diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index 39333f37ba..3f4fbb0d50 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -32,7 +32,7 @@ jobs:
      
 - job: macOS
   pool:
-    vmImage: 'xcode9-macos10.13'
+    vmImage: 'macOS-10.14'
   steps:
   - task: DotNetCoreInstaller@0
     inputs:
@@ -49,7 +49,7 @@ jobs:
     inputs:
       actions: 'build'
       scheme: ''
-      sdk: 'macosx10.13'
+      sdk: 'macosx10.14'
       configuration: 'Release'
       xcWorkspacePath: '**/*.xcodeproj/project.xcworkspace'
       xcodeVersion: 'default' # Options: 8, 9, default, specifyPath
diff --git a/nukebuild/Numerge b/nukebuild/Numerge
index 4464343aef..aef10ae67d 160000
--- a/nukebuild/Numerge
+++ b/nukebuild/Numerge
@@ -1 +1 @@
-Subproject commit 4464343aef5c8ab7a42fcb20a483a6058199f8b8
+Subproject commit aef10ae67dc55c95f49b52a505a0be33bfa297a5
diff --git a/src/Avalonia.Controls.DataGrid/Collections/DataGridCollectionView.cs b/src/Avalonia.Controls.DataGrid/Collections/DataGridCollectionView.cs
index 4b4203ba40..92734b128d 100644
--- a/src/Avalonia.Controls.DataGrid/Collections/DataGridCollectionView.cs
+++ b/src/Avalonia.Controls.DataGrid/Collections/DataGridCollectionView.cs
@@ -927,7 +927,7 @@ namespace Avalonia.Collections
         /// <remarks>
         /// <p>
         /// Clear a sort criteria by assigning SortDescription.Empty to this property.
-        /// One or more sort criteria in form of <seealso cref="SortDescription"/>
+        /// One or more sort criteria in form of <seealso cref="DataGridSortDescription"/>
         /// can be used, each specifying a property and direction to sort by.
         /// </p>
         /// </remarks>
@@ -4312,4 +4312,4 @@ namespace Avalonia.Collections
             }
         }       
     }
-}
\ No newline at end of file
+}
diff --git a/src/Avalonia.Controls.DataGrid/Properties/AssemblyInfo.cs b/src/Avalonia.Controls.DataGrid/Properties/AssemblyInfo.cs
index d5ad4c75f8..f15442addf 100644
--- a/src/Avalonia.Controls.DataGrid/Properties/AssemblyInfo.cs
+++ b/src/Avalonia.Controls.DataGrid/Properties/AssemblyInfo.cs
@@ -8,7 +8,6 @@ using Avalonia.Metadata;
 [assembly: InternalsVisibleTo("Avalonia.Controls.UnitTests")]
 [assembly: InternalsVisibleTo("Avalonia.DesignerSupport")]
 
-[assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia")]
 [assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Controls")]
-[assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Controls.Primitives")]
 [assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Controls.Collections")]
+[assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Controls.Primitives")]
diff --git a/src/Avalonia.Controls/Grid.cs b/src/Avalonia.Controls/Grid.cs
index b51583d8b3..90a27d0b31 100644
--- a/src/Avalonia.Controls/Grid.cs
+++ b/src/Avalonia.Controls/Grid.cs
@@ -177,6 +177,17 @@ namespace Avalonia.Controls
             return element.GetValue(RowSpanProperty);
         }
 
+
+        /// <summary>
+        /// Gets the value of the IsSharedSizeScope attached property for a control.
+        /// </summary>
+        /// <param name="element">The control.</param>
+        /// <returns>The control's IsSharedSizeScope value.</returns>
+        public static bool GetIsSharedSizeScope(AvaloniaObject element)
+        {
+            return element.GetValue(IsSharedSizeScopeProperty);
+        }
+
         /// <summary>
         /// Sets the value of the Column attached property for a control.
         /// </summary>
@@ -217,6 +228,16 @@ namespace Avalonia.Controls
             element.SetValue(RowSpanProperty, value);
         }
 
+        /// <summary>
+        /// Sets the value of IsSharedSizeScope property for a control.
+        /// </summary>
+        /// <param name="element">The control.</param>
+        /// <param name="value">The IsSharedSizeScope value.</param>
+        public static void SetIsSharedSizeScope(AvaloniaObject element, bool value)
+        {
+            element.SetValue(IsSharedSizeScopeProperty, value);
+        }
+
         /// <summary>
         /// Gets the result of the last column measurement.
         /// Use this result to reduce the arrange calculation.
diff --git a/src/Avalonia.Controls/Image.cs b/src/Avalonia.Controls/Image.cs
index c696fe7975..fa6f5787be 100644
--- a/src/Avalonia.Controls/Image.cs
+++ b/src/Avalonia.Controls/Image.cs
@@ -81,23 +81,22 @@ namespace Avalonia.Controls
         protected override Size MeasureOverride(Size availableSize)
         {
             var source = Source;
+            var result = new Size();
 
             if (source != null)
             {
                 Size sourceSize = new Size(source.PixelSize.Width, source.PixelSize.Height);
                 if (double.IsInfinity(availableSize.Width) || double.IsInfinity(availableSize.Height))
                 {
-                    return sourceSize;
+                    result = sourceSize;
                 }
                 else
                 {
-                    return Stretch.CalculateSize(availableSize, sourceSize);
+                    result = Stretch.CalculateSize(availableSize, sourceSize);
                 }
             }
-            else
-            {
-                return new Size();
-            }
+
+            return result.Constrain(availableSize);
         }
 
