Began implementing geometry

Cairo/Perspex.Cairo/CairoExtensions.cs

@@ -37,24 +37,51 @@ namespace Perspex.Cairo
         public static Pango.Weight ToCairo(this Perspex.Media.FontWeight weight)
         {
             if (weight == Perspex.Media.FontWeight.Light)
+            {
                 return Pango.Weight.Light;
+            }
 
             if (weight == Perspex.Media.FontWeight.Normal || weight == Perspex.Media.FontWeight.Regular)
+            {
                 return Pango.Weight.Normal;
+            }
 
             if (weight == Perspex.Media.FontWeight.DemiBold || weight == Perspex.Media.FontWeight.Medium)
+            {
                 return Pango.Weight.Semibold;
+            }
 
             if (weight == Perspex.Media.FontWeight.Bold)
+            {
                 return Pango.Weight.Bold;
+            }
 
             if (weight == Perspex.Media.FontWeight.UltraBold || weight == Perspex.Media.FontWeight.ExtraBold)
+            {
                 return Pango.Weight.Ultrabold;
+            }
 
             if (weight == Perspex.Media.FontWeight.Black || weight == Perspex.Media.FontWeight.Heavy || weight == Perspex.Media.FontWeight.UltraBlack)
+            {
                 return Pango.Weight.Heavy;
+            }
 
             return Pango.Weight.Ultralight;
         }
+
+        public static Pango.Alignment ToCairo(this Perspex.Media.TextAlignment alignment)
+        {
+            if (alignment == Perspex.Media.TextAlignment.Left)
+            {
+                return Pango.Alignment.Left;
+            }
+
+            if (alignment == Perspex.Media.TextAlignment.Center)
+            {
+                return Pango.Alignment.Center;
+            }
+
+            return Pango.Alignment.Right;
+        }
     }
 }

Cairo/Perspex.Cairo/CairoPlatform.cs

@@ -35,9 +35,10 @@ namespace Perspex.Cairo
             string fontFamily, 
             double fontSize, 
             FontStyle fontStyle,
+            TextAlignment textAlignment,
             Perspex.Media.FontWeight fontWeight)
         {
-            return new FormattedTextImpl(text, fontFamily, fontSize, fontStyle, fontWeight);
+            return new FormattedTextImpl(text, fontFamily, fontSize, fontStyle, textAlignment, fontWeight);
         }
 
         public IRenderer CreateRenderer(IPlatformHandle handle, double width, double height)

Cairo/Perspex.Cairo/Media/DrawingContext.cs

@@ -118,53 +118,57 @@ namespace Perspex.Cairo.Media
         {
             var impl = geometry.PlatformImpl as StreamGeometryImpl;
             var clone = new Queue<GeometryOp>(impl.Operations);
-            bool useFill = false;
-            
-            var pop = this.PushTransform(impl.Transform);
 
+            bool useFill = false;
+      
             this.SetPen(pen);
+            this.SetBrush(brush);
 
-            while (clone.Count > 0)
+            using (var pop = this.PushTransform(impl.Transform))
             {
+                while (clone.Count > 0)
+                {
 
-                var current = clone.Dequeue();
+                    var current = clone.Dequeue();
 
-                if (current is BeginOp)
+                    if (current is BeginOp)
-                {
+                    {
-                    var bo = current as BeginOp;
+                        var bo = current as BeginOp;
-                    this.context.MoveTo(bo.Point.ToCairo());
+                        this.context.MoveTo(bo.Point.ToCairo());
 
-                    useFill = bo.IsFilled;
+                        useFill = bo.IsFilled;
-                }
+
-                else if (current is LineToOp)
+                        System.Diagnostics.Debug.WriteLine("Start");
-                {
+                    }
-                    var lto = current as LineToOp;
+                    else if (current is LineToOp)
-                    this.context.LineTo(lto.Point.ToCairo());
+                    {
+                        var lto = current as LineToOp;
+                        this.context.LineTo(lto.Point.ToCairo());
+                    }
+                    else if (current is EndOp)
+                    {
+                        if (((EndOp)current).IsClosed)
+                            this.context.ClosePath();
+
+                        System.Diagnostics.Debug.WriteLine("End");
+                    }
+                    else if (current is CurveToOp)
+                    {
+                        var cto = current as CurveToOp;
+                        this.context.CurveTo(cto.Point.ToCairo(), cto.Point2.ToCairo(), cto.Point3.ToCairo());
+                    }
                 }
-                else if (current is EndOp)
+
+                System.Diagnostics.Debug.WriteLine("Render");
+                if (useFill)
                 {
-                    if (((EndOp)current).IsClosed)
+                    this.context.FillPreserve();
-                        this.context.ClosePath();
                 }
-                else if (current is CurveToOp)
+                else
                 {
-                    var cto = current as CurveToOp;
+                    this.context.StrokePreserve();
-                    this.context.CurveTo(cto.Point.ToCairo(), cto.Point2.ToCairo(), cto.Point3.ToCairo());
                 }
-             
             }
-
-            if (useFill)
-            {
-                this.context.StrokePreserve();
-                this.context.Fill();
-            }
-            else
-            {
-                this.context.Stroke();
-            }
-
-            pop.Dispose();
         }
 
         /// <summary>
@@ -220,6 +224,17 @@ namespace Perspex.Cairo.Media
             return Disposable.Create(() => this.context.ResetClip());
         }
 
+        /// <summary>
+        /// Pushes an opacity value.
+        /// </summary>
+        /// <param name="opacity">The opacity.</param>
+        /// <returns>A disposable used to undo the opacity.</returns>
+        public IDisposable PushOpacity(double opacity)
+        {
+            // TODO: Implement
+            return Disposable.Empty;
+        }
+
         /// <summary>
         /// Pushes a matrix transformation.
         /// </summary>
@@ -253,6 +268,7 @@ namespace Perspex.Cairo.Media
         {
             this.SetBrush(pen.Brush);
             this.context.LineWidth = pen.Thickness;
+            
         }
     }
 }

Cairo/Perspex.Cairo/Media/FormattedTextImpl.cs

@@ -20,6 +20,7 @@ namespace Perspex.Cairo.Media
             string fontFamily,
             double fontSize,
             FontStyle fontStyle,
+            TextAlignment textAlignment,
             FontWeight fontWeight)
         {
             var context = Locator.Current.GetService<Pango.Context>();
@@ -32,6 +33,8 @@ namespace Perspex.Cairo.Media
                 Style = (Pango.Style)fontStyle,
                 Weight = fontWeight.ToCairo()
             };
+
+            this.Layout.Alignment = textAlignment.ToCairo();
         }
 
         public Size Constraint
@@ -98,6 +101,12 @@ namespace Perspex.Cairo.Media
             int width;
             int height;
             this.Layout.GetPixelSize(out width, out height);
+        
+            if (this.Layout.Alignment == Pango.Alignment.Right)
+            {
+                return new Size(width, height);
+            }
+
             return new Size(width, height);
         }
 

Cairo/Perspex.Cairo/Media/Imaging/RenderTargetBitmapImpl.cs

@@ -12,7 +12,6 @@ namespace Perspex.Cairo.Media.Imaging
 
     public class RenderTargetBitmapImpl : BitmapImpl, IRenderTargetBitmapImpl
     {
-
         public RenderTargetBitmapImpl(
             Cairo.ImageSurface surface)
             : base(surface)

Cairo/Perspex.Cairo/Media/StreamGeometryContextImpl.cs

@@ -24,21 +24,17 @@ namespace Perspex.Cairo.Media
 
         public void ArcTo(Point point, Size size, double rotationAngle, bool isLargeArc, SweepDirection sweepDirection)
         {
-            // TODO: Implement
-            int i = 10;
             points.Add(point);
         }
 
         public void BeginFigure(Point startPoint, bool isFilled)
         {
-            System.Diagnostics.Debug.WriteLine("IS filled {0}", isFilled);
             this.impl.Operations.Enqueue(new BeginOp { Point = startPoint, IsFilled = isFilled });
             points.Add(startPoint);
         }
 
         public void BezierTo(Point point1, Point point2, Point point3)
         {
-            // TODO: Implement
             this.impl.Operations.Enqueue(new CurveToOp { Point = point1, Point2 = point2, Point3 = point3 });
             points.Add(point1);
             points.Add(point2);
@@ -63,6 +59,7 @@ namespace Perspex.Cairo.Media
                 maxX = System.Math.Max(p.X, maxX);
                 maxY = System.Math.Max(p.Y, maxY);
             }
+            
 
             var context = new Cairo.Context(new Cairo.ImageSurface(Cairo.Format.Argb32, (int)maxX, (int)maxY));
             var clone = new Queue<GeometryOp>(this.impl.Operations);
@@ -95,6 +92,7 @@ namespace Perspex.Cairo.Media
                 }
 
                 context.StrokePreserve();
+                context.FillPreserve();
             }
 
             var test = context.StrokeExtents();

