClipToBoundsProperty.OverrideDefaultValue<LayoutTransformControl>(true);
 
             LayoutTransformProperty.Changed
-                .AddClassHandler<LayoutTransformControl>(x => x.OnLayoutTransformChanged);
+                .AddClassHandler<LayoutTransformControl>((x, e) => x.OnLayoutTransformChanged(e));
 
             ChildProperty.Changed
-                .AddClassHandler<LayoutTransformControl>(x => x.OnChildChanged);
-            UseRenderTransformProperty.Changed.AddClassHandler<LayoutTransformControl>(x => x.OnUseRenderTransformPropertyChanged);
+                .AddClassHandler<LayoutTransformControl>((x, e) => x.OnChildChanged(e));
+
+            UseRenderTransformProperty.Changed
+                .AddClassHandler<LayoutTransformControl>((x, e) => x.OnUseRenderTransformPropertyChanged(e));
         }
 
         /// <summary>

src/Avalonia.Controls/MenuBase.cs

@@ -64,7 +64,7 @@ namespace Avalonia.Controls
         /// </summary>
         static MenuBase()
         {
-            MenuItem.SubmenuOpenedEvent.AddClassHandler<MenuBase>(x => x.OnSubmenuOpened);
+            MenuItem.SubmenuOpenedEvent.AddClassHandler<MenuBase>((x, e) => x.OnSubmenuOpened(e));
         }
 
         /// <summary>

src/Avalonia.Controls/MenuItem.cs

@@ -102,13 +102,13 @@ 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);
+            HeaderProperty.Changed.AddClassHandler<MenuItem>((x, e) => x.HeaderChanged(e));
+            IconProperty.Changed.AddClassHandler<MenuItem>((x, e) => x.IconChanged(e));
+            IsSelectedProperty.Changed.AddClassHandler<MenuItem>((x, e) => x.IsSelectedChanged(e));
             ItemsPanelProperty.OverrideDefaultValue<MenuItem>(DefaultPanel);
-            ClickEvent.AddClassHandler<MenuItem>(x => x.OnClick);
-            SubmenuOpenedEvent.AddClassHandler<MenuItem>(x => x.OnSubmenuOpened);
-            IsSubMenuOpenProperty.Changed.AddClassHandler<MenuItem>(x => x.SubMenuOpenChanged);
+            ClickEvent.AddClassHandler<MenuItem>((x, e) => x.OnClick(e));
+            SubmenuOpenedEvent.AddClassHandler<MenuItem>((x, e) => x.OnSubmenuOpened(e));
+            IsSubMenuOpenProperty.Changed.AddClassHandler<MenuItem>((x, e) => x.SubMenuOpenChanged(e));
         }
 
         public MenuItem()

src/Avalonia.Controls/Presenters/CarouselPresenter.cs

@@ -46,8 +46,8 @@ namespace Avalonia.Controls.Presenters
         /// </summary>
         static CarouselPresenter()
         {
-            IsVirtualizedProperty.Changed.AddClassHandler<CarouselPresenter>(x => x.IsVirtualizedChanged);
-            SelectedIndexProperty.Changed.AddClassHandler<CarouselPresenter>(x => x.SelectedIndexChanged);
+            IsVirtualizedProperty.Changed.AddClassHandler<CarouselPresenter>((x, e) => x.IsVirtualizedChanged(e));
+            SelectedIndexProperty.Changed.AddClassHandler<CarouselPresenter>((x, e) => x.SelectedIndexChanged(e));
         }
 
         /// <summary>

src/Avalonia.Controls/Presenters/ContentPresenter.cs

@@ -94,9 +94,9 @@ namespace Avalonia.Controls.Presenters
         {
             AffectsRender<ContentPresenter>(BackgroundProperty, BorderBrushProperty, BorderThicknessProperty, CornerRadiusProperty);
             AffectsMeasure<ContentPresenter>(BorderThicknessProperty, PaddingProperty);
-            ContentProperty.Changed.AddClassHandler<ContentPresenter>(x => x.ContentChanged);
-            ContentTemplateProperty.Changed.AddClassHandler<ContentPresenter>(x => x.ContentChanged);
-            TemplatedParentProperty.Changed.AddClassHandler<ContentPresenter>(x => x.TemplatedParentChanged);
+            ContentProperty.Changed.AddClassHandler<ContentPresenter>((x, e) => x.ContentChanged(e));
+            ContentTemplateProperty.Changed.AddClassHandler<ContentPresenter>((x, e) => x.ContentChanged(e));
+            TemplatedParentProperty.Changed.AddClassHandler<ContentPresenter>((x, e) => x.TemplatedParentChanged(e));
         }
 
         /// <summary>

src/Avalonia.Controls/Presenters/ItemsPresenter.cs

@@ -35,7 +35,7 @@ namespace Avalonia.Controls.Presenters
                 KeyboardNavigationMode.Once);
 
             VirtualizationModeProperty.Changed
-                .AddClassHandler<ItemsPresenter>(x => x.VirtualizationModeChanged);
+                .AddClassHandler<ItemsPresenter>((x, e) => x.VirtualizationModeChanged(e));
         }
 
         /// <summary>

src/Avalonia.Controls/Presenters/ItemsPresenterBase.cs

@@ -45,7 +45,7 @@ namespace Avalonia.Controls.Presenters
         /// </summary>
         static ItemsPresenterBase()
         {
-            TemplatedParentProperty.Changed.AddClassHandler<ItemsPresenterBase>(x => x.TemplatedParentChanged);
+            TemplatedParentProperty.Changed.AddClassHandler<ItemsPresenterBase>((x,e) => x.TemplatedParentChanged(e));
         }
 
         /// <summary>

src/Avalonia.Controls/Presenters/ScrollContentPresenter.cs

@@ -73,7 +73,7 @@ namespace Avalonia.Controls.Presenters
         static ScrollContentPresenter()
         {
             ClipToBoundsProperty.OverrideDefaultValue(typeof(ScrollContentPresenter), true);
-            ChildProperty.Changed.AddClassHandler<ScrollContentPresenter>(x => x.ChildChanged);
+            ChildProperty.Changed.AddClassHandler<ScrollContentPresenter>((x, e) => x.ChildChanged(e));
             AffectsArrange<ScrollContentPresenter>(OffsetProperty);
         }
 
@@ -246,7 +246,7 @@ namespace Avalonia.Controls.Presenters
                 if (isLogical)
                     _activeLogicalGestureScrolls?.TryGetValue(e.Id, out delta);
                 delta += e.Delta;
-                
+
                 if (Extent.Height > Viewport.Height)
                 {
                     double dy;
@@ -293,7 +293,7 @@ namespace Avalonia.Controls.Presenters
             }
         }
 
-        private void OnScrollGestureEnded(object sender, ScrollGestureEndedEventArgs e) 
+        private void OnScrollGestureEnded(object sender, ScrollGestureEndedEventArgs e)
             => _activeLogicalGestureScrolls?.Remove(e.Id);
 