         /// <inheritdoc/>
diff --git a/src/Avalonia.Controls/Platform/InProcessDragSource.cs b/src/Avalonia.Controls/Platform/InProcessDragSource.cs
index f8ae9f4249..0918da1a90 100644
--- a/src/Avalonia.Controls/Platform/InProcessDragSource.cs
+++ b/src/Avalonia.Controls/Platform/InProcessDragSource.cs
@@ -147,7 +147,10 @@ namespace Avalonia.Platform
                 e.Handled = true;
             }
             else if (e.Key == Key.LeftCtrl || e.Key == Key.RightCtrl || e.Key == Key.LeftAlt || e.Key == Key.RightAlt)
-                RaiseEventAndUpdateCursor(RawDragEventType.DragOver, _lastRoot, _lastPosition, e.Modifiers);
+            {
+                if (_lastRoot != null)
+                    RaiseEventAndUpdateCursor(RawDragEventType.DragOver, _lastRoot, _lastPosition, e.Modifiers);
+            }
         }
 
         private void ProcessMouseEvents(RawMouseEventArgs e)
diff --git a/src/Avalonia.Controls/Shapes/Shape.cs b/src/Avalonia.Controls/Shapes/Shape.cs
index 57dbeba1cc..499dfb5320 100644
--- a/src/Avalonia.Controls/Shapes/Shape.cs
+++ b/src/Avalonia.Controls/Shapes/Shape.cs
@@ -21,13 +21,19 @@ namespace Avalonia.Controls.Shapes
 
         public static readonly StyledProperty<AvaloniaList<double>> StrokeDashArrayProperty =
             AvaloniaProperty.Register<Shape, AvaloniaList<double>>(nameof(StrokeDashArray));
-            
+
         public static readonly StyledProperty<double> StrokeDashOffsetProperty =
             AvaloniaProperty.Register<Shape, double>(nameof(StrokeDashOffset));
 
         public static readonly StyledProperty<double> StrokeThicknessProperty =
             AvaloniaProperty.Register<Shape, double>(nameof(StrokeThickness));
 
+        public static readonly StyledProperty<PenLineCap> StrokeLineCapProperty =
+            AvaloniaProperty.Register<Shape, PenLineCap>(nameof(StrokeLineCap), PenLineCap.Flat);
+
+        public static readonly StyledProperty<PenLineJoin> StrokeJoinProperty =
+            AvaloniaProperty.Register<Shape, PenLineJoin>(nameof(StrokeJoin), PenLineJoin.Miter);
+
         private Matrix _transform = Matrix.Identity;
         private Geometry _definingGeometry;
         private Geometry _renderedGeometry;
@@ -36,7 +42,9 @@ namespace Avalonia.Controls.Shapes
         static Shape()
         {
             AffectsMeasure<Shape>(StretchProperty, StrokeThicknessProperty);
-            AffectsRender<Shape>(FillProperty, StrokeProperty, StrokeDashArrayProperty);
+
+            AffectsRender<Shape>(FillProperty, StrokeProperty, StrokeDashArrayProperty, StrokeDashOffsetProperty,
+                StrokeThicknessProperty, StrokeLineCapProperty, StrokeJoinProperty);
         }
 
         public Geometry DefiningGeometry
@@ -106,7 +114,7 @@ namespace Avalonia.Controls.Shapes
             get { return GetValue(StrokeDashArrayProperty); }
             set { SetValue(StrokeDashArrayProperty, value); }
         }
-        
+
         public double StrokeDashOffset
         {
             get { return GetValue(StrokeDashOffsetProperty); }
@@ -119,13 +127,17 @@ namespace Avalonia.Controls.Shapes
             set { SetValue(StrokeThicknessProperty, value); }
         }
 
-        public PenLineCap StrokeDashCap { get; set; } = PenLineCap.Flat;
-
-        public PenLineCap StrokeStartLineCap { get; set; } = PenLineCap.Flat;
-
-        public PenLineCap StrokeEndLineCap { get; set; } = PenLineCap.Flat;
+        public PenLineCap StrokeLineCap
+        {
+            get { return GetValue(StrokeLineCapProperty); }
+            set { SetValue(StrokeLineCapProperty, value); }
+        }
 