Cairo/Perspex.Cairo/Perspex.Cairo.csproj

@@ -11,7 +11,8 @@
     <AssemblyName>Perspex.Cairo</AssemblyName>
     <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
     <FileAlignment>512</FileAlignment>
-    <NuGetPackageImportStamp>b122e795</NuGetPackageImportStamp>
+    <NuGetPackageImportStamp>
+    </NuGetPackageImportStamp>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DebugSymbols>true</DebugSymbols>
@@ -43,9 +44,9 @@
     <Reference Include="pango-sharp, Version=2.12.0.0, Culture=neutral, PublicKeyToken=35e10195dab3c99f, processorArchitecture=MSIL">
       <Package>gtk-sharp-2.0</Package>
     </Reference>
-    <Reference Include="Splat, Version=1.6.1.0, Culture=neutral, processorArchitecture=MSIL">
+    <Reference Include="Splat, Version=1.6.2.0, Culture=neutral, processorArchitecture=MSIL">
-      <SpecificVersion>False</SpecificVersion>
+      <HintPath>..\..\packages\Splat.1.6.2\lib\Net45\Splat.dll</HintPath>
-      <HintPath>..\..\packages\Splat.1.6.1\lib\Net45\Splat.dll</HintPath>
+      <Private>True</Private>
     </Reference>
     <Reference Include="System" />
     <Reference Include="System.Core" />
@@ -95,13 +96,6 @@
     <None Include="packages.config" />
   </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
-  <Import Project="..\..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets" Condition="Exists('..\..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets')" />
-  <Target Name="EnsureNuGetPackageBuildImports" BeforeTargets="PrepareForBuild">
-    <PropertyGroup>
-      <ErrorText>This project references NuGet package(s) that are missing on this computer. Enable NuGet Package Restore to download them.  For more information, see http://go.microsoft.com/fwlink/?LinkID=322105. The missing file is {0}.</ErrorText>
-    </PropertyGroup>
-    <Error Condition="!Exists('..\..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets')" Text="$([System.String]::Format('$(ErrorText)', '..\..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets'))" />
-  </Target>
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.
   <Target Name="BeforeBuild">

Cairo/Perspex.Cairo/Renderer.cs

@@ -20,6 +20,8 @@ namespace Perspex.Cairo
     /// </summary>
     public class Renderer : RendererBase
     {
+        private ImageSurface surface;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="Renderer"/> class.
         /// </summary>
@@ -29,8 +31,7 @@ namespace Perspex.Cairo
         public Renderer(IPlatformHandle handle, double width, double height)
         {
         }
-
+        
-        private ImageSurface surface;
         public Renderer(ImageSurface surface)
         {
             this.surface = surface;

Cairo/Perspex.Cairo/packages.config

@@ -1,7 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="Rx-Core" version="2.2.5" targetFramework="net45" />
+  <package id="Rx-Core" version="2.2.5" targetFramework="net45" userInstalled="true" />
-  <package id="Rx-Interfaces" version="2.2.5" targetFramework="net45" />
+  <package id="Rx-Interfaces" version="2.2.5" targetFramework="net45" userInstalled="true" />
-  <package id="Splat" version="1.6.1" targetFramework="net45" />
+  <package id="Splat" version="1.6.2" targetFramework="net45" userInstalled="true" />
-  <package id="StyleCop.MSBuild" version="4.7.49.0" targetFramework="net45" developmentDependency="true" />
 </packages>

Gtk/Perspex.Gtk/Input/GtkKeyboardDevice.cs

@@ -22,7 +22,7 @@ namespace Perspex.Gtk
         {
         }
 
-        public static GtkKeyboardDevice Instance
+        public static new GtkKeyboardDevice Instance
         {
             get { return instance; }
         }

Gtk/Perspex.Gtk/Input/GtkMouseDevice.cs

@@ -22,7 +22,7 @@ namespace Perspex.Gtk
         {
         }
 
-        public static GtkMouseDevice Instance
+        public static new GtkMouseDevice Instance
         {
             get { return instance; }
         }
@@ -31,10 +31,5 @@ namespace Perspex.Gtk
         {
             this.clientPosition = p;
         }
-
-        protected override Point GetClientPosition()
-        {
-            return this.clientPosition;
-        }
     }
 }

Gtk/Perspex.Gtk/Perspex.Gtk.csproj

@@ -8,7 +8,8 @@
     <RootNamespace>Perspex.Gtk</RootNamespace>
     <AssemblyName>Perspex.Gtk</AssemblyName>
     <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
-    <NuGetPackageImportStamp>ad245ae8</NuGetPackageImportStamp>
+    <NuGetPackageImportStamp>
+    </NuGetPackageImportStamp>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DebugSymbols>true</DebugSymbols>
@@ -29,9 +30,9 @@
     <ConsolePause>false</ConsolePause>
   </PropertyGroup>
   <ItemGroup>
-    <Reference Include="Splat, Version=1.6.1.0, Culture=neutral, processorArchitecture=MSIL">
+    <Reference Include="Splat, Version=1.6.2.0, Culture=neutral, processorArchitecture=MSIL">
-      <SpecificVersion>False</SpecificVersion>
+      <HintPath>..\..\packages\Splat.1.6.2\lib\Net45\Splat.dll</HintPath>
-      <HintPath>..\..\packages\Splat.1.6.1\lib\Net45\Splat.dll</HintPath>
+      <Private>True</Private>
     </Reference>
     <Reference Include="System" />
     <Reference Include="gtk-sharp, Version=2.12.0.0, Culture=neutral, PublicKeyToken=35e10195dab3c99f">
@@ -103,11 +104,4 @@
     <None Include="packages.config" />
   </ItemGroup>
   <ItemGroup />
-  <Import Project="..\..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets" Condition="Exists('..\..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets')" />
-  <Target Name="EnsureNuGetPackageBuildImports" BeforeTargets="PrepareForBuild">
-    <PropertyGroup>
-      <ErrorText>This project references NuGet package(s) that are missing on this computer. Enable NuGet Package Restore to download them.  For more information, see http://go.microsoft.com/fwlink/?LinkID=322105. The missing file is {0}.</ErrorText>
-    </PropertyGroup>
-    <Error Condition="!Exists('..\..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets')" Text="$([System.String]::Format('$(ErrorText)', '..\..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets'))" />
-  </Target>
 </Project>

Gtk/Perspex.Gtk/packages.config

@@ -1,8 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="Rx-Core" version="2.2.5" targetFramework="net45" />
+  <package id="Rx-Core" version="2.2.5" targetFramework="net45" userInstalled="true" />
-  <package id="Rx-Interfaces" version="2.2.5" targetFramework="net45" />
+  <package id="Rx-Interfaces" version="2.2.5" targetFramework="net45" userInstalled="true" />
-  <package id="Rx-Linq" version="2.2.5" targetFramework="net45" />
+  <package id="Rx-Linq" version="2.2.5" targetFramework="net45" userInstalled="true" />
-  <package id="Splat" version="1.6.1" targetFramework="net45" />
+  <package id="Splat" version="1.6.2" targetFramework="net45" userInstalled="true" />
-  <package id="StyleCop.MSBuild" version="4.7.49.0" targetFramework="net45" developmentDependency="true" />
 </packages>

Perspex-Mono.sln

@@ -1,7 +1,7 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio 14
-VisualStudioVersion = 14.0.22609.0
+VisualStudioVersion = 14.0.22823.1
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.Base", "Perspex.Base\Perspex.Base.csproj", "{B09B78D8-9B26-48B0-9149-D64A2F120F3F}"
 EndProject
@@ -53,7 +53,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = ".nuget", ".nuget", "{596AF7
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Tests", "Tests", "{C5A00AC3-B34C-4564-9BDD-2DA473EF4D8B}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.Cairo.RenderTests", "Tests\Perspex.RenderTests\Perspex.Cairo.RenderTests.csproj", "{DABFD304-D6A4-4752-8123-C2CCF7AC7831}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.Cairo.RenderTests", "Tests\Perspex.RenderTests\Perspex.Cairo.RenderTests.csproj", "{E106CF37-4066-4615-B684-172A6D30B058}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -141,10 +141,10 @@ Global
 		{D211E587-D8BC-45B9-95A4-F297C8FA5200}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{D211E587-D8BC-45B9-95A4-F297C8FA5200}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{D211E587-D8BC-45B9-95A4-F297C8FA5200}.Release|Any CPU.Build.0 = Release|Any CPU
-		{DABFD304-D6A4-4752-8123-C2CCF7AC7831}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{E106CF37-4066-4615-B684-172A6D30B058}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{DABFD304-D6A4-4752-8123-C2CCF7AC7831}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{E106CF37-4066-4615-B684-172A6D30B058}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{DABFD304-D6A4-4752-8123-C2CCF7AC7831}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{E106CF37-4066-4615-B684-172A6D30B058}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{DABFD304-D6A4-4752-8123-C2CCF7AC7831}.Release|Any CPU.Build.0 = Release|Any CPU
+		{E106CF37-4066-4615-B684-172A6D30B058}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -158,6 +158,6 @@ Global
 		{2905FF23-53FB-45E6-AA49-6AF47A172056} = {C5A00AC3-B34C-4564-9BDD-2DA473EF4D8B}
 		{415E048E-4611-4815-9CF2-D774E29079AC} = {2BAFBE53-7FA4-4BB9-976F-9AFCC4F9847D}
 		{DB070A10-BF39-4752-8456-86E9D5928478} = {C5A00AC3-B34C-4564-9BDD-2DA473EF4D8B}
-		{DABFD304-D6A4-4752-8123-C2CCF7AC7831} = {C5A00AC3-B34C-4564-9BDD-2DA473EF4D8B}
+		{E106CF37-4066-4615-B684-172A6D30B058} = {C5A00AC3-B34C-4564-9BDD-2DA473EF4D8B}
 	EndGlobalSection
 EndGlobal