         /// <inheritdoc/>

src/Avalonia.Controls/Primitives/HeaderedContentControl.cs

@@ -30,7 +30,7 @@ namespace Avalonia.Controls.Primitives
         /// </summary>
         static HeaderedContentControl()
         {
-            ContentProperty.Changed.AddClassHandler<HeaderedContentControl>(x => x.HeaderChanged);
+            ContentProperty.Changed.AddClassHandler<HeaderedContentControl>((x, e) => x.HeaderChanged(e));
         }
 
         /// <summary>

src/Avalonia.Controls/Primitives/HeaderedItemsControl.cs

@@ -24,7 +24,7 @@ namespace Avalonia.Controls.Primitives
         /// </summary>
         static HeaderedItemsControl()
         {
-            HeaderProperty.Changed.AddClassHandler<HeaderedItemsControl>(x => x.HeaderChanged);
+            HeaderProperty.Changed.AddClassHandler<HeaderedItemsControl>((x, e) => x.HeaderChanged(e));
         }
 
         /// <summary>

src/Avalonia.Controls/Primitives/HeaderedSelectingItemsControl.cs

@@ -24,7 +24,7 @@ namespace Avalonia.Controls.Primitives
         /// </summary>
         static HeaderedSelectingItemsControl()
         {
-            HeaderProperty.Changed.AddClassHandler<HeaderedSelectingItemsControl>(x => x.HeaderChanged);
+            HeaderProperty.Changed.AddClassHandler<HeaderedSelectingItemsControl>((x, e) => x.HeaderChanged(e));
         }
 
         /// <summary>

src/Avalonia.Controls/Primitives/Popup.cs

@@ -93,8 +93,8 @@ namespace Avalonia.Controls.Primitives
         static Popup()
         {
             IsHitTestVisibleProperty.OverrideDefaultValue<Popup>(false);
-            ChildProperty.Changed.AddClassHandler<Popup>(x => x.ChildChanged);
-            IsOpenProperty.Changed.AddClassHandler<Popup>(x => x.IsOpenChanged);
+            ChildProperty.Changed.AddClassHandler<Popup>((x, e) => x.ChildChanged(e));
+            IsOpenProperty.Changed.AddClassHandler<Popup>((x, e) => x.IsOpenChanged(e));
         }
 
         public Popup()

src/Avalonia.Controls/Primitives/PopupRoot.cs

@@ -17,7 +17,7 @@ namespace Avalonia.Controls.Primitives
     /// <summary>
     /// The root window of a <see cref="Popup"/>.
     /// </summary>
-    public class PopupRoot : WindowBase, IInteractive, IHostedVisualTreeRoot, IDisposable, IStyleHost, IPopupHost
+    public sealed class PopupRoot : WindowBase, IInteractive, IHostedVisualTreeRoot, IDisposable, IStyleHost, IPopupHost
     {
         private readonly TopLevel _parent;
         private PopupPositionerParameters _positionerParameters;

src/Avalonia.Controls/Primitives/ScrollBar.cs

@@ -58,8 +58,8 @@ namespace Avalonia.Controls.Primitives
             PseudoClass<ScrollBar, Orientation>(OrientationProperty, o => o == Orientation.Vertical, ":vertical");
             PseudoClass<ScrollBar, Orientation>(OrientationProperty, o => o == Orientation.Horizontal, ":horizontal");
 
-            Thumb.DragDeltaEvent.AddClassHandler<ScrollBar>(o => o.OnThumbDragDelta, RoutingStrategies.Bubble);
-            Thumb.DragCompletedEvent.AddClassHandler<ScrollBar>(o => o.OnThumbDragComplete, RoutingStrategies.Bubble);
+            Thumb.DragDeltaEvent.AddClassHandler<ScrollBar>((x, e) => x.OnThumbDragDelta(e), RoutingStrategies.Bubble);
+            Thumb.DragCompletedEvent.AddClassHandler<ScrollBar>((x, e) => x.OnThumbDragComplete(e), RoutingStrategies.Bubble);
         }
 
         /// <summary>

src/Avalonia.Controls/Primitives/SelectingItemsControl.cs

@@ -119,7 +119,7 @@ namespace Avalonia.Controls.Primitives
         /// </summary>
         static SelectingItemsControl()
         {
-            IsSelectedChangedEvent.AddClassHandler<SelectingItemsControl>(x => x.ContainerSelectionChanged);
+            IsSelectedChangedEvent.AddClassHandler<SelectingItemsControl>((x, e) => x.ContainerSelectionChanged(e));
         }
 
         /// <summary>
@@ -1088,8 +1088,8 @@ namespace Avalonia.Controls.Primitives
                 }
                 else
                 {
-                    SelectedIndex = _updateSelectedIndex != int.MinValue ? 
-                        _updateSelectedIndex : 
+                    SelectedIndex = _updateSelectedIndex != int.MinValue ?
+                        _updateSelectedIndex :
                         AlwaysSelected ? 0 : -1;
                 }
             }

src/Avalonia.Controls/Primitives/TemplatedControl.cs

@@ -99,7 +99,7 @@ namespace Avalonia.Controls.Primitives
         static TemplatedControl()
         {
             ClipToBoundsProperty.OverrideDefaultValue<TemplatedControl>(true);
-            TemplateProperty.Changed.AddClassHandler<TemplatedControl>(x => x.OnTemplateChanged);
+            TemplateProperty.Changed.AddClassHandler<TemplatedControl>((x, e) => x.OnTemplateChanged(e));
         }
 
         /// <summary>

src/Avalonia.Controls/Primitives/Thumb.cs

@@ -22,9 +22,9 @@ namespace Avalonia.Controls.Primitives
 
         static Thumb()
         {
-            DragStartedEvent.AddClassHandler<Thumb>(x => x.OnDragStarted, RoutingStrategies.Bubble);
-            DragDeltaEvent.AddClassHandler<Thumb>(x => x.OnDragDelta, RoutingStrategies.Bubble);
-            DragCompletedEvent.AddClassHandler<Thumb>(x => x.OnDragCompleted, RoutingStrategies.Bubble);
+            DragStartedEvent.AddClassHandler<Thumb>((x,e) => x.OnDragStarted(e), RoutingStrategies.Bubble);
+            DragDeltaEvent.AddClassHandler<Thumb>((x, e) => x.OnDragDelta(e), RoutingStrategies.Bubble);
+            DragCompletedEvent.AddClassHandler<Thumb>((x, e) => x.OnDragCompleted(e), RoutingStrategies.Bubble);
         }
 
         public event EventHandler<VectorEventArgs> DragStarted

src/Avalonia.Controls/Primitives/Track.cs

@@ -48,9 +48,9 @@ namespace Avalonia.Controls.Primitives
         {
             PseudoClass<Track, Orientation>(OrientationProperty, o => o == Orientation.Vertical, ":vertical");
             PseudoClass<Track, Orientation>(OrientationProperty, o => o == Orientation.Horizontal, ":horizontal");
-            ThumbProperty.Changed.AddClassHandler<Track>(x => x.ThumbChanged);
-            IncreaseButtonProperty.Changed.AddClassHandler<Track>(x => x.ButtonChanged);
-            DecreaseButtonProperty.Changed.AddClassHandler<Track>(x => x.ButtonChanged);
+            ThumbProperty.Changed.AddClassHandler<Track>((x,e) => x.ThumbChanged(e));
+            IncreaseButtonProperty.Changed.AddClassHandler<Track>((x, e) => x.ButtonChanged(e));
+            DecreaseButtonProperty.Changed.AddClassHandler<Track>((x, e) => x.ButtonChanged(e));
             AffectsArrange<Track>(MinimumProperty, MaximumProperty, ValueProperty, OrientationProperty);
         }
 

src/Avalonia.Controls/Primitives/UniformGrid.cs

@@ -28,6 +28,11 @@ namespace Avalonia.Controls.Primitives
         private int _rows;
         private int _columns;
 