-        public PenLineJoin StrokeJoin { get; set; } = PenLineJoin.Miter;
+        public PenLineJoin StrokeJoin
+        {
+            get { return GetValue(StrokeJoinProperty); }
+            set { SetValue(StrokeJoinProperty, value); }
+        }
 
         public override void Render(DrawingContext context)
         {
@@ -133,8 +145,8 @@ namespace Avalonia.Controls.Shapes
 
             if (geometry != null)
             {
-                var pen = new Pen(Stroke, StrokeThickness, new DashStyle(StrokeDashArray, StrokeDashOffset), 
-                    StrokeDashCap, StrokeStartLineCap, StrokeEndLineCap, StrokeJoin);
+                var pen = new Pen(Stroke, StrokeThickness, new DashStyle(StrokeDashArray, StrokeDashOffset),
+                     StrokeLineCap, StrokeJoin);
                 context.DrawGeometry(Fill, pen, geometry);
             }
         }
@@ -169,11 +181,11 @@ namespace Avalonia.Controls.Shapes
 
         protected void InvalidateGeometry()
         {
-            this._renderedGeometry = null;
-            this._definingGeometry = null;
+            _renderedGeometry = null;
+            _definingGeometry = null;
             InvalidateMeasure();
         }
-        
+
         protected override Size MeasureOverride(Size availableSize)
         {
             bool deferCalculateTransform;
@@ -203,10 +215,10 @@ namespace Avalonia.Controls.Shapes
                 return CalculateShapeSizeAndSetTransform(availableSize);
             }
         }
-        
+
         protected override Size ArrangeOverride(Size finalSize)
         {
-            if(_calculateTransformOnArrange)
+            if (_calculateTransformOnArrange)
             {
                 _calculateTransformOnArrange = false;
                 CalculateShapeSizeAndSetTransform(finalSize);
@@ -312,25 +324,25 @@ namespace Avalonia.Controls.Shapes
 
         private static void AffectsGeometryInvalidate(AvaloniaPropertyChangedEventArgs e)
         {
-            var control = e.Sender as Shape;
+            if (!(e.Sender is Shape control))
+            {
+                return;
+            }
 
-            if (control != null)
+            // If the geometry is invalidated when Bounds changes, only invalidate when the Size
+            // portion changes.
+            if (e.Property == BoundsProperty)
             {
-                // If the geometry is invalidated when Bounds changes, only invalidate when the Size
-                // portion changes.
-                if (e.Property == BoundsProperty)
-                {
-                    var oldBounds = (Rect)e.OldValue;
-                    var newBounds = (Rect)e.NewValue;
+                var oldBounds = (Rect)e.OldValue;
+                var newBounds = (Rect)e.NewValue;
 
-                    if (oldBounds.Size == newBounds.Size)
-                    {
-                        return;
-                    }
+                if (oldBounds.Size == newBounds.Size)
+                {
+                    return;
                 }
-
-                control.InvalidateGeometry();
             }
+
+            control.InvalidateGeometry();
         }
     }
 }
diff --git a/src/Avalonia.Controls/StackPanel.cs b/src/Avalonia.Controls/StackPanel.cs
index df0c113cc0..d89df8556b 100644
--- a/src/Avalonia.Controls/StackPanel.cs
+++ b/src/Avalonia.Controls/StackPanel.cs
@@ -4,6 +4,7 @@
 using System;
 using System.Linq;
 using Avalonia.Input;
+using Avalonia.Layout;
 
 namespace Avalonia.Controls
 {
@@ -219,30 +220,16 @@ namespace Avalonia.Controls
                 measuredWidth -= (hasVisibleChild ? spacing : 0);
             }
 
-            return new Size(measuredWidth, measuredHeight);
+            return new Size(measuredWidth, measuredHeight).Constrain(availableSize);
         }
 
-        /// <summary>
-        /// Arranges the control's children.
-        /// </summary>
-        /// <param name="finalSize">The size allocated to the control.</param>
-        /// <returns>The space taken.</returns>
+        /// <inheritdoc/>
         protected override Size ArrangeOverride(Size finalSize)
         {
             var orientation = Orientation;
-            double arrangedWidth = finalSize.Width;
-            double arrangedHeight = finalSize.Height;
-            double spacing = Spacing;
-            bool hasVisibleChild = Children.Any(c => c.IsVisible);
-
-            if (Orientation == Orientation.Vertical)
-            {
-                arrangedHeight = 0;
-            }
-            else
-            {
-                arrangedWidth = 0;
-            }
+            var spacing = Spacing;
+            var finalRect = new Rect(finalSize);
+            var pos = 0.0;
 
             foreach (Control child in Children)
             {
@@ -251,32 +238,21 @@ namespace Avalonia.Controls
 
                 if (orientation == Orientation.Vertical)
                 {
-                    double width = Math.Max(childWidth, arrangedWidth);
-                    Rect childFinal = new Rect(0, arrangedHeight, width, childHeight);
-                    ArrangeChild(child, childFinal, finalSize, orientation);
-                    arrangedWidth = Math.Max(arrangedWidth, childWidth);
-                    arrangedHeight += childHeight + (child.IsVisible ? spacing : 0);
+                    var rect = new Rect(0, pos, childWidth, childHeight)
+                        .Align(finalRect, child.HorizontalAlignment, VerticalAlignment.Top);
+                    ArrangeChild(child, rect, finalSize, orientation);
+                    pos += childHeight + spacing;
                 }
                 else
                 {
-                    double height = Math.Max(childHeight, arrangedHeight);
-                    Rect childFinal = new Rect(arrangedWidth, 0, childWidth, height);
-                    ArrangeChild(child, childFinal, finalSize, orientation);
-                    arrangedWidth += childWidth + (child.IsVisible ? spacing : 0);
-                    arrangedHeight = Math.Max(arrangedHeight, childHeight);
+                    var rect = new Rect(pos, 0, childWidth, childHeight)
+                        .Align(finalRect, HorizontalAlignment.Left, child.VerticalAlignment);
+                    ArrangeChild(child, rect, finalSize, orientation);
+                    pos += childWidth + spacing;
                 }
             }
 