Perspex-Windows.sln

@@ -1,161 +0,0 @@
-
-Microsoft Visual Studio Solution File, Format Version 12.00
-# Visual Studio 14
-VisualStudioVersion = 14.0.22609.0
-MinimumVisualStudioVersion = 10.0.40219.1
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.Win32", "Windows\Perspex.Win32\Perspex.Win32.csproj", "{811A76CF-1CF6-440F-963B-BBE31BD72A82}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "TestApplication", "TestApplication\TestApplication.csproj", "{E3A1060B-50D0-44E8-88B6-F44EF2E5BD72}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.Direct2D1", "Windows\Perspex.Direct2D1\Perspex.Direct2D1.csproj", "{3E908F67-5543-4879-A1DC-08EACE79B3CD}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.Base", "Perspex.Base\Perspex.Base.csproj", "{B09B78D8-9B26-48B0-9149-D64A2F120F3F}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.SceneGraph", "Perspex.SceneGraph\Perspex.SceneGraph.csproj", "{EB582467-6ABB-43A1-B052-E981BA910E3A}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.Layout", "Perspex.Layout\Perspex.Layout.csproj", "{42472427-4774-4C81-8AFF-9F27B8E31721}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Windows", "Windows", "{B39A8919-9F95-48FE-AD7B-76E08B509888}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.Input", "Perspex.Input\Perspex.Input.csproj", "{62024B2D-53EB-4638-B26B-85EEAA54866E}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.Interactivity", "Perspex.Interactivity\Perspex.Interactivity.csproj", "{6B0ED19D-A08B-461C-A9D9-A9EE40B0C06B}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.Controls", "Perspex.Controls\Perspex.Controls.csproj", "{D2221C82-4A25-4583-9B43-D791E3F6820C}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.Styling", "Perspex.Styling\Perspex.Styling.csproj", "{F1BAA01A-F176-4C6A-B39D-5B40BB1B148F}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.Styling.UnitTests", "Tests\Perspex.Styling.UnitTests\Perspex.Styling.UnitTests.csproj", "{47ECDF59-DEF8-4C53-87B1-2098A3429059}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.Controls.UnitTests", "Tests\Perspex.Controls.UnitTests\Perspex.Controls.UnitTests.csproj", "{5CCB5571-7C30-4E7D-967D-0E2158EBD91F}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.Themes.Default", "Perspex.Themes.Default\Perspex.Themes.Default.csproj", "{3E10A5FA-E8DA-48B1-AD44-6A5B6CB7750F}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.SceneGraph.UnitTests", "Tests\Perspex.SceneGraph.UnitTests\Perspex.SceneGraph.UnitTests.csproj", "{76716382-3159-460E-BDA6-C5715CF606D7}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.Application", "Perspex.Application\Perspex.Application.csproj", "{799A7BB5-3C2C-48B6-85A7-406A12C420DA}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Perspex.Diagnostics", "Perspex.Diagnostics\Perspex.Diagnostics.csproj", "{7062AE20-5DCC-4442-9645-8195BDECE63E}"
-EndProject
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Perspex.Animation/Animatable.cs

@@ -9,10 +9,22 @@ namespace Perspex.Animation
     using System.Linq;
     using System.Reactive.Linq;
 
+    /// <summary>
+    /// Base class for control which can have property transitions.
+    /// </summary>
     public class Animatable : PerspexObject
     {
+        /// <summary>
+        /// The property transitions for the control.
+        /// </summary>
         private PropertyTransitions propertyTransitions;
 
+        /// <summary>
+        /// Gets or sets the property transitions for the control.
+        /// </summary>
+        /// <value>
+        /// The property transitions for the control.
+        /// </value>
         public PropertyTransitions PropertyTransitions
         {
             get
@@ -31,6 +43,11 @@ namespace Perspex.Animation
             }
         }
 
+        /// <summary>
+        /// Reacts to a change in a <see cref="PerspexProperty"/> value in order to animate the
+        /// change if a <see cref="PropertyTransition"/> is set for the property..
+        /// </summary>
+        /// <param name="e">The event args.</param>
         protected override void OnPropertyChanged(PerspexPropertyChangedEventArgs e)
         {
             if (e.Priority != BindingPriority.Animation && this.propertyTransitions != null)

Perspex.Animation/Animate.cs

@@ -28,7 +28,7 @@ namespace Perspex.Animation
         private static readonly TimeSpan Tick = TimeSpan.FromSeconds(1.0 / FramesPerSecond);
 
         /// <summary>
-        /// Initializes the static class.
+        /// Initializes static members of the <see cref="Animate"/> class.
         /// </summary>
         static Animate()
         {
@@ -43,6 +43,9 @@ namespace Perspex.Animation
         /// <summary>
         /// The stopwatch used to track time.
         /// </summary>
+        /// <value>
+        /// The stopwatch used to track time.
+        /// </value>
         public static Stopwatch Stopwatch
         {
             get;
@@ -53,10 +56,13 @@ namespace Perspex.Animation
         /// Gets the animation timer.
         /// </summary>
         /// <remarks>
-        /// The animation timer ticks <see cref="FramesPerSecond"/> times per second. The 
+        /// The animation timer ticks <see cref="FramesPerSecond"/> times per second. The
-        /// parameter passed to a subsciber is the time span since the animation system was 
+        /// parameter passed to a subsciber is the time span since the animation system was
         /// initialized.
         /// </remarks>
+        /// <value>
+        /// The animation timer.
+        /// </value>
         public static IObservable<TimeSpan> Timer
         {
             get;
@@ -78,7 +84,7 @@ namespace Perspex.Animation
         public static IObservable<double> GetTimer(TimeSpan duration)
         {
             var startTime = Stopwatch.Elapsed.Ticks;
-            var endTime = (startTime + duration.Ticks);
+            var endTime = startTime + duration.Ticks;
             return Timer
                 .TakeWhile(x => x.Ticks < endTime)
                 .Select(x => (x.Ticks - startTime) / (double)duration.Ticks)
@@ -89,15 +95,14 @@ namespace Perspex.Animation
         /// <summary>
         /// Animates a <see cref="PerspexProperty"/>.
         /// </summary>
-        /// <typeparam name="T">The property type.</typeparam>
         /// <param name="target">The target object.</param>
         /// <param name="property">The target property.</param>
         /// <param name="start">The value of the property at the start of the animation.</param>
         /// <param name="finish">The value of the property at the end of the animation.</param>
         /// <param name="easing">The easing function to use.</param>
         /// <param name="duration">The duration of the animation.</param>
-        /// <returns>An <see cref="IDisposable"/> that can be used to stop the animation.</returns>
+        /// <returns>An <see cref="Animation"/> that can be used to track or stop the animation.</returns>
-        public static IDisposable Property(
+        public static Animation Property(
             PerspexObject target,
             PerspexProperty property,
             object start,
@@ -106,7 +111,7 @@ namespace Perspex.Animation
             TimeSpan duration)
         {
             var o = GetTimer(duration).Select(progress => easing.Ease(progress, start, finish));
-            return target.Bind(property, o, BindingPriority.Animation);
+            return new Animation(o, target.Bind(property, o, BindingPriority.Animation));
         }
 
         /// <summary>
@@ -119,17 +124,17 @@ namespace Perspex.Animation
         /// <param name="finish">The value of the property at the end of the animation.</param>
         /// <param name="easing">The easing function to use.</param>
         /// <param name="duration">The duration of the animation.</param>
-        /// <returns>An <see cref="IDisposable"/> that can be used to stop the animation.</returns>
+        /// <returns>An <see cref="Animation"/> that can be used to track or stop the animation.</returns>
-        public static IDisposable Property<T>(
+        public static Animation<T> Property<T>(
             PerspexObject target,
-            PerspexProperty<T> property, 
+            PerspexProperty<T> property,
-            T start, 
+            T start,
             T finish,
             IEasing<T> easing,
             TimeSpan duration)
         {
             var o = GetTimer(duration).Select(progress => easing.Ease(progress, start, finish));
-            return target.Bind(property, o, BindingPriority.Animation);
+            return new Animation<T>(o, target.Bind(property, o, BindingPriority.Animation));
         }
     }
 }