+        static UniformGrid()
+        {
+            AffectsMeasure<UniformGrid>(RowsProperty, ColumnsProperty, FirstColumnProperty);
+        }
+
         /// <summary>
         /// Specifies the row count. If set to 0, row count will be calculated automatically.
         /// </summary>

src/Avalonia.Controls/ProgressBar.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 
+using System;
 using Avalonia.Controls.Primitives;
 using Avalonia.Layout;
 
@@ -38,8 +39,8 @@ namespace Avalonia.Controls
             PseudoClass<ProgressBar, Orientation>(OrientationProperty, o => o == Orientation.Horizontal, ":horizontal");
             PseudoClass<ProgressBar>(IsIndeterminateProperty, ":indeterminate");
 
-            ValueProperty.Changed.AddClassHandler<ProgressBar>(x => x.UpdateIndicatorWhenPropChanged);
-            IsIndeterminateProperty.Changed.AddClassHandler<ProgressBar>(x => x.UpdateIndicatorWhenPropChanged);
+            ValueProperty.Changed.AddClassHandler<ProgressBar>((x, e) => x.UpdateIndicatorWhenPropChanged(e));
+            IsIndeterminateProperty.Changed.AddClassHandler<ProgressBar>((x, e) => x.UpdateIndicatorWhenPropChanged(e));
         }
 
         public bool IsIndeterminate

src/Avalonia.Controls/ScrollViewer.cs

@@ -163,8 +163,8 @@ namespace Avalonia.Controls
         {
             AffectsValidation(ExtentProperty, OffsetProperty);
             AffectsValidation(ViewportProperty, OffsetProperty);
-            HorizontalScrollBarVisibilityProperty.Changed.AddClassHandler<ScrollViewer>(x => x.ScrollBarVisibilityChanged);
-            VerticalScrollBarVisibilityProperty.Changed.AddClassHandler<ScrollViewer>(x => x.ScrollBarVisibilityChanged);
+            HorizontalScrollBarVisibilityProperty.Changed.AddClassHandler<ScrollViewer>((x, e) => x.ScrollBarVisibilityChanged(e));
+            VerticalScrollBarVisibilityProperty.Changed.AddClassHandler<ScrollViewer>((x, e) => x.ScrollBarVisibilityChanged(e));
         }
 
         /// <summary>

src/Avalonia.Controls/Slider.cs

@@ -45,9 +45,9 @@ namespace Avalonia.Controls
             OrientationProperty.OverrideDefaultValue(typeof(Slider), Orientation.Horizontal);
             PseudoClass<Slider, Orientation>(OrientationProperty, o => o == Orientation.Vertical, ":vertical");
             PseudoClass<Slider, Orientation>(OrientationProperty, o => o == Orientation.Horizontal, ":horizontal");
-            Thumb.DragStartedEvent.AddClassHandler<Slider>(x => x.OnThumbDragStarted, RoutingStrategies.Bubble);
-            Thumb.DragDeltaEvent.AddClassHandler<Slider>(x => x.OnThumbDragDelta, RoutingStrategies.Bubble);
-            Thumb.DragCompletedEvent.AddClassHandler<Slider>(x => x.OnThumbDragCompleted, RoutingStrategies.Bubble);
+            Thumb.DragStartedEvent.AddClassHandler<Slider>((x, e) => x.OnThumbDragStarted(e), RoutingStrategies.Bubble);
+            Thumb.DragDeltaEvent.AddClassHandler<Slider>((x, e) => x.OnThumbDragDelta(e), RoutingStrategies.Bubble);
+            Thumb.DragCompletedEvent.AddClassHandler<Slider>((x, e) => x.OnThumbDragCompleted(e), RoutingStrategies.Bubble);
         }
 
         /// <summary>

src/Avalonia.Controls/TabItem.cs

@@ -30,8 +30,8 @@ namespace Avalonia.Controls
         {
             SelectableMixin.Attach<TabItem>(IsSelectedProperty);
             FocusableProperty.OverrideDefaultValue(typeof(TabItem), true);
-            IsSelectedProperty.Changed.AddClassHandler<TabItem>(x => x.UpdateSelectedContent);
-            DataContextProperty.Changed.AddClassHandler<TabItem>(x => x.UpdateHeader);
+            IsSelectedProperty.Changed.AddClassHandler<TabItem>((x, e) => x.UpdateSelectedContent(e));
+            DataContextProperty.Changed.AddClassHandler<TabItem>((x, e) => x.UpdateHeader(e));
         }
 
         /// <summary>

src/Avalonia.Controls/TopLevel.cs

@@ -271,7 +271,7 @@ namespace Avalonia.Controls
         {
             (this as IInputRoot).MouseDevice?.TopLevelClosed(this);
             PlatformImpl = null;
-            Closed?.Invoke(this, EventArgs.Empty);
+            OnClosed(EventArgs.Empty);
             Renderer?.Dispose();
             Renderer = null;
         }
@@ -317,6 +317,12 @@ namespace Avalonia.Controls
         /// <param name="e">The event args.</param>
         protected virtual void OnOpened(EventArgs e) => Opened?.Invoke(this, e);
 
+        /// <summary>
+        /// Raises the <see cref="Closed"/> event.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        protected virtual void OnClosed(EventArgs e) => Closed?.Invoke(this, e);
+
         /// <summary>
         /// Tries to get a service from an <see cref="IAvaloniaDependencyResolver"/>, logging a
         /// warning if not found.

src/Avalonia.Controls/TreeViewItem.cs

@@ -54,7 +54,7 @@ namespace Avalonia.Controls
             SelectableMixin.Attach<TreeViewItem>(IsSelectedProperty);
             FocusableProperty.OverrideDefaultValue<TreeViewItem>(true);
             ItemsPanelProperty.OverrideDefaultValue<TreeViewItem>(DefaultPanel);
-            RequestBringIntoViewEvent.AddClassHandler<TreeViewItem>(x => x.OnRequestBringIntoView);
+            RequestBringIntoViewEvent.AddClassHandler<TreeViewItem>((x, e) => x.OnRequestBringIntoView(e));
         }
 