-            if (orientation == Orientation.Vertical)
-            {
-                arrangedHeight = Math.Max(arrangedHeight - (hasVisibleChild ? spacing : 0), finalSize.Height);
-            }
-            else
-            {
-                arrangedWidth = Math.Max(arrangedWidth - (hasVisibleChild ? spacing : 0), finalSize.Width);
-            }
-
-            return new Size(arrangedWidth, arrangedHeight);
+            return finalSize;
         }
 
         internal virtual void ArrangeChild(
diff --git a/src/Avalonia.Controls/Viewbox.cs b/src/Avalonia.Controls/Viewbox.cs
index 3a070d07b2..781c93bcbe 100644
--- a/src/Avalonia.Controls/Viewbox.cs
+++ b/src/Avalonia.Controls/Viewbox.cs
@@ -49,7 +49,7 @@ namespace Avalonia.Controls
 
                 var scale = GetScale(availableSize, childSize, Stretch);
 
-                return childSize * scale;
+                return (childSize * scale).Constrain(availableSize);
             }
 
             return new Size();
diff --git a/src/Avalonia.Layout/LayoutExtensions.cs b/src/Avalonia.Layout/LayoutExtensions.cs
new file mode 100644
index 0000000000..737bbb083c
--- /dev/null
+++ b/src/Avalonia.Layout/LayoutExtensions.cs
@@ -0,0 +1,62 @@
+using System;
+
+namespace Avalonia.Layout
+{
+    /// <summary>
+    /// Extension methods for layout types.
+    /// </summary>
+    public static class LayoutExtensions
+    {
+        /// <summary>
+        /// Aligns a rect in a constraining rect according to horizontal and vertical alignment
+        /// settings.
+        /// </summary>
+        /// <param name="rect">The rect to align.</param>
+        /// <param name="constraint">The constraining rect.</param>
+        /// <param name="horizontalAlignment">The horizontal alignment.</param>
+        /// <param name="verticalAlignment">The vertical alignment.</param>
+        /// <returns></returns>
+        public static Rect Align(
+            this Rect rect,
+            Rect constraint,
+            HorizontalAlignment horizontalAlignment,
+            VerticalAlignment verticalAlignment)
+        {
+            switch (horizontalAlignment)
+            {
+                case HorizontalAlignment.Center:
+                    rect = rect.WithX((constraint.Width - rect.Width) / 2);
+                    break;
+                case HorizontalAlignment.Right:
+                    rect = rect.WithX(constraint.Width - rect.Width);
+                    break;
+                case HorizontalAlignment.Stretch:
+                    rect = new Rect(
+                        0,
+                        rect.Y,
+                        Math.Max(constraint.Width, rect.Width),
+                        rect.Height);
+                    break;
+            }
+
+            switch (verticalAlignment)
+            {
+                case VerticalAlignment.Center:
+                    rect = rect.WithY((constraint.Height - rect.Height) / 2);
+                    break;
+                case VerticalAlignment.Bottom:
+                    rect = rect.WithY(constraint.Height - rect.Height);
+                    break;
+                case VerticalAlignment.Stretch:
+                    rect = new Rect(
+                        rect.X,
+                        0,
+                        rect.Width,
+                        Math.Max(constraint.Height, rect.Height));
+                    break;
+            }
+
+            return rect;
+        }
+    }
+}
diff --git a/src/Avalonia.Layout/Layoutable.cs b/src/Avalonia.Layout/Layoutable.cs
index d5e3a1631e..662f48ec44 100644
--- a/src/Avalonia.Layout/Layoutable.cs
+++ b/src/Avalonia.Layout/Layoutable.cs
@@ -314,7 +314,7 @@ namespace Avalonia.Layout
                 try
                 {
                     _measuring = true;
-                    desiredSize = MeasureCore(availableSize).Constrain(availableSize);
+                    desiredSize = MeasureCore(availableSize);
                 }
                 finally
                 {
diff --git a/src/Avalonia.Themes.Default/ScrollBar.xaml b/src/Avalonia.Themes.Default/ScrollBar.xaml
index 2cb8ce2d24..ca308b33c3 100644
--- a/src/Avalonia.Themes.Default/ScrollBar.xaml
+++ b/src/Avalonia.Themes.Default/ScrollBar.xaml
@@ -30,13 +30,7 @@
                                               Classes="repeattrack"
                                               Focusable="False"/>
                             </Track.IncreaseButton>
-                            <Thumb Name="thumb">
-                                <Thumb.Template>
-                                    <ControlTemplate>
-                                        <Border Background="{DynamicResource ThemeControlHighBrush}" />
-                                    </ControlTemplate>
-                                </Thumb.Template>
-                            </Thumb>
+                            <Thumb Name="thumb"/>
                         </Track>
                         <RepeatButton Name="PART_LineDownButton"
                                       Classes="repeat"
@@ -84,13 +78,7 @@
                                               Classes="repeattrack"
                                               Focusable="False"/>
                             </Track.IncreaseButton>
-                            <Thumb Name="thumb">
-                                <Thumb.Template>
-                                    <ControlTemplate>
-                                        <Border Background="{DynamicResource ThemeControlHighBrush}" />
-                                    </ControlTemplate>
-                                </Thumb.Template>
-                            </Thumb>
+                            <Thumb Name="thumb"/>
                         </Track>
                         <RepeatButton Name="PART_LineDownButton"
                                       Classes="repeat"
@@ -106,6 +94,16 @@
             </ControlTemplate>
         </Setter>
     </Style>
+    <Style Selector="ScrollBar /template/ Thumb#thumb">
+        <Setter Property="Background" Value="{DynamicResource ThemeControlHighBrush}"/>
+        <Setter Property="Template">
+            <Setter.Value>
+                <ControlTemplate>
+                    <Border Background="{TemplateBinding Background}"/>
+                </ControlTemplate>
+            </Setter.Value>
+        </Setter>
+    </Style>
     <Style Selector="ScrollBar:horizontal /template/ Thumb#thumb">
         <Setter Property="MinWidth" Value="{DynamicResource ScrollBarThickness}" />
     </Style>
diff --git a/src/Avalonia.Visuals/Media/BrushExtensions.cs b/src/Avalonia.Visuals/Media/BrushExtensions.cs
index cd351071dd..522953eb04 100644
--- a/src/Avalonia.Visuals/Media/BrushExtensions.cs
+++ b/src/Avalonia.Visuals/Media/BrushExtensions.cs
@@ -34,16 +34,14 @@ namespace Avalonia.Media
         {
             Contract.Requires<ArgumentNullException>(pen != null);
 