Perspex.Animation/Animation.cs

@@ -0,0 +1,58 @@
+// -----------------------------------------------------------------------
+// <copyright file="Animation.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Animation
+{
+    using System;
+
+    /// <summary>
+    /// Tracks the progress of an animation.
+    /// </summary>
+    public class Animation : IObservable<object>, IDisposable
+    {
+        /// <summary>
+        /// The animation being tracked.
+        /// </summary>
+        private IObservable<object> inner;
+
+        /// <summary>
+        /// The disposable used to cancel the animation.
+        /// </summary>
+        private IDisposable subscription;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Animation"/> class.
+        /// </summary>
+        /// <param name="inner">The animation observable being tracked.</param>
+        /// <param name="subscription">A disposable used to cancel the animation.</param>
+        public Animation(IObservable<object> inner, IDisposable subscription)
+        {
+            this.inner = inner;
+            this.subscription = subscription;
+        }
+
+        /// <summary>
+        /// Cancels the animation.
+        /// </summary>
+        public void Dispose()
+        {
+            this.subscription.Dispose();
+        }
+
+        /// <summary>
+        /// Notifies the provider that an observer is to receive notifications.
+        /// </summary>
+        /// <param name="observer">The observer.</param>
+        /// <returns>
+        /// A reference to an interface that allows observers to stop receiving notifications
+        /// before the provider has finished sending them.
+        /// </returns>
+        public IDisposable Subscribe(IObserver<object> observer)
+        {
+            return this.inner.Subscribe(observer);
+        }
+    }
+}

Perspex.Animation/AnimationExtensions.cs

@@ -1,5 +1,5 @@
 // -----------------------------------------------------------------------
-// <copyright file="PropertyTransition.cs" company="Steven Kirk">
+// <copyright file="AnimationExtensions.cs" company="Steven Kirk">
 // Copyright 2014 MIT Licence. See licence.md for more information.
 // </copyright>
 // -----------------------------------------------------------------------
@@ -8,21 +8,41 @@ namespace Perspex.Animation
 {
     using System;
 
+    /// <summary>
+    /// Defines animation extension methods.
+    /// </summary>
     public static class AnimationExtensions
     {
+        /// <summary>
+        /// Returns a new <see cref="PropertyTransition"/> for the specified
+        /// <see cref="PerspexProperty"/> using linear easing.
+        /// </summary>
+        /// <typeparam name="T">The type of the <see cref="PerspexProperty"/>.</typeparam>
+        /// <param name="property">The property to animate.</param>
+        /// <param name="milliseconds">The animation duration in milliseconds.</param>
+        /// <returns>
+        /// A <see cref="PropertyTransition"/> that can be added to the
+        /// <see cref="Animatable.PropertyTransitions"/> collection.
+        /// </returns>
         public static PropertyTransition Transition<T>(this PerspexProperty<T> property, int milliseconds)
         {
             return Transition(property, TimeSpan.FromMilliseconds(milliseconds));
         }
 
+        /// <summary>
+        /// Returns a new <see cref="PropertyTransition"/> for the specified
+        /// <see cref="PerspexProperty"/> using linear easing.
+        /// </summary>
+        /// <typeparam name="T">The type of the <see cref="PerspexProperty"/>.</typeparam>
+        /// <param name="property">The property to animate.</param>
+        /// <param name="duration">The animation duration.</param>
+        /// <returns>
+        /// A <see cref="PropertyTransition"/> that can be added to the
+        /// <see cref="Animatable.PropertyTransitions"/> collection.
+        /// </returns>
         public static PropertyTransition Transition<T>(this PerspexProperty<T> property, TimeSpan duration)
         {
-            return new PropertyTransition
+            return new PropertyTransition(property, duration, LinearEasing.For<T>());
-            {
-                Property = property,
-                Duration = duration,
-                Easing = LinearEasing.For<T>(),
-            };
         }
     }
 }

Perspex.Animation/Animation`1.cs

@@ -0,0 +1,59 @@
+// -----------------------------------------------------------------------
+// <copyright file="Animation`1.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Animation
+{
+    using System;
+
+    /// <summary>
+    /// Tracks the progress of an animation.
+    /// </summary>
+    /// <typeparam name="T">The type of the value being animated./</typeparam>
+    public class Animation<T> : IObservable<T>, IDisposable
+    {
+        /// <summary>
+        /// The animation being tracked.
+        /// </summary>
+        private IObservable<T> inner;
+
+        /// <summary>
+        /// The disposable used to cancel the animation.
+        /// </summary>
+        private IDisposable subscription;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Animation{T}"/> class.
+        /// </summary>
+        /// <param name="inner">The animation observable being tracked.</param>
+        /// <param name="subscription">A disposable used to cancel the animation.</param>
+        public Animation(IObservable<T> inner, IDisposable subscription)
+        {
+            this.inner = inner;
+            this.subscription = subscription;
+        }
+
+        /// <summary>
+        /// Cancels the animation.
+        /// </summary>
+        public void Dispose()
+        {
+            this.subscription.Dispose();
+        }
+
+        /// <summary>
+        /// Notifies the provider that an observer is to receive notifications.
+        /// </summary>
+        /// <param name="observer">The observer.</param>
+        /// <returns>
+        /// A reference to an interface that allows observers to stop receiving notifications
+        /// before the provider has finished sending them.
+        /// </returns>
+        public IDisposable Subscribe(IObserver<T> observer)
+        {
+            return this.inner.Subscribe(observer);
+        }
+    }
+}

Perspex.Animation/IEasing.cs

@@ -1,18 +1,26 @@
 // -----------------------------------------------------------------------
-// <copyright file="PropertyTransition.cs" company="Steven Kirk">
+// <copyright file="IEasing.cs" company="Steven Kirk">
 // Copyright 2014 MIT Licence. See licence.md for more information.
 // </copyright>
 // -----------------------------------------------------------------------
 
 namespace Perspex.Animation
 {
+    /// <summary>
+    /// Defines the interface for easing functions.
+    /// </summary>
     public interface IEasing
     {
+        /// <summary>
+        /// Returns the value of the transition for the specified progress.
+        /// </summary>
+        /// <param name="progress">The progress of the transition, from 0 to 1.</param>
+        /// <param name="start">The start value of the transition.</param>
+        /// <param name="finish">The end value of the transition.</param>
+        /// <returns>
+        /// A value between <paramref name="start"/> and <paramref name="finish"/> as determined
+        /// by <paramref name="progress"/>.
+        /// </returns>
         object Ease(double progress, object start, object finish);
     }
-
-    public interface IEasing<T> : IEasing
-    {
-        T Ease(double progress, T start, T finish);
-    }
 }

Perspex.Animation/IEasing`1.cs

@@ -0,0 +1,27 @@
+// -----------------------------------------------------------------------
+// <copyright file="IEasing`1.cs" company="Steven Kirk">
+// Copyright 2014 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Animation
+{
+    /// <summary>
+    /// Defines the interface for easing functions.
+    /// </summary>
+    /// <typeparam name="T">The type of the property being transitioned.</typeparam>
+    public interface IEasing<T> : IEasing
+    {
+        /// <summary>
+        /// Returns the value of the transition for the specified progress.
+        /// </summary>
+        /// <param name="progress">The progress of the transition, from 0 to 1.</param>
+        /// <param name="start">The start value of the transition.</param>
+        /// <param name="finish">The end value of the transition.</param>
+        /// <returns>
+        /// A value between <paramref name="start"/> and <paramref name="finish"/> as determined
+        /// by <paramref name="progress"/>.
+        /// </returns>
+        T Ease(double progress, T start, T finish);
+    }
+}

Perspex.Animation/LinearDoubleEasing.cs

@@ -1,21 +1,42 @@
 // -----------------------------------------------------------------------
-// <copyright file="PropertyTransition.cs" company="Steven Kirk">
+// <copyright file="LinearDoubleEasing.cs" company="Steven Kirk">
 // Copyright 2014 MIT Licence. See licence.md for more information.
 // </copyright>
 // -----------------------------------------------------------------------
 
 namespace Perspex.Animation
 {
-    using System;
+    /// <summary>
-
+    /// Linearly eases a double value.
+    /// </summary>
     public class LinearDoubleEasing : IEasing<double>
     {
+        /// <summary>
+        /// Returns the value of the transition for the specified progress.
+        /// </summary>
+        /// <param name="progress">The progress of the transition, from 0 to 1.</param>
+        /// <param name="start">The start value of the transition.</param>
+        /// <param name="finish">The end value of the transition.</param>
+        /// <returns>
+        /// A value between <paramref name="start"/> and <paramref name="finish"/> as determined
+        /// by <paramref name="progress"/>.
+        /// </returns>
         public double Ease(double progress, double start, double finish)
         {
             return ((finish - start) * progress) + start;
         }
 
-        public object Ease(double progress, object start, object finish)
+        /// <summary>
+        /// Returns the value of the transition for the specified progress.
+        /// </summary>
+        /// <param name="progress">The progress of the transition, from 0 to 1.</param>
+        /// <param name="start">The start value of the transition.</param>
+        /// <param name="finish">The end value of the transition.</param>
+        /// <returns>
+        /// A value between <paramref name="start"/> and <paramref name="finish"/> as determined
+        /// by <paramref name="progress"/>.
+        /// </returns>
+        object IEasing.Ease(double progress, object start, object finish)
         {
             return this.Ease(progress, (double)start, (double)finish);
         }

Perspex.Animation/LinearEasing.cs

@@ -1,5 +1,5 @@
 // -----------------------------------------------------------------------
-// <copyright file="PropertyTransition.cs" company="Steven Kirk">
+// <copyright file="LinearEasing.cs" company="Steven Kirk">
 // Copyright 2014 MIT Licence. See licence.md for more information.
 // </copyright>
 // -----------------------------------------------------------------------
@@ -8,13 +8,25 @@ namespace Perspex.Animation
 {
     using System;
 