         /// <summary>

src/Avalonia.Controls/Window.cs

@@ -557,7 +557,7 @@ namespace Avalonia.Controls
             return result;
         }
 
-        protected override void HandleClosed()
+        protected sealed override void HandleClosed()
         {
             RaiseEvent(new RoutedEventArgs(WindowClosedEvent));
 
@@ -565,7 +565,7 @@ namespace Avalonia.Controls
         }
 
         /// <inheritdoc/>
-        protected override void HandleResized(Size clientSize)
+        protected sealed override void HandleResized(Size clientSize)
         {
             if (!AutoSizing)
             {

src/Avalonia.Controls/WindowBase.cs

@@ -47,7 +47,7 @@ namespace Avalonia.Controls
         static WindowBase()
         {
             IsVisibleProperty.OverrideDefaultValue<WindowBase>(false);
-            IsVisibleProperty.Changed.AddClassHandler<WindowBase>(x => x.IsVisibleChanged);
+            IsVisibleProperty.Changed.AddClassHandler<WindowBase>((x,e) => x.IsVisibleChanged(e));
 
             
             TopmostProperty.Changed.AddClassHandler<WindowBase>((w, e) => w.PlatformImpl?.SetTopmost((bool)e.NewValue));

src/Avalonia.Input/InputElement.cs

@@ -169,18 +169,18 @@ namespace Avalonia.Input
         {
             IsEnabledProperty.Changed.Subscribe(IsEnabledChanged);
 
-            GotFocusEvent.AddClassHandler<InputElement>(x => x.OnGotFocus);
-            LostFocusEvent.AddClassHandler<InputElement>(x => x.OnLostFocus);
-            KeyDownEvent.AddClassHandler<InputElement>(x => x.OnKeyDown);
-            KeyUpEvent.AddClassHandler<InputElement>(x => x.OnKeyUp);
-            TextInputEvent.AddClassHandler<InputElement>(x => x.OnTextInput);
-            PointerEnterEvent.AddClassHandler<InputElement>(x => x.OnPointerEnterCore);
-            PointerLeaveEvent.AddClassHandler<InputElement>(x => x.OnPointerLeaveCore);
-            PointerMovedEvent.AddClassHandler<InputElement>(x => x.OnPointerMoved);
-            PointerPressedEvent.AddClassHandler<InputElement>(x => x.OnPointerPressed);
-            PointerReleasedEvent.AddClassHandler<InputElement>(x => x.OnPointerReleased);
-            PointerCaptureLostEvent.AddClassHandler<InputElement>(x => x.OnPointerCaptureLost);
-            PointerWheelChangedEvent.AddClassHandler<InputElement>(x => x.OnPointerWheelChanged);
+            GotFocusEvent.AddClassHandler<InputElement>((x, e) => x.OnGotFocus(e));
+            LostFocusEvent.AddClassHandler<InputElement>((x, e) => x.OnLostFocus(e));
+            KeyDownEvent.AddClassHandler<InputElement>((x, e) => x.OnKeyDown(e));
+            KeyUpEvent.AddClassHandler<InputElement>((x, e) => x.OnKeyUp(e));
+            TextInputEvent.AddClassHandler<InputElement>((x, e) => x.OnTextInput(e));
+            PointerEnterEvent.AddClassHandler<InputElement>((x, e) => x.OnPointerEnterCore(e));
+            PointerLeaveEvent.AddClassHandler<InputElement>((x, e) => x.OnPointerLeaveCore(e));
+            PointerMovedEvent.AddClassHandler<InputElement>((x, e) => x.OnPointerMoved(e));
+            PointerPressedEvent.AddClassHandler<InputElement>((x, e) => x.OnPointerPressed(e));
+            PointerReleasedEvent.AddClassHandler<InputElement>((x, e) => x.OnPointerReleased(e));
+            PointerCaptureLostEvent.AddClassHandler<InputElement>((x, e) => x.OnPointerCaptureLost(e));
+            PointerWheelChangedEvent.AddClassHandler<InputElement>((x, e) => x.OnPointerWheelChanged(e));
 
             PseudoClass<InputElement, bool>(IsEffectivelyEnabledProperty, x => !x, ":disabled");
             PseudoClass<InputElement>(IsFocusedProperty, ":focus");

src/Avalonia.Interactivity/RoutedEvent.cs

@@ -113,24 +113,38 @@ namespace Avalonia.Interactivity
             Contract.Requires<ArgumentNullException>(ownerType != null);
         }
 
+        [Obsolete("Use overload taking Action<TTarget, TEventArgs>.")]
         public IDisposable AddClassHandler<TTarget>(
             Func<TTarget, Action<TEventArgs>> handler,
             RoutingStrategies routes = RoutingStrategies.Direct | RoutingStrategies.Bubble,
             bool handledEventsToo = false)
-                where TTarget : class, IInteractive
+            where TTarget : class, IInteractive
         {
-            EventHandler<RoutedEventArgs> adapter = (sender, e) =>
+            void Adapter(object sender, RoutedEventArgs e)
             {
-                var target = sender as TTarget;
-                var args = e as TEventArgs;
-
-                if (target != null && args != null)
+                if (sender is TTarget target && e is TEventArgs args)
                 {
                     handler(target)(args);
                 }
-            };
+            }
+
+            return AddClassHandler(typeof(TTarget), Adapter, routes, handledEventsToo);
+        }
+
+        public IDisposable AddClassHandler<TTarget>(
+            Action<TTarget, TEventArgs> handler,
+            RoutingStrategies routes = RoutingStrategies.Direct | RoutingStrategies.Bubble,
+            bool handledEventsToo = false) where TTarget : class, IInteractive
+        {
+            void Adapter(object sender, RoutedEventArgs e)
+            {
+                if (sender is TTarget target && e is TEventArgs args)
+                {
+                    handler(target, args);
+                }
+            }
 
-            return AddClassHandler(typeof(TTarget), adapter, routes, handledEventsToo);
+            return AddClassHandler(typeof(TTarget), Adapter, routes, handledEventsToo);
         }
     }
 }

src/Avalonia.Styling/StyledElement.cs

@@ -73,7 +73,7 @@ namespace Avalonia
         /// </summary>
         static StyledElement()
         {
-            DataContextProperty.Changed.AddClassHandler<StyledElement>(x => x.OnDataContextChangedCore);
+            DataContextProperty.Changed.AddClassHandler<StyledElement>((x,e) => x.OnDataContextChangedCore(e));
         }
 
         /// <summary>

src/Avalonia.Visuals/CornerRadius.cs

@@ -8,7 +8,10 @@ using Avalonia.Utilities;
 
 namespace Avalonia
 {
-    public struct CornerRadius
+    /// <summary>
+    /// Represents the radii of a rectangle's corners.
+    /// </summary>
+    public readonly struct CornerRadius : IEquatable<CornerRadius>
     {
         static CornerRadius()
         {
@@ -33,22 +36,59 @@ namespace Avalonia
             BottomLeft = bottomLeft;
         }
 