-            var brush = pen?.Brush?.ToImmutable();
-            return pen == null || ReferenceEquals(pen?.Brush, brush) ?
+            var brush = pen.Brush?.ToImmutable();
+            return ReferenceEquals(pen.Brush, brush) ?
                 pen :
                 new Pen(
                     brush,
                     thickness: pen.Thickness,
-                    dashStyle: pen.DashStyle,
-                    dashCap: pen.DashCap,
-                    startLineCap: pen.StartLineCap,
-                    endLineCap: pen.EndLineCap,
+                    dashStyle: pen.DashStyle,                   
+                    lineCap: pen.LineCap,
                     lineJoin: pen.LineJoin,
                     miterLimit: pen.MiterLimit);
         }
diff --git a/src/Avalonia.Visuals/Media/Pen.cs b/src/Avalonia.Visuals/Media/Pen.cs
index ddd8091801..ee427c913b 100644
--- a/src/Avalonia.Visuals/Media/Pen.cs
+++ b/src/Avalonia.Visuals/Media/Pen.cs
@@ -11,63 +11,45 @@ namespace Avalonia.Media
         /// <summary>
         /// Initializes a new instance of the <see cref="Pen"/> class.
         /// </summary>
-        /// <param name="brush">The brush used to draw.</param>
+        /// <param name="color">The stroke color.</param>
         /// <param name="thickness">The stroke thickness.</param>
         /// <param name="dashStyle">The dash style.</param>
-        /// <param name="dashCap">The dash cap.</param>
-        /// <param name="startLineCap">The start line cap.</param>
-        /// <param name="endLineCap">The end line cap.</param>
+        /// <param name="lineCap">Specifies the type of graphic shape to use on both ends of a line.</param>
         /// <param name="lineJoin">The line join.</param>
         /// <param name="miterLimit">The miter limit.</param>
         public Pen(
-            IBrush brush, 
+            uint color,
             double thickness = 1.0,
-            DashStyle dashStyle = null, 
-            PenLineCap dashCap = PenLineCap.Flat, 
-            PenLineCap startLineCap = PenLineCap.Flat, 
-            PenLineCap endLineCap = PenLineCap.Flat, 
-            PenLineJoin lineJoin = PenLineJoin.Miter, 
-            double miterLimit = 10.0)
+            DashStyle dashStyle = null,
+            PenLineCap lineCap = PenLineCap.Flat,
+            PenLineJoin lineJoin = PenLineJoin.Miter,
+            double miterLimit = 10.0) : this(new SolidColorBrush(color), thickness, dashStyle, lineCap, lineJoin, miterLimit)
         {
-            Brush = brush;
-            Thickness = thickness;
-            DashCap = dashCap;
-            StartLineCap = startLineCap;
-            EndLineCap = endLineCap;
-            LineJoin = lineJoin;
-            MiterLimit = miterLimit;
-            DashStyle = dashStyle;
         }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="Pen"/> class.
         /// </summary>
-        /// <param name="color">The stroke color.</param>
+        /// <param name="brush">The brush used to draw.</param>
         /// <param name="thickness">The stroke thickness.</param>
         /// <param name="dashStyle">The dash style.</param>
-        /// <param name="dashCap">The dash cap.</param>
-        /// <param name="startLineCap">The start line cap.</param>
-        /// <param name="endLineCap">The end line cap.</param>
+        /// <param name="lineCap">The line cap.</param>
         /// <param name="lineJoin">The line join.</param>
         /// <param name="miterLimit">The miter limit.</param>
         public Pen(
-            uint color, 
+            IBrush brush,
             double thickness = 1.0,
-            DashStyle dashStyle = null, 
-            PenLineCap dashCap = PenLineCap.Flat, 
-            PenLineCap startLineCap = PenLineCap.Flat,
-            PenLineCap endLineCap = PenLineCap.Flat, 
-            PenLineJoin lineJoin = PenLineJoin.Miter, 
+            DashStyle dashStyle = null,
+            PenLineCap lineCap = PenLineCap.Flat,
+            PenLineJoin lineJoin = PenLineJoin.Miter,
             double miterLimit = 10.0)
         {
-            Brush = new SolidColorBrush(color);
+            Brush = brush;
             Thickness = thickness;
-            StartLineCap = startLineCap;
-            EndLineCap = endLineCap;
+            LineCap = lineCap;
             LineJoin = lineJoin;
             MiterLimit = miterLimit;
             DashStyle = dashStyle;
-            DashCap = dashCap;
         }
 