+    /// <summary>
+    /// Returns a linear <see cref="IEasing"/> for the specified type.
+    /// </summary>
+    /// <remarks>
+    /// Unfortunately this class is needed as there's no way to create a true generic easing
+    /// function at compile time, as mathematical operators don't have an interface.
+    /// </remarks>
     public static class LinearEasing
     {
-        public static LinearDoubleEasing For<T>()
+        /// <summary>
+        /// A linear easing function for the specified type.
+        /// </summary>
+        /// <typeparam name="T">The type.</typeparam>
+        /// <returns>An easing function.</returns>
+        public static IEasing<T> For<T>()
         {
             if (typeof(T) == typeof(double))
             {
-                return new LinearDoubleEasing();
+                return (IEasing<T>)new LinearDoubleEasing();
             }
             else
             {

Perspex.Animation/Perspex.Animation.csproj

@@ -41,9 +41,12 @@
     </ProjectReference>
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Animation`1.cs" />
+    <Compile Include="Animation.cs" />
     <Compile Include="Animate.cs" />
     <Compile Include="Animatable.cs" />
     <Compile Include="AnimationExtensions.cs" />
+    <Compile Include="IEasing`1.cs" />
     <Compile Include="LinearEasing.cs" />
     <Compile Include="LinearDoubleEasing.cs" />
     <Compile Include="IEasing.cs" />
@@ -68,6 +71,9 @@
   <ItemGroup>
     <None Include="packages.config" />
   </ItemGroup>
+  <ItemGroup>
+    <Analyzer Include="..\packages\StyleCop.Analyzers.1.0.0-alpha008\tools\analyzers\C#\StyleCop.Analyzers.dll" />
+  </ItemGroup>
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\Portable\$(TargetFrameworkVersion)\Microsoft.Portable.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.

Perspex.Animation/Properties/AssemblyInfo.cs

@@ -1,9 +1,15 @@
-using System.Resources;
+// -----------------------------------------------------------------------
+// <copyright file="AssemblyInfo.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+using System.Resources;
 using System.Reflection;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
-// General Information about an assembly is controlled through the following 
+// General Information about an assembly is controlled through the following
 // set of attributes. Change these attribute values to modify the information
 // associated with an assembly.
 [assembly: AssemblyTitle("Perspex.Animation")]
@@ -19,11 +25,11 @@ using System.Runtime.InteropServices;
 // Version information for an assembly consists of the following four values:
 //
 //      Major Version
-//      Minor Version 
+//      Minor Version
 //      Build Number
 //      Revision
 //
-// You can specify all the values or you can default the Build and Revision Numbers 
+// You can specify all the values or you can default the Build and Revision Numbers
 // by using the '*' as shown below:
 // [assembly: AssemblyVersion("1.0.*")]
 [assembly: AssemblyVersion("1.0.0.0")]

Perspex.Animation/PropertyTransition.cs

@@ -8,12 +8,46 @@ namespace Perspex.Animation
 {
     using System;
 
+    /// <summary>
+    /// Defines how a property should be animated using a transition.
+    /// </summary>
     public class PropertyTransition
     {
-        public PerspexProperty Property { get; set; }
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PropertyTransition"/> class.
+        /// </summary>
+        /// <param name="property">The property to be animated/</param>
+        /// <param name="duration">The duration of the animation.</param>
+        /// <param name="easing">The easing function to use.</param>
+        public PropertyTransition(PerspexProperty property, TimeSpan duration, IEasing easing)
+        {
+            this.Property = property;
+            this.Duration = duration;
+            this.Easing = easing;
+        }
 
-        public TimeSpan Duration { get; set; }
+        /// <summary>
+        /// Gets the property to be animated.
+        /// </summary>
+        /// <value>
+        /// The property to be animated.
+        /// </value>
+        public PerspexProperty Property { get; }
 
-        public IEasing Easing { get; set; }
+        /// <summary>
+        /// Gets the duration of the animation.
+        /// </summary>
+        /// <value>
+        /// The duration of the animation.
+        /// </value>
+        public TimeSpan Duration { get; }
+
+        /// <summary>
+        /// Gets the easing function used.
+        /// </summary>
+        /// <value>
+        /// The easing function.
+        /// </value>
+        public IEasing Easing { get; }
     }
 }

Perspex.Animation/PropertyTransitions.cs

@@ -4,12 +4,13 @@
 // </copyright>
 // -----------------------------------------------------------------------
 
-using Perspex.Collections;
-
 namespace Perspex.Animation
 {
     using Perspex.Collections;
 
+    /// <summary>
+    /// A collection of <see cref="PropertyTransition"/> definitions.
+    /// </summary>
     public class PropertyTransitions : PerspexList<PropertyTransition>
     {
     }

Perspex.Animation/packages.config

@@ -1,8 +1,9 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="Rx-Core" version="2.2.5" targetFramework="portable-net45+win" />
+  <package id="Rx-Core" version="2.2.5" targetFramework="portable-net45+win8" userInstalled="true" />
-  <package id="Rx-Interfaces" version="2.2.5" targetFramework="portable-net45+win" />
+  <package id="Rx-Interfaces" version="2.2.5" targetFramework="portable-net45+win8" userInstalled="true" />
-  <package id="Rx-Linq" version="2.2.5" targetFramework="portable-net45+win" />
+  <package id="Rx-Linq" version="2.2.5" targetFramework="portable-net45+win8" userInstalled="true" />
-  <package id="Rx-Main" version="2.2.5" targetFramework="portable-net45+win" />
+  <package id="Rx-Main" version="2.2.5" targetFramework="portable-net45+win8" userInstalled="true" />
-  <package id="Rx-PlatformServices" version="2.2.5" targetFramework="portable-net45+win" />
+  <package id="Rx-PlatformServices" version="2.2.5" targetFramework="portable-net45+win8" userInstalled="true" />
+  <package id="StyleCop.Analyzers" version="1.0.0-alpha008" targetFramework="portable45-net45+win8" userInstalled="true" />
 </packages>

Perspex.Application/Application.cs

@@ -16,12 +16,36 @@ namespace Perspex
     using Perspex.Threading;
     using Splat;
 
+    /// <summary>
+    /// Encapsulates a Perspex application.
+    /// </summary>
+    /// <remarks>
+    /// The <see cref="Application"/> class encapsulates Perspex application-specific
+    /// functionality, including:
+    /// - A global set of <see cref="DataTemplates"/>.
+    /// - A global set of <see cref="Styles"/>.
+    /// - A <see cref="FocusManager"/>.
+    /// - An <see cref="InputManager"/>.
+    /// - Registers services needed by the rest of Perspex in the <see cref="RegisterServices"/>
+    /// method.
+    /// - Tracks the lifetime of the application.
+    /// </remarks>
     public class Application : IGlobalDataTemplates, IGlobalStyles
     {
+        /// <summary>
+        /// The application-global data templates.
+        /// </summary>
         private DataTemplates dataTemplates;
 
+        /// <summary>
+        /// The styler that will be used to apply styles to controls.
+        /// </summary>
         private Styler styler = new Styler();
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Application"/> class.
+        /// </summary>
+        /// <param name="theme">The theme to use.</param>
         public Application(Styles theme)
         {
             if (Current != null)
@@ -34,12 +58,24 @@ namespace Perspex
             this.RegisterServices();
         }
 
+        /// <summary>
+        /// Gets the current instance of the <see cref="Application"/> class.
+        /// </summary>
+        /// <value>
+        /// The current instance of the <see cref="Application"/> class.
+        /// </value>
         public static Application Current
         {
             get;
             private set;
         }
 
+        /// <summary>
+        /// Gets or sets the application's global data templates.
+        /// </summary>
+        /// <value>
+        /// The application's global data templates.
+        /// </value>
         public DataTemplates DataTemplates
         {
             get
@@ -58,30 +94,49 @@ namespace Perspex
             }
         }
 
+        /// <summary>
+        /// Gets the application's focus manager.
+        /// </summary>
+        /// <value>
+        /// The application's focus manager.
+        /// </value>
         public IFocusManager FocusManager
         {
             get;
             private set;
         }
 
+        /// <summary>
+        /// Gets the application's input manager.
+        /// </summary>
+        /// <value>
+        /// The application's input manager.
+        /// </value>
         public InputManager InputManager
         {
             get;
             private set;
         }
 
-        public KeyboardNavigation KeyboardNavigation
+        /// <summary>
-        {
+        /// Gets the application's global styles.
-            get;
+        /// </summary>
-            private set;
+        /// <value>
-        }
+        /// The application's global styles.
-
+        /// </value>
+        /// <remarks>
+        /// Global styles apply to all windows in the application.
+        /// </remarks>
         public Styles Styles
         {
             get;
             private set;
         }
 
+        /// <summary>
+        /// Runs the application's main loop until the <see cref="ICloseable"/> is closed.
+        /// </summary>
+        /// <param name="closable">The closable to track</param>
         public void Run(ICloseable closable)
         {
             var source = new CancellationTokenSource();
@@ -89,19 +144,21 @@ namespace Perspex
             Dispatcher.UIThread.MainLoop(source.Token);
         }
 
+        /// <summary>
+        /// Register's the services needed by Perspex.
+        /// </summary>
         protected virtual void RegisterServices()
         {
             this.FocusManager = new FocusManager();
             this.InputManager = new InputManager();
-            this.KeyboardNavigation = new KeyboardNavigation();
 