+        /// <summary>
+        /// Radius of the top left corner.
+        /// </summary>
         public double TopLeft { get; }
+
+        /// <summary>
+        /// Radius of the top right corner.
+        /// </summary>
         public double TopRight { get; }
+
+        /// <summary>
+        /// Radius of the bottom right corner.
+        /// </summary>
         public double BottomRight { get; }
+
+        /// <summary>
+        /// Radius of the bottom left corner.
+        /// </summary>
         public double BottomLeft { get; }
+
+        /// <summary>
+        /// Gets a value indicating whether all corner radii are set to 0.
+        /// </summary>
         public bool IsEmpty => TopLeft.Equals(0) && IsUniform;
+
+        /// <summary>
+        /// Gets a value indicating whether all corner radii are equal.
+        /// </summary>
         public bool IsUniform => TopLeft.Equals(TopRight) && BottomLeft.Equals(BottomRight) && TopRight.Equals(BottomRight);
 
-        public override bool Equals(object obj)
+        /// <summary>
+        /// Returns a boolean indicating whether the corner radius is equal to the other given corner radius.
+        /// </summary>
+        /// <param name="other">The other corner radius to test equality against.</param>
+        /// <returns>True if this corner radius is equal to other; False otherwise.</returns>
+        public bool Equals(CornerRadius other)
         {
-            if (obj is CornerRadius)
-            {
-                return this == (CornerRadius)obj;
-            }
-            return false;
+            // ReSharper disable CompareOfFloatsByEqualityOperator
+            return TopLeft == other.TopLeft &&
+                   
+                   TopRight == other.TopRight &&
+                   BottomRight == other.BottomRight &&
+                   BottomLeft == other.BottomLeft;
+            // ReSharper restore CompareOfFloatsByEqualityOperator
         }
 
+        /// <summary>
+        /// Returns a boolean indicating whether the given Object is equal to this corner radius instance.
+        /// </summary>
+        /// <param name="obj">The Object to compare against.</param>
+        /// <returns>True if the Object is equal to this corner radius; False otherwise.</returns>
+        public override bool Equals(object obj) => obj is CornerRadius other && Equals(other);
+
         public override int GetHashCode()
         {
             return TopLeft.GetHashCode() ^ TopRight.GetHashCode() ^ BottomLeft.GetHashCode() ^ BottomRight.GetHashCode();
@@ -61,7 +101,9 @@ namespace Avalonia
 
         public static CornerRadius Parse(string s)
         {
-            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid Thickness"))
+            const string exceptionMessage = "Invalid CornerRadius.";
+
+            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage))
             {
                 if (tokenizer.TryReadDouble(out var a))
                 {
@@ -78,21 +120,18 @@ namespace Avalonia
                     return new CornerRadius(a);
                 }
 
-                throw new FormatException("Invalid CornerRadius.");
+                throw new FormatException(exceptionMessage);
             }
         }
 
-        public static bool operator ==(CornerRadius cr1, CornerRadius cr2)
+        public static bool operator ==(CornerRadius left, CornerRadius right)
         {
-            return cr1.TopLeft.Equals(cr2.TopLeft)
-                   && cr1.TopRight.Equals(cr2.TopRight)
-                   && cr1.BottomRight.Equals(cr2.BottomRight)
-                   && cr1.BottomLeft.Equals(cr2.BottomLeft);
+            return left.Equals(right);
         }
 
-        public static bool operator !=(CornerRadius cr1, CornerRadius cr2)
+        public static bool operator !=(CornerRadius left, CornerRadius right)
         {
-            return !(cr1 == cr2);
+            return !(left == right);
         }
     }
 }

src/Avalonia.Visuals/Matrix.cs

@@ -10,7 +10,7 @@ namespace Avalonia
     /// <summary>
     /// A 2x3 matrix.
     /// </summary>
-    public readonly struct Matrix
+    public readonly struct Matrix : IEquatable<Matrix>
     {
         private readonly double _m11;
         private readonly double _m12;
@@ -235,12 +235,14 @@ namespace Avalonia
         /// <returns>True if this matrix is equal to other; False otherwise.</returns>
         public bool Equals(Matrix other)
         {
+            // ReSharper disable CompareOfFloatsByEqualityOperator
             return _m11 == other.M11 &&
                    _m12 == other.M12 &&
                    _m21 == other.M21 &&
                    _m22 == other.M22 &&
                    _m31 == other.M31 &&
                    _m32 == other.M32;
+            // ReSharper restore CompareOfFloatsByEqualityOperator
         }
 
         /// <summary>
@@ -248,15 +250,7 @@ namespace Avalonia
         /// </summary>
         /// <param name="obj">The Object to compare against.</param>
         /// <returns>True if the Object is equal to this matrix; False otherwise.</returns>
-        public override bool Equals(object obj)
-        {
-            if (!(obj is Matrix))
-            {
-                return false;
-            }
-
-            return Equals((Matrix)obj);
-        }
+        public override bool Equals(object obj) => obj is Matrix other && Equals(other);
 
         /// <summary>
         /// Returns the hash code for this instance.
@@ -316,7 +310,7 @@ namespace Avalonia
         /// <returns>The <see cref="Matrix"/>.</returns>
         public static Matrix Parse(string s)
         {
-            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid Matrix"))
+            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid Matrix."))
             {
                 return new Matrix(
                     tokenizer.ReadDouble(),

src/Avalonia.Visuals/Media/Geometry.cs

@@ -22,7 +22,7 @@ namespace Avalonia.Media
 
         static Geometry()
         {
-            TransformProperty.Changed.AddClassHandler<Geometry>(x => x.TransformChanged);
+            TransformProperty.Changed.AddClassHandler<Geometry>((x,e) => x.TransformChanged(e));
         }
 
         /// <summary>

src/Avalonia.Visuals/Media/PixelPoint.cs

@@ -10,7 +10,7 @@ namespace Avalonia
     /// <summary>
     /// Represents a point in device pixels.
     /// </summary>
-    public readonly struct PixelPoint
+    public readonly struct PixelPoint : IEquatable<PixelPoint>
     {
         /// <summary>
         /// A point representing 0,0.
@@ -46,7 +46,7 @@ namespace Avalonia
         /// <returns>True if the points are equal; otherwise false.</returns>
         public static bool operator ==(PixelPoint left, PixelPoint right)
         {
-            return left.X == right.X && left.Y == right.Y;
+            return left.Equals(right);
         }
 
         /// <summary>
@@ -120,7 +120,7 @@ namespace Avalonia
         /// <returns>The <see cref="PixelPoint"/>.</returns>
         public static PixelPoint Parse(string s)
         {
-            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid PixelPoint"))
+            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid PixelPoint."))
             {
                 return new PixelPoint(
                     tokenizer.ReadInt32(),
@@ -128,6 +128,18 @@ namespace Avalonia
             }
         }
 