         /// <summary>
@@ -78,18 +60,26 @@ namespace Avalonia.Media
         /// <summary>
         /// Gets the stroke thickness.
         /// </summary>
-        public double Thickness { get; } = 1.0;
+        public double Thickness { get; }
 
+        /// <summary>
+        /// Specifies the style of dashed lines drawn with a <see cref="Pen"/> object.
+        /// </summary>
         public DashStyle DashStyle { get; }
 
-        public PenLineCap DashCap { get; }
-
-        public PenLineCap StartLineCap { get; } = PenLineCap.Flat;
-
-        public PenLineCap EndLineCap { get; } = PenLineCap.Flat;
+        /// <summary>
+        /// Specifies the type of graphic shape to use on both ends of a line.
+        /// </summary>
+        public PenLineCap LineCap { get; }
 
-        public PenLineJoin LineJoin { get; } = PenLineJoin.Miter;
+        /// <summary>
+        /// Specifies how to join consecutive line or curve segments in a <see cref="PathFigure"/> (subpath) contained in a <see cref="PathGeometry"/> object.
+        /// </summary>
+        public PenLineJoin LineJoin { get; }
 
-        public double MiterLimit { get; } = 10.0;
+        /// <summary>
+        /// The limit on the ratio of the miter length to half this pen's Thickness.
+        /// </summary>
+        public double MiterLimit { get; }
     }
 }
diff --git a/src/Avalonia.Visuals/Media/PenLineCap.cs b/src/Avalonia.Visuals/Media/PenLineCap.cs
index 56c5c040eb..83d8f11613 100644
--- a/src/Avalonia.Visuals/Media/PenLineCap.cs
+++ b/src/Avalonia.Visuals/Media/PenLineCap.cs
@@ -4,7 +4,6 @@ namespace Avalonia.Media
     {
         Flat,
         Round,
-        Square,
-        Triangle
+        Square
     }
 }
diff --git a/src/Skia/Avalonia.Skia/DrawingContextImpl.cs b/src/Skia/Avalonia.Skia/DrawingContextImpl.cs
index 5272f4b22d..ee4564ff35 100644
--- a/src/Skia/Avalonia.Skia/DrawingContextImpl.cs
+++ b/src/Skia/Avalonia.Skia/DrawingContextImpl.cs
@@ -578,25 +578,17 @@ namespace Avalonia.Skia
             // Need to modify dashes due to Skia modifying their lengths
             // https://docs.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/graphics/skiasharp/paths/dots
             // TODO: Still something is off, dashes are now present, but don't look the same as D2D ones.
-            float dashLengthModifier;
-            float gapLengthModifier;
 
-            switch (pen.StartLineCap)
+            switch (pen.LineCap)
             {
                 case PenLineCap.Round:
                     paint.StrokeCap = SKStrokeCap.Round;
-                    dashLengthModifier = -paint.StrokeWidth;
-                    gapLengthModifier = paint.StrokeWidth;
                     break;
                 case PenLineCap.Square:
                     paint.StrokeCap = SKStrokeCap.Square;
-                    dashLengthModifier = -paint.StrokeWidth;
-                    gapLengthModifier = paint.StrokeWidth;
                     break;
                 default:
                     paint.StrokeCap = SKStrokeCap.Butt;
-                    dashLengthModifier = 0.0f;
-                    gapLengthModifier = 0.0f;
                     break;
             }
 
@@ -622,13 +614,12 @@ namespace Avalonia.Skia
 
                 for (var i = 0; i < srcDashes.Count; ++i)
                 {
-                    var lengthModifier = i % 2 == 0 ? dashLengthModifier : gapLengthModifier;
-
-                    // Avalonia dash lengths are relative, but Skia takes absolute sizes - need to scale
-                    dashesArray[i] = (float) srcDashes[i] * paint.StrokeWidth + lengthModifier;
+                    dashesArray[i] = (float) srcDashes[i] * paint.StrokeWidth;
                 }
 