+            Locator.CurrentMutable.Register(() => new AccessKeyHandler(), typeof(IAccessKeyHandler));
             Locator.CurrentMutable.Register(() => this, typeof(IGlobalDataTemplates));
             Locator.CurrentMutable.Register(() => this, typeof(IGlobalStyles));
             Locator.CurrentMutable.Register(() => this.FocusManager, typeof(IFocusManager));
             Locator.CurrentMutable.Register(() => this.InputManager, typeof(IInputManager));
-            Locator.CurrentMutable.Register(() => this.KeyboardNavigation, typeof(IKeyboardNavigation));
+            Locator.CurrentMutable.Register(() => new KeyboardNavigationHandler(), typeof(IKeyboardNavigationHandler));
             Locator.CurrentMutable.Register(() => this.styler, typeof(IStyler));
-
             Locator.CurrentMutable.Register(() => new LayoutManager(), typeof(ILayoutManager));
             Locator.CurrentMutable.Register(() => new RenderManager(), typeof(IRenderManager));
         }

Perspex.Application/Perspex.Application.csproj

@@ -15,7 +15,8 @@
     <ProjectTypeGuids>{786C830F-07A1-408B-BD7F-6EE04809D6DB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
     <TargetFrameworkProfile>Profile7</TargetFrameworkProfile>
     <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
-    <NuGetPackageImportStamp>088bcbce</NuGetPackageImportStamp>
+    <NuGetPackageImportStamp>
+    </NuGetPackageImportStamp>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DebugSymbols>true</DebugSymbols>
@@ -70,8 +71,9 @@
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>
   <ItemGroup>
-    <Reference Include="Splat">
+    <Reference Include="Splat, Version=1.6.2.0, Culture=neutral, processorArchitecture=MSIL">
-      <HintPath>..\packages\Splat.1.6.1\lib\Portable-net45+win+wpa81+wp80\Splat.dll</HintPath>
+      <HintPath>..\packages\Splat.1.6.2\lib\Portable-net45+win+wpa81+wp80\Splat.dll</HintPath>
+      <Private>True</Private>
     </Reference>
     <Reference Include="System.Reactive.Core">
       <HintPath>..\packages\Rx-Core.2.2.5\lib\portable-windows8+net45+wp8\System.Reactive.Core.dll</HintPath>
@@ -90,14 +92,10 @@
     <None Include="app.config" />
     <None Include="packages.config" />
   </ItemGroup>
+  <ItemGroup>
+    <Analyzer Include="..\packages\StyleCop.Analyzers.1.0.0-alpha008\tools\analyzers\C#\StyleCop.Analyzers.dll" />
+  </ItemGroup>
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\Portable\$(TargetFrameworkVersion)\Microsoft.Portable.CSharp.targets" />
-  <Import Project="..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets" Condition="Exists('..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets')" />
-  <Target Name="EnsureNuGetPackageBuildImports" BeforeTargets="PrepareForBuild">
-    <PropertyGroup>
-      <ErrorText>This project references NuGet package(s) that are missing on this computer. Enable NuGet Package Restore to download them.  For more information, see http://go.microsoft.com/fwlink/?LinkID=322105. The missing file is {0}.</ErrorText>
-    </PropertyGroup>
-    <Error Condition="!Exists('..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets')" Text="$([System.String]::Format('$(ErrorText)', '..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets'))" />
-  </Target>
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.
   <Target Name="BeforeBuild">

Perspex.Application/Properties/AssemblyInfo.cs

@@ -7,7 +7,7 @@
 using System.Reflection;
 using System.Resources;
 
-// General Information about an assembly is controlled through the following 
+// General Information about an assembly is controlled through the following
 // set of attributes. Change these attribute values to modify the information
 // associated with an assembly.
 [assembly: AssemblyTitle("Perspex.Application")]
@@ -23,11 +23,11 @@ using System.Resources;
 // Version information for an assembly consists of the following four values:
 //
 //      Major Version
-//      Minor Version 
+//      Minor Version
 //      Build Number
 //      Revision
 //
-// You can specify all the values or you can default the Build and Revision Numbers 
+// You can specify all the values or you can default the Build and Revision Numbers
 // by using the '*' as shown below:
 // [assembly: AssemblyVersion("1.0.*")]
 [assembly: AssemblyVersion("1.0.0.0")]

Perspex.Application/packages.config

@@ -1,10 +1,10 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="Rx-Core" version="2.2.5" targetFramework="portable-net45+win" />
+  <package id="Rx-Core" version="2.2.5" targetFramework="portable-net45+win8" userInstalled="true" />
-  <package id="Rx-Interfaces" version="2.2.5" targetFramework="portable-net45+win" />
+  <package id="Rx-Interfaces" version="2.2.5" targetFramework="portable-net45+win8" userInstalled="true" />
-  <package id="Rx-Linq" version="2.2.5" targetFramework="portable-net45+win" />
+  <package id="Rx-Linq" version="2.2.5" targetFramework="portable-net45+win8" userInstalled="true" />
-  <package id="Rx-Main" version="2.2.5" targetFramework="portable-net45+win" />
+  <package id="Rx-Main" version="2.2.5" targetFramework="portable-net45+win8" userInstalled="true" />
-  <package id="Rx-PlatformServices" version="2.2.5" targetFramework="portable-net45+win" />
+  <package id="Rx-PlatformServices" version="2.2.5" targetFramework="portable-net45+win8" userInstalled="true" />
-  <package id="Splat" version="1.6.1" targetFramework="portable-net45+win" />
+  <package id="Splat" version="1.6.2" targetFramework="portable45-net45+win8" userInstalled="true" />
-  <package id="StyleCop.MSBuild" version="4.7.49.0" targetFramework="portable-net45+win" developmentDependency="true" />
+  <package id="StyleCop.Analyzers" version="1.0.0-alpha008" targetFramework="portable45-net45+win8" userInstalled="true" />
 </packages>

Perspex.Base/Binding.cs

@@ -7,7 +7,7 @@
 namespace Perspex
 {
     using System;
-    using System.Reactive.Linq;
+    using System.Reactive;
 
     public enum BindingMode
     {
@@ -18,7 +18,7 @@ namespace Perspex
         OneWayToSource,
     }
 
-    public class Binding : IObservable<object>
+    public class Binding : ObservableBase<object>, IDescription
     {
         public BindingMode Mode
         {
@@ -44,6 +44,8 @@ namespace Perspex
             set;
         }
 
+        public string Description => string.Format("{0}.{1}", this.Source?.GetType().Name, this.Property.Name);
+
         public static Binding operator !(Binding binding)
         {
             return binding.WithMode(BindingMode.TwoWay);
@@ -54,11 +56,6 @@ namespace Perspex
             return binding.WithMode(BindingMode.TwoWay);
         }
 
-        public IDisposable Subscribe(IObserver<object> observer)
-        {
-            return this.Source.GetObservable(this.Property).Subscribe(observer);
-        }
-
         public Binding WithMode(BindingMode mode)
         {
             this.Mode = mode;
@@ -70,5 +67,10 @@ namespace Perspex
             this.Priority = priority;
             return this;
         }
+
+        protected override IDisposable SubscribeCore(IObserver<object> observer)
+        {
+            return this.Source.GetObservable(this.Property).Subscribe(observer);
+        }
     }
 }

Perspex.Base/Collections/IPerspexReadOnlyList.cs

@@ -1,5 +1,5 @@
 // -----------------------------------------------------------------------
-// <copyright file="IReadOnlyPerspexList.cs" company="Steven Kirk">
+// <copyright file="IPerspexReadOnlyList.cs" company="Steven Kirk">
 // Copyright 2014 MIT Licence. See licence.md for more information.
 // </copyright>
 // -----------------------------------------------------------------------

Perspex.Base/Collections/PerspexList.cs

@@ -20,7 +20,7 @@ namespace Perspex.Collections
     /// <remarks>
     /// PerspexList is similar to <see cref="System.Collections.ObjectModel.ObservableCollection{T}"/>
     /// except that when the <see cref="Clear"/> method is called, it notifies with a
-    /// <see cref="NotifyCollectionChangedAction.Remove"/> action, passing the items that were 
+    /// <see cref="NotifyCollectionChangedAction.Remove"/> action, passing the items that were
     /// removed.
     /// </remarks>
     public class PerspexList<T> : IPerspexList<T>, INotifyCollectionChanged, INotifyPropertyChanged

Perspex.Base/Collections/PerspexReadOnlyListView.cs

@@ -29,17 +29,17 @@ namespace Perspex.Collections
             if (source != null)
             {
                 this.source.CollectionChanged += this.SourceCollectionChanged;
+                this.source.PropertyChanged += this.SourcePropertyChanged;
             }
         }
 