+        /// <summary>
+        /// Returns a boolean indicating whether the point is equal to the other given point.
+        /// </summary>
+        /// <param name="other">The other point to test equality against.</param>
+        /// <returns>True if this point is equal to other; False otherwise.</returns>
+        public bool Equals(PixelPoint other)
+        {
+            // ReSharper disable CompareOfFloatsByEqualityOperator
+            return X == other.X && Y == other.Y;
+            // ReSharper restore CompareOfFloatsByEqualityOperator
+        }
+
         /// <summary>
         /// Checks for equality between a point and an object.
         /// </summary>
@@ -135,15 +147,7 @@ namespace Avalonia
         /// <returns>
         /// True if <paramref name="obj"/> is a point that equals the current point.
         /// </returns>
-        public override bool Equals(object obj)
-        {
-            if (obj is PixelPoint other)
-            {
-                return this == other;
-            }
-
-            return false;
-        }
+        public override bool Equals(object obj) => obj is PixelPoint other && Equals(other);
 
         /// <summary>
         /// Returns a hash code for a <see cref="PixelPoint"/>.

src/Avalonia.Visuals/Media/PixelRect.cs

@@ -10,7 +10,7 @@ namespace Avalonia
     /// <summary>
     /// Represents a rectangle in device pixels.
     /// </summary>
-    public readonly struct PixelRect
+    public readonly struct PixelRect : IEquatable<PixelRect>
     {
         /// <summary>
         /// An empty rectangle.
@@ -148,7 +148,7 @@ namespace Avalonia
         /// <returns>True if the rects are equal; otherwise false.</returns>
         public static bool operator ==(PixelRect left, PixelRect right)
         {
-            return left.Position == right.Position && left.Size == right.Size;
+            return left.Equals(right);
         }
 
         /// <summary>
@@ -196,20 +196,22 @@ namespace Avalonia
                 rect.Height);
         }
 
+        /// <summary>
+        /// Returns a boolean indicating whether the rect is equal to the other given rect.
+        /// </summary>
+        /// <param name="other">The other rect to test equality against.</param>
+        /// <returns>True if this rect is equal to other; False otherwise.</returns>
+        public bool Equals(PixelRect other)
+        {
+            return Position == other.Position && Size == other.Size;
+        }
+
         /// <summary>
         /// Returns a boolean indicating whether the given object is equal to this rectangle.
         /// </summary>
         /// <param name="obj">The object to compare against.</param>
         /// <returns>True if the object is equal to this rectangle; false otherwise.</returns>
-        public override bool Equals(object obj)
-        {
-            if (obj is PixelRect other)
-            {
-                return this == other;
-            }
-
-            return false;
-        }
+        public override bool Equals(object obj) => obj is PixelRect other && Equals(other);
 
         /// <summary>
         /// Returns the hash code for this instance.
@@ -432,7 +434,7 @@ namespace Avalonia
         /// <returns>The parsed <see cref="PixelRect"/>.</returns>
         public static PixelRect Parse(string s)
         {
-            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid PixelRect"))
+            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid PixelRect."))
             {
                 return new PixelRect(
                     tokenizer.ReadInt32(),

src/Avalonia.Visuals/Media/PixelSize.cs

@@ -10,7 +10,7 @@ namespace Avalonia
     /// <summary>
     /// Represents a size in device pixels.
     /// </summary>
-    public readonly struct PixelSize
+    public readonly struct PixelSize : IEquatable<PixelSize>
     {
         /// <summary>
         /// A size representing zero
@@ -51,7 +51,7 @@ namespace Avalonia
         /// <returns>True if the sizes are equal; otherwise false.</returns>
         public static bool operator ==(PixelSize left, PixelSize right)
         {
-            return left.Width == right.Width && left.Height == right.Height;
+            return left.Equals(right);
         }
 
         /// <summary>
@@ -72,7 +72,7 @@ namespace Avalonia
         /// <returns>The <see cref="PixelSize"/>.</returns>
         public static PixelSize Parse(string s)
         {
-            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid PixelSize"))
+            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid PixelSize."))
             {
                 return new PixelSize(
                     tokenizer.ReadInt32(),
@@ -80,6 +80,16 @@ namespace Avalonia
             }
         }
 
+        /// <summary>
+        /// Returns a boolean indicating whether the size is equal to the other given size.
+        /// </summary>
+        /// <param name="other">The other size to test equality against.</param>
+        /// <returns>True if this size is equal to other; False otherwise.</returns>
+        public bool Equals(PixelSize other)
+        {
+            return Width == other.Width && Height == other.Height;
+        }
+
         /// <summary>
         /// Checks for equality between a size and an object.
         /// </summary>
@@ -87,15 +97,7 @@ namespace Avalonia
         /// <returns>
         /// True if <paramref name="obj"/> is a size that equals the current size.
         /// </returns>
-        public override bool Equals(object obj)
-        {
-            if (obj is PixelSize other)
-            {
-                return this == other;
-            }
-
-            return false;
-        }
+        public override bool Equals(object obj) => obj is PixelSize other && Equals(other);
 
         /// <summary>
         /// Returns a hash code for a <see cref="PixelSize"/>.

src/Avalonia.Visuals/Point.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 System;
 using System.Globalization;
 using Avalonia.Animation.Animators;
 using Avalonia.Utilities;
@@ -10,7 +11,7 @@ namespace Avalonia
     /// <summary>
     /// Defines a point.
     /// </summary>
-    public readonly struct Point
+    public readonly struct Point : IEquatable<Point>
     {
         static Point()
         {
@@ -75,7 +76,7 @@ namespace Avalonia
         /// <returns>True if the points are equal; otherwise false.</returns>
         public static bool operator ==(Point left, Point right)
         {
-            return left.X == right.X && left.Y == right.Y;
+            return left.Equals(right);
         }
 
         /// <summary>
@@ -177,7 +178,7 @@ namespace Avalonia
         /// <returns>The <see cref="Thickness"/>.</returns>
         public static Point Parse(string s)
         {
-            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid Point"))
+            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid Point."))
             {
                 return new Point(
                     tokenizer.ReadDouble(),
@@ -186,6 +187,19 @@ namespace Avalonia
             }
         }
 
+        /// <summary>
+        /// Returns a boolean indicating whether the point is equal to the other given point.
+        /// </summary>
+        /// <param name="other">The other point to test equality against.</param>
+        /// <returns>True if this point is equal to other; False otherwise.</returns>
+        public bool Equals(Point other)
+        {
+            // ReSharper disable CompareOfFloatsByEqualityOperator
+            return _x == other._x &&
+                   _y == other._y;
+            // ReSharper enable CompareOfFloatsByEqualityOperator
+        }
+
         /// <summary>
         /// Checks for equality between a point and an object.
         /// </summary>
@@ -193,16 +207,7 @@ namespace Avalonia
         /// <returns>
         /// True if <paramref name="obj"/> is a point that equals the current point.
         /// </returns>
-        public override bool Equals(object obj)
-        {
-            if (obj is Point)
-            {
-                var other = (Point)obj;
-                return X == other.X && Y == other.Y;
-            }
-
-            return false;
-        }
+        public override bool Equals(object obj) => obj is Point other && Equals(other);
 