-                var pe = SKPathEffect.CreateDash(dashesArray, (float) pen.DashStyle.Offset);
+                var offset = (float)(pen.DashStyle.Offset * pen.Thickness);
+
+                var pe = SKPathEffect.CreateDash(dashesArray, offset);
 
                 paint.PathEffect = pe;
                 rv.AddDisposable(pe);
diff --git a/src/Windows/Avalonia.Direct2D1/PrimitiveExtensions.cs b/src/Windows/Avalonia.Direct2D1/PrimitiveExtensions.cs
index 5209014271..6b0d30f250 100644
--- a/src/Windows/Avalonia.Direct2D1/PrimitiveExtensions.cs
+++ b/src/Windows/Avalonia.Direct2D1/PrimitiveExtensions.cs
@@ -122,14 +122,16 @@ namespace Avalonia.Direct2D1
         /// <returns>The Direct2D brush.</returns>
         public static StrokeStyle ToDirect2DStrokeStyle(this Avalonia.Media.Pen pen, Factory factory)
         {
+            var d2dLineCap = pen.LineCap.ToDirect2D();
+
             var properties = new StrokeStyleProperties
             {
                 DashStyle = DashStyle.Solid,
                 MiterLimit = (float)pen.MiterLimit,
                 LineJoin = pen.LineJoin.ToDirect2D(),
-                StartCap = pen.StartLineCap.ToDirect2D(),
-                EndCap = pen.EndLineCap.ToDirect2D(),
-                DashCap = pen.DashCap.ToDirect2D()
+                StartCap = d2dLineCap,
+                EndCap = d2dLineCap,
+                DashCap = d2dLineCap
             };
             float[] dashes = null;
             if (pen.DashStyle?.Dashes != null && pen.DashStyle.Dashes.Count > 0)
diff --git a/tests/Avalonia.Controls.UnitTests/StackPanelTests.cs b/tests/Avalonia.Controls.UnitTests/StackPanelTests.cs
index ba2716775a..722ad1c8ee 100644
--- a/tests/Avalonia.Controls.UnitTests/StackPanelTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/StackPanelTests.cs
@@ -1,7 +1,8 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
-using Avalonia.Controls;
+using System.Linq;
+using Avalonia.Layout;
 using Xunit;
 
 namespace Avalonia.Controls.UnitTests
@@ -147,6 +148,151 @@ namespace Avalonia.Controls.UnitTests
             Assert.Equal(new Rect(50, 0, 50, 120), target.Children[2].Bounds);
         }
 
+        [Fact]
+        public void Arranges_Vertical_Children_With_Correct_Bounds()
+        {
+            var target = new StackPanel
+            {
+                Orientation = Orientation.Vertical,
+                Children =
+                {
+                    new TestControl
+                    {
+                        HorizontalAlignment = HorizontalAlignment.Left,
+                        MeasureSize = new Size(50, 10),
+                    },
+                    new TestControl
+                    {
+                        HorizontalAlignment = HorizontalAlignment.Left,
+                        MeasureSize = new Size(150, 10),
+                    },
+                    new TestControl
+                    {
+                        HorizontalAlignment = HorizontalAlignment.Center,
+                        MeasureSize = new Size(50, 10),
+                    },
+                    new TestControl
+                    {
+                        HorizontalAlignment = HorizontalAlignment.Center,
+                        MeasureSize = new Size(150, 10),
+                    },
+                    new TestControl
+                    {
+                        HorizontalAlignment = HorizontalAlignment.Right,
+                        MeasureSize = new Size(50, 10),
+                    },
+                    new TestControl
+                    {
+                        HorizontalAlignment = HorizontalAlignment.Right,
+                        MeasureSize = new Size(150, 10),
+                    },
+                    new TestControl
+                    {
+                        HorizontalAlignment = HorizontalAlignment.Stretch,
+                        MeasureSize = new Size(50, 10),
+                    },
+                    new TestControl
+                    {
+                        HorizontalAlignment = HorizontalAlignment.Stretch,
+                        MeasureSize = new Size(150, 10),
+                    },
+                }
+            };
+
+            target.Measure(new Size(100, 150));
+            Assert.Equal(new Size(100, 80), target.DesiredSize);
+
+            target.Arrange(new Rect(target.DesiredSize));
+
+            var bounds = target.Children.Select(x => x.Bounds).ToArray();
+
+            Assert.Equal(
+                new[]
+                {
+                    new Rect(0, 0, 50, 10),
+                    new Rect(0, 10, 150, 10),
+                    new Rect(25, 20, 50, 10),
+                    new Rect(-25, 30, 150, 10),
+                    new Rect(50, 40, 50, 10),
+                    new Rect(-50, 50, 150, 10),
+                    new Rect(0, 60, 100, 10),
+                    new Rect(0, 70, 150, 10),
+
+                }, bounds);
+        }
+
+        [Fact]
+        public void Arranges_Horizontal_Children_With_Correct_Bounds()
+        {
+            var target = new StackPanel
+            {
+                Orientation = Orientation.Horizontal,
+                Children =
+                {
+                    new TestControl
+                    {
+                        VerticalAlignment = VerticalAlignment.Top,
+                        MeasureSize = new Size(10, 50),
+                    },
+                    new TestControl
+                    {
+                        VerticalAlignment = VerticalAlignment.Top,
+                        MeasureSize = new Size(10, 150),
+                    },
+                    new TestControl
+                    {
+                        VerticalAlignment = VerticalAlignment.Center,
+                        MeasureSize = new Size(10, 50),
+                    },
+                    new TestControl
+                    {
+                        VerticalAlignment = VerticalAlignment.Center,
+                        MeasureSize = new Size(10, 150),
+                    },
+                    new TestControl
+                    {
+                        VerticalAlignment = VerticalAlignment.Bottom,
+                        MeasureSize = new Size(10, 50),
+                    },
+                    new TestControl
+                    {
+                        VerticalAlignment = VerticalAlignment.Bottom,
+                        MeasureSize = new Size(10, 150),
+                    },
+                    new TestControl
+                    {
+                        VerticalAlignment = VerticalAlignment.Stretch,
+                        MeasureSize = new Size(10, 50),
+                    },
+                    new TestControl
+                    {
+                        VerticalAlignment = VerticalAlignment.Stretch,
+                        MeasureSize = new Size(10, 150),
+                    },
+                }
+            };
+
+            target.Measure(new Size(150, 100));
+            Assert.Equal(new Size(80, 100), target.DesiredSize);
+
+            target.Arrange(new Rect(target.DesiredSize));
+
+            var bounds = target.Children.Select(x => x.Bounds).ToArray();
+
+            Assert.Equal(
+                new[]
+                {
+                    new Rect(0, 0, 10, 50),
+                    new Rect(10, 0, 10, 150),
+                    new Rect(20, 25, 10, 50),
+                    new Rect(30, -25, 10, 150),
+                    new Rect(40, 50, 10, 50),
+                    new Rect(50, -50, 10, 150),
+                    new Rect(60, 0, 10, 100),
+                    new Rect(70, 0, 10, 150),
+                }, bounds);
+        }
+
         [Theory]
         [InlineData(Orientation.Horizontal)]
         [InlineData(Orientation.Vertical)]
@@ -185,5 +331,17 @@ namespace Avalonia.Controls.UnitTests
 