-        public T this[int index]
+        public event NotifyCollectionChangedEventHandler CollectionChanged;
-        {
+
-            get { return this.source[index]; }
+        public event PropertyChangedEventHandler PropertyChanged;
-        }
 
         public int Count
         {
-            get { return this.source.Count; }
+            get { return this.source?.Count ?? 0; }
         }
 
         public IPerspexReadOnlyList<T> Source
@@ -54,6 +54,7 @@ namespace Perspex.Collections
                 if (this.source != null)
                 {
                     this.source.CollectionChanged -= this.SourceCollectionChanged;
+                    this.source.PropertyChanged -= this.SourcePropertyChanged;
 
                     if (this.CollectionChanged != null)
                     {
@@ -70,12 +71,13 @@ namespace Perspex.Collections
                 if (this.source != null)
                 {
                     this.source.CollectionChanged += this.SourceCollectionChanged;
+                    this.source.PropertyChanged += this.SourcePropertyChanged;
 
                     if (this.CollectionChanged != null)
                     {
                         var ev = new NotifyCollectionChangedEventArgs(
                             NotifyCollectionChangedAction.Add,
-                            this.source,
+                            this.source.ToList(),
                             0);
                         this.CollectionChanged(this, ev);
                     }
@@ -83,13 +85,15 @@ namespace Perspex.Collections
             }
         }
 
-        public event NotifyCollectionChangedEventHandler CollectionChanged;
+        public T this[int index]
-
+        {
-        public event PropertyChangedEventHandler PropertyChanged;
+            get { return this.source[index]; }
+        }
 
         public void Dispose()
         {
             this.source.CollectionChanged -= this.SourceCollectionChanged;
+            this.source.PropertyChanged -= this.SourcePropertyChanged;
         }
 
         public IEnumerator<T> GetEnumerator()
@@ -122,7 +126,7 @@ namespace Perspex.Collections
                         ev = new NotifyCollectionChangedEventArgs(
                             NotifyCollectionChangedAction.Remove,
                             e.OldItems,
-                            e.NewStartingIndex);
+                            e.OldStartingIndex);
                         break;
                     case NotifyCollectionChangedAction.Replace:
                         ev = new NotifyCollectionChangedEventArgs(
@@ -139,6 +143,11 @@ namespace Perspex.Collections
                 this.CollectionChanged(this, ev);
             }
         }
+
+        private void SourcePropertyChanged(object sender, PropertyChangedEventArgs e)
+        {
+            this.PropertyChanged?.Invoke(this, e);
+        }
     }
 
     public class PerspexReadOnlyListView<TIn, TOut> : IPerspexReadOnlyList<TOut>, IDisposable
@@ -160,22 +169,17 @@ namespace Perspex.Collections
             if (source != null)
             {
                 this.source.CollectionChanged += this.SourceCollectionChanged;
+                this.source.PropertyChanged += this.SourcePropertyChanged;
             }
         }
 
-        public TOut this[int index]
+        public event NotifyCollectionChangedEventHandler CollectionChanged;
-        {
+
-            get
+        public event PropertyChangedEventHandler PropertyChanged;
-            {
-                return (this.convert != null) ?
-                    this.convert(this.source[index]) :
-                    (TOut)(object)this.source[index];
-            }
-        }
 
         public int Count
         {
-            get { return this.source.Count; }
+            get { return this.source?.Count ?? 0; }
         }
 
         public IPerspexReadOnlyList<TIn> Source
@@ -190,6 +194,7 @@ namespace Perspex.Collections
                 if (this.source != null)
                 {
                     this.source.CollectionChanged -= this.SourceCollectionChanged;
+                    this.source.PropertyChanged -= this.SourcePropertyChanged;
 
                     if (this.CollectionChanged != null)
                     {
@@ -206,6 +211,7 @@ namespace Perspex.Collections
                 if (this.source != null)
                 {
                     this.source.CollectionChanged += this.SourceCollectionChanged;
+                    this.source.PropertyChanged += this.SourcePropertyChanged;
 
                     if (this.CollectionChanged != null)
                     {
@@ -219,15 +225,22 @@ namespace Perspex.Collections
             }
         }
 
-        public event NotifyCollectionChangedEventHandler CollectionChanged;
+        public TOut this[int index]
-
+        {
-        public event PropertyChangedEventHandler PropertyChanged;
+            get
+            {
+                return (this.convert != null) ?
+                    this.convert(this.source[index]) :
+                    (TOut)(object)this.source[index];
+            }
+        }
 
         public void Dispose()
         {
             if (this.source != null)
             {
                 this.source.CollectionChanged -= this.SourceCollectionChanged;
+                this.source.PropertyChanged -= this.SourcePropertyChanged;
             }
         }
 
@@ -248,7 +261,7 @@ namespace Perspex.Collections
             return this.GetEnumerator();
         }
 
-        private IList<TOut> ConvertList(IEnumerable list)
+        private IList ConvertList(IEnumerable list)
         {
             return list.Cast<TIn>().Select(this.convert).ToList();
         }
@@ -271,7 +284,7 @@ namespace Perspex.Collections
                         ev = new NotifyCollectionChangedEventArgs(
                             NotifyCollectionChangedAction.Remove,
                             this.ConvertList(e.OldItems),
-                            e.NewStartingIndex);
+                            e.OldStartingIndex);
                         break;
                     case NotifyCollectionChangedAction.Replace:
                         ev = new NotifyCollectionChangedEventArgs(
@@ -288,6 +301,10 @@ namespace Perspex.Collections
                 this.CollectionChanged(this, ev);
             }
         }
-    }
 
+        private void SourcePropertyChanged(object sender, PropertyChangedEventArgs e)
+        {
+            this.PropertyChanged?.Invoke(this, e);
+        }
+    }
 }

Perspex.Base/Collections/PerspexSingleItemList.cs

@@ -1,5 +1,5 @@
 // -----------------------------------------------------------------------
-// <copyright file="PerspexList.cs" company="Steven Kirk">
+// <copyright file="PerspexSingleItemList.cs" company="Steven Kirk">
 // Copyright 2014 MIT Licence. See licence.md for more information.
 // </copyright>
 // -----------------------------------------------------------------------
@@ -36,18 +36,9 @@ namespace Perspex.Collections
             this.item = item;
         }
 
-        public T this[int index]
+        public event NotifyCollectionChangedEventHandler CollectionChanged;
-        {
-            get
-            {
-                if (index < 0 || index >= this.Count)
-                {
-                    throw new ArgumentOutOfRangeException();
-                }
 
-                return item;
+        public event PropertyChangedEventHandler PropertyChanged;
-            }
-        }
 
         public int Count
         {
@@ -96,9 +87,18 @@ namespace Perspex.Collections
             }
         }
 
-        public event NotifyCollectionChangedEventHandler CollectionChanged;
+        public T this[int index]
+        {
+            get
+            {
+                if (index < 0 || index >= this.Count)
+                {
+                    throw new ArgumentOutOfRangeException();
+                }
 
-        public event PropertyChangedEventHandler PropertyChanged;
+                return this.item;
+            }
+        }
 
         public IEnumerator<T> GetEnumerator()
         {

Perspex.Base/Diagnostics/PerspexObjectExtensions.cs

@@ -0,0 +1,35 @@
+// --------------------------------------------------------------------
+// <copyright file="PerspexObjectExtensions.cs" company="Steven Kirk">
+// Copyright 2014 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Diagnostics
+{
+    public static class PerspexObjectExtensions
+    {
+        public static PerspexPropertyValue GetDiagnostic(this PerspexObject o, PerspexProperty property)
+        {
+            var set = o.GetSetValues();
+
+            PriorityValue value;
+
+            if (set.TryGetValue(property, out value))
+            {
+                return new PerspexPropertyValue(
+                    property,
+                    value.Value,
+                    (BindingPriority)value.ValuePriority,
+                    value.GetDiagnostic());
+            }
+            else
+            {
+                return new PerspexPropertyValue(
+                    property, 
+                    o.GetValue(property),
+                    BindingPriority.Unset,
+                    "Unset");
+            }
+        }
+    }
+}

Perspex.Base/Diagnostics/PerspexPropertyValue.cs

@@ -1,4 +1,4 @@
-// -----------------------------------------------------------------------
+// --------------------------------------------------------------------
 // <copyright file="PerspexPropertyValue.cs" company="Steven Kirk">
 // Copyright 2014 MIT Licence. See licence.md for more information.
 // </copyright>
@@ -8,23 +8,24 @@ namespace Perspex.Diagnostics
 {
     public class PerspexPropertyValue
     {
-        public PerspexPropertyValue(PerspexProperty property, object value)
+        public PerspexPropertyValue(
+            PerspexProperty property, 
+            object value,
+            BindingPriority priority,
+            string diagnostic)
         {
             this.Property = property;
-            this.CurrentValue = value;
+            this.Value = value;
+            this.Priority = priority;
+            this.Diagnostic = diagnostic;
         }
 
-        public PerspexPropertyValue(PerspexProperty property, PriorityValue priorityValue)
+        public PerspexProperty Property { get; }
-        {
-            this.Property = property;
-            this.CurrentValue = priorityValue.Value;
-            this.PriorityValue = priorityValue;
-        }
 
-        public PerspexProperty Property { get; private set; }
+        public object Value { get; }
 
-        public object CurrentValue { get; private set; }
+        public BindingPriority Priority { get; }
 
-        public PriorityValue PriorityValue { get; private set; }
+        public string Diagnostic { get; }
     }
 }