         /// <summary>
         /// Returns a hash code for a <see cref="Point"/>.

src/Avalonia.Visuals/Rect.cs

@@ -11,7 +11,7 @@ namespace Avalonia
     /// <summary>
     /// Defines a rectangle.
     /// </summary>
-    public readonly struct Rect
+    public readonly struct Rect : IEquatable<Rect>
     {
         static Rect()
         {
@@ -164,7 +164,9 @@ namespace Avalonia
         /// <summary>
         /// Gets a value that indicates whether the rectangle is empty.
         /// </summary>
+        // ReSharper disable CompareOfFloatsByEqualityOperator
         public bool IsEmpty => _width == 0 && _height == 0;
+        // ReSharper restore CompareOfFloatsByEqualityOperator
 
         /// <summary>
         /// Checks for equality between two <see cref="Rect"/>s.
@@ -174,7 +176,7 @@ namespace Avalonia
         /// <returns>True if the rects are equal; otherwise false.</returns>
         public static bool operator ==(Rect left, Rect right)
         {
-            return left.Position == right.Position && left.Size == right.Size;
+            return left.Equals(right);
         }
 
         /// <summary>
@@ -297,21 +299,27 @@ namespace Avalonia
                 Size.Deflate(thickness));
         }
 
+        /// <summary>
+        /// Returns a boolean indicating whether the rect is equal to the other given rect.
+        /// </summary>
+        /// <param name="other">The other rect to test equality against.</param>
+        /// <returns>True if this rect is equal to other; False otherwise.</returns>
+        public bool Equals(Rect other)
+        {
+            // ReSharper disable CompareOfFloatsByEqualityOperator
+            return _x == other._x &&
+                   _y == other._y &&
+                   _width == other._width &&
+                   _height == other._height;
+            // ReSharper enable CompareOfFloatsByEqualityOperator
+        }
+
         /// <summary>
         /// Returns a boolean indicating whether the given object is equal to this rectangle.
         /// </summary>
         /// <param name="obj">The object to compare against.</param>
         /// <returns>True if the object is equal to this rectangle; false otherwise.</returns>
-        public override bool Equals(object obj)
-        {
-            if (obj is Rect)
-            {
-                var other = (Rect)obj;
-                return Position == other.Position && Size == other.Size;
-            }
-
-            return false;
-        }
+        public override bool Equals(object obj) => obj is Rect other && Equals(other);
 
         /// <summary>
         /// Returns the hash code for this instance.
@@ -422,10 +430,10 @@ namespace Avalonia
             }
             else
             {
-                var x1 = Math.Min(this.X, rect.X);
-                var x2 = Math.Max(this.Right, rect.Right);
-                var y1 = Math.Min(this.Y, rect.Y);
-                var y2 = Math.Max(this.Bottom, rect.Bottom);
+                var x1 = Math.Min(X, rect.X);
+                var x2 = Math.Max(Right, rect.Right);
+                var y1 = Math.Min(Y, rect.Y);
+                var y2 = Math.Max(Bottom, rect.Bottom);
 
                 return new Rect(new Point(x1, y1), new Point(x2, y2));
             }
@@ -493,7 +501,7 @@ namespace Avalonia
         /// <returns>The parsed <see cref="Rect"/>.</returns>
         public static Rect Parse(string s)
         {
-            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid Rect"))
+            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid Rect."))
             {
                 return new Rect(
                     tokenizer.ReadDouble(),

src/Avalonia.Visuals/RelativePoint.cs

@@ -107,10 +107,7 @@ namespace Avalonia
         /// </summary>
         /// <param name="obj">The other object.</param>
         /// <returns>True if the objects are equal, otherwise false.</returns>
-        public override bool Equals(object obj)
-        {
-            return (obj is RelativePoint) && Equals((RelativePoint)obj);
-        }
+        public override bool Equals(object obj) => obj is RelativePoint other && Equals(other);
 
         /// <summary>
         /// Checks if the <see cref="RelativePoint"/> equals another point.
@@ -130,10 +127,7 @@ namespace Avalonia
         {
             unchecked
             {
-                int hash = 17;
-                hash = (hash * 23) + Unit.GetHashCode();
-                hash = (hash * 23) + Point.GetHashCode();
-                return hash;
+                return (_point.GetHashCode() * 397) ^ (int)_unit;
             }
         }
 
@@ -156,7 +150,7 @@ namespace Avalonia
         /// <returns>The parsed <see cref="RelativePoint"/>.</returns>
         public static RelativePoint Parse(string s)
         {
-            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid RelativePoint"))
+            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid RelativePoint."))
             {
                 var x = tokenizer.ReadString();
                 var y = tokenizer.ReadString();

src/Avalonia.Visuals/RelativeRect.cs

@@ -116,10 +116,7 @@ namespace Avalonia
         /// </summary>
         /// <param name="obj">The other object.</param>
         /// <returns>True if the objects are equal, otherwise false.</returns>
-        public override bool Equals(object obj)
-        {
-            return (obj is RelativeRect) && Equals((RelativeRect)obj);
-        }
+        public override bool Equals(object obj) => obj is RelativeRect other && Equals(other);
 
         /// <summary>
         /// Checks if the <see cref="RelativeRect"/> equals another rectangle.
@@ -139,10 +136,7 @@ namespace Avalonia
         {
             unchecked
             {
-                int hash = 17;
-                hash = (hash * 23) + Unit.GetHashCode();
-                hash = (hash * 23) + Rect.GetHashCode();
-                return hash;
+                return ((int)Unit * 397) ^ Rect.GetHashCode();
             }
         }
 
@@ -161,7 +155,7 @@ namespace Avalonia
                     Rect.Width * size.Width,
                     Rect.Height * size.Height);
         }
-        
+
         /// <summary>
         /// Parses a <see cref="RelativeRect"/> string.
         /// </summary>
@@ -169,7 +163,7 @@ namespace Avalonia
         /// <returns>The parsed <see cref="RelativeRect"/>.</returns>
         public static RelativeRect Parse(string s)
         {
-            using (var tokenizer = new StringTokenizer(s, exceptionMessage: "Invalid RelativeRect"))
+            using (var tokenizer = new StringTokenizer(s, exceptionMessage: "Invalid RelativeRect."))
             {
                 var x = tokenizer.ReadString();
                 var y = tokenizer.ReadString();

src/Avalonia.Visuals/Size.cs

@@ -11,7 +11,7 @@ namespace Avalonia
     /// <summary>
     /// Defines a size.
     /// </summary>
-    public readonly struct Size
+    public readonly struct Size : IEquatable<Size>
     {
         static Size()
         {
@@ -72,7 +72,7 @@ namespace Avalonia
         /// <returns>True if the sizes are equal; otherwise false.</returns>
         public static bool operator ==(Size left, Size right)
         {
-            return left._width == right._width && left._height == right._height;
+            return left.Equals(right);
         }
 