             Assert.Equal(sizeWithTwoChildren, sizeWithThreeChildren);
         }
+
+        private class TestControl : Control
+        {
+            public Size MeasureConstraint { get; private set; }
+            public Size MeasureSize { get; set; }
+
+            protected override Size MeasureOverride(Size availableSize)
+            {
+                MeasureConstraint = availableSize;
+                return MeasureSize;
+            }
+        }
     }
 }
diff --git a/tests/Avalonia.RenderTests/Shapes/PathTests.cs b/tests/Avalonia.RenderTests/Shapes/PathTests.cs
index 4703daca25..2fa93b49e2 100644
--- a/tests/Avalonia.RenderTests/Shapes/PathTests.cs
+++ b/tests/Avalonia.RenderTests/Shapes/PathTests.cs
@@ -334,11 +334,7 @@ namespace Avalonia.Direct2D1.RenderTests.Shapes
             CompareImages();
         }
 
-#if AVALONIA_SKIA_SKIP_FAIL
-        [Fact(Skip = "FIXME")]
-#else
         [Fact]
-#endif
         public async Task Path_With_PenLineCap()
         {
             Decorator target = new Decorator
@@ -351,10 +347,8 @@ namespace Avalonia.Direct2D1.RenderTests.Shapes
                     StrokeThickness = 10,
                     HorizontalAlignment = HorizontalAlignment.Center,
                     VerticalAlignment = VerticalAlignment.Center,
-                    StrokeDashCap = PenLineCap.Triangle,
                     StrokeDashArray = new AvaloniaList<double>(3, 1),
-                    StrokeStartLineCap = PenLineCap.Round,
-                    StrokeEndLineCap = PenLineCap.Square,
+                    StrokeLineCap = PenLineCap.Round,
                     Data = StreamGeometry.Parse("M 20,20 L 180,180"),
                 }
             };
diff --git a/tests/Avalonia.RenderTests/Shapes/PolylineTests.cs b/tests/Avalonia.RenderTests/Shapes/PolylineTests.cs
index 3b586d55ea..8afaeb8838 100644
--- a/tests/Avalonia.RenderTests/Shapes/PolylineTests.cs
+++ b/tests/Avalonia.RenderTests/Shapes/PolylineTests.cs
@@ -61,8 +61,7 @@ namespace Avalonia.Direct2D1.RenderTests.Shapes
                     Points = polylinePoints,
                     Stretch = Stretch.Uniform,
                     StrokeJoin = PenLineJoin.Round,
-                    StrokeStartLineCap = PenLineCap.Round,
-                    StrokeEndLineCap = PenLineCap.Round,
+                    StrokeLineCap = PenLineCap.Round,
                     StrokeThickness = 10
                 }
             };
diff --git a/tests/TestFiles/Direct2D1/Shapes/Path/Path_With_PenLineCap.expected.png b/tests/TestFiles/Direct2D1/Shapes/Path/Path_With_PenLineCap.expected.png
index d33068d62c..a61ba9f080 100644
Binary files a/tests/TestFiles/Direct2D1/Shapes/Path/Path_With_PenLineCap.expected.png and b/tests/TestFiles/Direct2D1/Shapes/Path/Path_With_PenLineCap.expected.png differ
diff --git a/tests/TestFiles/Skia/Shapes/Path/Path_With_PenLineCap.expected.png b/tests/TestFiles/Skia/Shapes/Path/Path_With_PenLineCap.expected.png
index d33068d62c..a61ba9f080 100644
Binary files a/tests/TestFiles/Skia/Shapes/Path/Path_With_PenLineCap.expected.png and b/tests/TestFiles/Skia/Shapes/Path/Path_With_PenLineCap.expected.png differ