         /// <summary>
@@ -158,7 +158,7 @@ namespace Avalonia
         /// <returns>The <see cref="Size"/>.</returns>
         public static Size Parse(string s)
         {
-            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid Size"))
+            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid Size."))
             {
                 return new Size(
                     tokenizer.ReadDouble(),
@@ -191,6 +191,19 @@ namespace Avalonia
                 Math.Max(0, _height - thickness.Top - thickness.Bottom));
         }
 
+        /// <summary>
+        /// Returns a boolean indicating whether the size is equal to the other given size.
+        /// </summary>
+        /// <param name="other">The other size to test equality against.</param>
+        /// <returns>True if this size is equal to other; False otherwise.</returns>
+        public bool Equals(Size other)
+        {
+            // ReSharper disable CompareOfFloatsByEqualityOperator
+            return _width == other._width &&
+                   _height == other._height;
+            // ReSharper enable CompareOfFloatsByEqualityOperator
+        }
+
         /// <summary>
         /// Checks for equality between a size and an object.
         /// </summary>
@@ -198,16 +211,7 @@ namespace Avalonia
         /// <returns>
         /// True if <paramref name="obj"/> is a size that equals the current size.
         /// </returns>
-        public override bool Equals(object obj)
-        {
-            if (obj is Size)
-            {
-                var other = (Size)obj;
-                return Width == other.Width && Height == other.Height;
-            }
-
-            return false;
-        }
+        public override bool Equals(object obj) => obj is Size other && Equals(other);
 
         /// <summary>
         /// Returns a hash code for a <see cref="Size"/>.

src/Avalonia.Visuals/Thickness.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Globalization;
-using Avalonia.Animation;
 using Avalonia.Animation.Animators;
 using Avalonia.Utilities;
 
@@ -12,7 +11,7 @@ namespace Avalonia
     /// <summary>
     /// Describes the thickness of a frame around a rectangle.
     /// </summary>
-    public readonly struct Thickness
+    public readonly struct Thickness : IEquatable<Thickness>
     {
         static Thickness()
         {
@@ -204,7 +203,9 @@ namespace Avalonia
         /// <returns>The <see cref="Thickness"/>.</returns>
         public static Thickness Parse(string s)
         {
-            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage: "Invalid Thickness"))
+            const string exceptionMessage = "Invalid Thickness.";
+
+            using (var tokenizer = new StringTokenizer(s, CultureInfo.InvariantCulture, exceptionMessage))
             {
                 if (tokenizer.TryReadDouble(out var a))
                 {
@@ -221,10 +222,25 @@ namespace Avalonia
                     return new Thickness(a);
                 }
 
-                throw new FormatException("Invalid Thickness.");
+                throw new FormatException(exceptionMessage);
             }
         }
 
+        /// <summary>
+        /// Returns a boolean indicating whether the thickness is equal to the other given point.
+        /// </summary>
+        /// <param name="other">The other thickness to test equality against.</param>
+        /// <returns>True if this thickness is equal to other; False otherwise.</returns>
+        public bool Equals(Thickness other)
+        {
+            // ReSharper disable CompareOfFloatsByEqualityOperator
+            return _left == other._left &&
+                   _top == other._top &&
+                   _right == other._right &&
+                   _bottom == other._bottom;
+            // ReSharper restore CompareOfFloatsByEqualityOperator
+        }
+
         /// <summary>
         /// Checks for equality between a thickness and an object.
         /// </summary>
@@ -232,19 +248,7 @@ namespace Avalonia
         /// <returns>
         /// True if <paramref name="obj"/> is a size that equals the current size.
         /// </returns>
-        public override bool Equals(object obj)
-        {
-            if (obj is Thickness)
-            {
-                Thickness other = (Thickness)obj;
-                return Left == other.Left &&
-                       Top == other.Top &&
-                       Right == other.Right &&
-                       Bottom == other.Bottom;
-            }
-
-            return false;
-        }
+        public override bool Equals(object obj) => obj is Thickness other && Equals(other);
 
         /// <summary>
         /// Returns a hash code for a <see cref="Thickness"/>.

src/Avalonia.Visuals/Vector.cs

@@ -11,7 +11,7 @@ namespace Avalonia
     /// <summary>
     /// Defines a vector.
     /// </summary>
-    public readonly struct Vector
+    public readonly struct Vector : IEquatable<Vector>
     {
         static Vector()
         {
@@ -138,7 +138,6 @@ namespace Avalonia
         /// </summary>
         /// <param name="other">The other vector.</param>
         /// <returns>True if vectors are nearly equal.</returns>
-        [Pure]
         public bool NearlyEquals(Vector other)
         {
             const float tolerance = float.Epsilon;
@@ -146,13 +145,7 @@ namespace Avalonia
             return Math.Abs(_x - other._x) < tolerance && Math.Abs(_y - other._y) < tolerance;
         }
 
-        public override bool Equals(object obj)
-        {
-            if (ReferenceEquals(null, obj))
-                return false;
-
-            return obj is Vector vector && Equals(vector);
-        }
+        public override bool Equals(object obj) => obj is Vector other && Equals(other);
 
         public override int GetHashCode()
         {

src/Avalonia.Visuals/VisualTree/TransformedBounds.cs

@@ -1,13 +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 System;
 
 namespace Avalonia.VisualTree
 {
     /// <summary>
     /// Holds information about the bounds of a control, together with a transform and a clip.
     /// </summary>
-    public readonly struct TransformedBounds
+    public readonly struct TransformedBounds : IEquatable<TransformedBounds>
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="TransformedBounds"/> struct.
@@ -56,15 +57,7 @@ namespace Avalonia.VisualTree
             return Bounds == other.Bounds && Clip == other.Clip && Transform == other.Transform;
         }
 
-        public override bool Equals(object obj)
-        {
-            if (obj is null)
-            {
-                return false;
-            }
-
-            return obj is TransformedBounds other && Equals(other);
-        }
+        public override bool Equals(object obj) => obj is TransformedBounds other && Equals(other);
 
         public override int GetHashCode()
         {

tests/Avalonia.Interactivity.UnitTests/InteractiveTests.cs

@@ -331,7 +331,7 @@ namespace Avalonia.Interactivity.UnitTests
 
             var target = CreateTree(ev, null, 0);
 
-            ev.AddClassHandler<TestInteractive>(x => x.ClassHandler, RoutingStrategies.Bubble);
+            ev.AddClassHandler<TestInteractive>((x, e) => x.ClassHandler(e), RoutingStrategies.Bubble);
 
             var args = new RoutedEventArgs(ev, target);
             target.RaiseEvent(args);