Perspex.Base/GlobalSuppressions.cs

@@ -0,0 +1,14 @@
+// -----------------------------------------------------------------------
+// <copyright file="GlobalSuppressions.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+[assembly: System.Diagnostics.CodeAnalysis.SuppressMessage(
+    "StyleCop.CSharp.MaintainabilityRules",
+    "SA1401:Fields must be private",
+    Justification = "PerspexProperty fields should not be private.")]
+[assembly: System.Diagnostics.CodeAnalysis.SuppressMessage(
+    "StyleCop.CSharp.DocumentationRules",
+    "SA1609:Property documentation must have value",
+    Justification = "This rule is fscking pointless")]

Perspex.Base/IDescription.cs

@@ -6,8 +6,17 @@
 
 namespace Perspex
 {
+    /// <summary>
+    /// Interface for objects with a <see cref="Description"/>.
+    /// </summary>
     public interface IDescription
     {
+        /// <summary>
+        /// Gets the description of the object.
+        /// </summary>
+        /// <value>
+        /// The description of the object.
+        /// </value>
         string Description { get; }
     }
 }

Perspex.Base/Perspex.Base.csproj

@@ -15,6 +15,8 @@
     <ProjectTypeGuids>{786C830F-07A1-408B-BD7F-6EE04809D6DB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
     <TargetFrameworkProfile>Profile7</TargetFrameworkProfile>
     <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
+    <NuGetPackageImportStamp>
+    </NuGetPackageImportStamp>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DebugSymbols>true</DebugSymbols>
@@ -35,6 +37,11 @@
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="Binding.cs" />
+    <Compile Include="Diagnostics\PerspexObjectExtensions.cs" />
+    <Compile Include="GlobalSuppressions.cs" />
+    <Compile Include="PerspexObjectExtensions.cs" />
+    <Compile Include="PerspexProperty`1.cs" />
+    <Compile Include="PriorityBindingEntry.cs" />
     <Compile Include="Collections\IPerspexList.cs" />
     <Compile Include="Collections\PerspexReadOnlyListView.cs" />
     <Compile Include="Collections\PerspexList.cs" />
@@ -43,7 +50,6 @@
     <Compile Include="Diagnostics\PerspexPropertyValue.cs" />
     <Compile Include="IDescription.cs" />
     <Compile Include="Collections\PerspexListExtensions.cs" />
-    <Compile Include="IObservableDescription.cs" />
     <Compile Include="Collections\IPerspexReadOnlyList.cs" />
     <Compile Include="PerspexObject.cs" />
     <Compile Include="PerspexProperty.cs" />
@@ -51,17 +57,25 @@
     <Compile Include="Platform\IPlatformHandle.cs" />
     <Compile Include="Platform\IPlatformThreadingInterface.cs" />
     <Compile Include="Platform\PlatformHandle.cs" />
+    <Compile Include="PriorityLevel.cs" />
     <Compile Include="PriorityValue.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="Reactive\PerspexObservable.cs" />
     <Compile Include="Threading\Dispatcher.cs" />
     <Compile Include="Threading\DispatcherPriority.cs" />
     <Compile Include="Threading\DispatcherTimer.cs" />
     <Compile Include="Threading\MainLoop.cs" />
     <Compile Include="Threading\PerspexScheduler.cs" />
+    <Compile Include="Utilities\TypeUtilities.cs" />
   </ItemGroup>
   <ItemGroup>
-    <Reference Include="Splat">
+    <Reference Include="Serilog, Version=1.5.0.0, Culture=neutral, PublicKeyToken=24c2f752a8e58a10, processorArchitecture=MSIL">
-      <HintPath>..\packages\Splat.1.6.1\lib\Portable-net45+win+wpa81+wp80\Splat.dll</HintPath>
+      <HintPath>..\packages\Serilog.1.5.5\lib\portable-net45+win+wpa81+wp80+MonoAndroid10+MonoTouch10\Serilog.dll</HintPath>
+      <Private>True</Private>
+    </Reference>
+    <Reference Include="Splat, Version=1.6.2.0, Culture=neutral, processorArchitecture=MSIL">
+      <HintPath>..\packages\Splat.1.6.2\lib\Portable-net45+win+wpa81+wp80\Splat.dll</HintPath>
+      <Private>True</Private>
     </Reference>
     <Reference Include="System.Reactive.Core">
       <HintPath>..\packages\Rx-Core.2.2.5\lib\portable-windows8+net45+wp8\System.Reactive.Core.dll</HintPath>
@@ -86,14 +100,10 @@
       <Name>NGenerics</Name>
     </ProjectReference>
   </ItemGroup>
+  <ItemGroup>
+    <Analyzer Include="..\packages\StyleCop.Analyzers.1.0.0-alpha008\tools\analyzers\C#\StyleCop.Analyzers.dll" />
+  </ItemGroup>
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\Portable\$(TargetFrameworkVersion)\Microsoft.Portable.CSharp.targets" />
-  <Import Project="..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets" Condition="Exists('..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets')" />
-  <Target Name="EnsureNuGetPackageBuildImports" BeforeTargets="PrepareForBuild">
-    <PropertyGroup>
-      <ErrorText>This project references NuGet package(s) that are missing on this computer. Enable NuGet Package Restore to download them.  For more information, see http://go.microsoft.com/fwlink/?LinkID=322105. The missing file is {0}.</ErrorText>
-    </PropertyGroup>
-    <Error Condition="!Exists('..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets')" Text="$([System.String]::Format('$(ErrorText)', '..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets'))" />
-  </Target>
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.
   <Target Name="BeforeBuild">

Perspex.Base/PerspexObject.cs

@@ -10,10 +10,13 @@ namespace Perspex
     using System.Collections.Generic;
     using System.ComponentModel;
     using System.Linq;
+    using System.Reactive.Disposables;
     using System.Reactive.Linq;
     using System.Reflection;
-    using Perspex.Diagnostics;
+    using Perspex.Reactive;
-    using Splat;
+    using Serilog;
+    using Serilog.Core.Enrichers;
+    using Perspex.Utilities;
 
     /// <summary>
     /// The priority of a binding.
@@ -23,20 +26,20 @@ namespace Perspex
         /// <summary>
         /// A value that comes from an animation.
         /// </summary>
-        Animation = -1,
+        Animation = -2,
 
         /// <summary>
         /// A local value.
         /// </summary>
-        LocalValue,
+        LocalValue = 0,
 
         /// <summary>
         /// A triggered style binding.
         /// </summary>
         /// <remarks>
-        /// A style trigger is a selector such as .class which overrides a 
+        /// A style trigger is a selector such as .class which overrides a
         /// <see cref="TemplatedParent"/> binding. In this way, a basic control can have
-        /// for example a Background from the templated parent which changes when the 
+        /// for example a Background from the templated parent which changes when the
         /// control has the :pointerover class.
         /// </remarks>
         StyleTrigger,
@@ -63,7 +66,7 @@ namespace Perspex
     /// <remarks>
     /// This class is analogous to DependencyObject in WPF.
     /// </remarks>
-    public class PerspexObject : INotifyPropertyChanged, IEnableLogger
+    public class PerspexObject : INotifyPropertyChanged
     {
         /// <summary>
         /// The registered properties by type.
@@ -87,25 +90,33 @@ namespace Perspex
         /// </summary>
         private PropertyChangedEventHandler inpcChanged;
 
+        /// <summary>
+        /// A serilog logger for logging property events.
+        /// </summary>
+        private ILogger propertyLog;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="PerspexObject"/> class.
         /// </summary>
         public PerspexObject()
         {
-            foreach (var p in this.GetAllValues())
+            this.propertyLog = Log.ForContext(new[]
             {
-                var priority = p.PriorityValue != null ? 
+                new PropertyEnricher("Area", "Property"),
-                    (BindingPriority)p.PriorityValue.ValuePriority : 
+                new PropertyEnricher("SourceContext", this.GetType()),
-                    BindingPriority.LocalValue;
+                new PropertyEnricher("Id", this.GetHashCode()),
+            });
 
+            foreach (var property in this.GetRegisteredProperties())
+            {
                 var e = new PerspexPropertyChangedEventArgs(
-                    this, 
+                    this,
-                    p.Property, 
+                    property,
-                    PerspexProperty.UnsetValue, 
+                    PerspexProperty.UnsetValue,
-                    p.CurrentValue,
+                    property.GetDefaultValue(this.GetType()),
-                    priority);
+                    BindingPriority.Unset);
 
-                p.Property.NotifyInitialized(e);
+                property.NotifyInitialized(e);
             }
         }
 
@@ -124,9 +135,12 @@ namespace Perspex
         }
 
         /// <summary>
-        /// Gets or sets the parent object that inherited <see cref="PerspexProperty"/> values 
+        /// Gets or sets the parent object that inherited <see cref="PerspexProperty"/> values
         /// are inherited from.
         /// </summary>
+        /// <value>
+        /// The inheritance parent.
+        /// </value>
         protected PerspexObject InheritanceParent
         {
             get
@@ -200,8 +214,8 @@ namespace Perspex
 
             set
             {
-                BindingMode mode = (binding.Mode == BindingMode.Default) ? 
+                BindingMode mode = (binding.Mode == BindingMode.Default) ?
-                    binding.Property.DefaultBindingMode : 
+                    binding.Property.DefaultBindingMode :
                     binding.Mode;
                 Binding sourceBinding = value as Binding;
 
@@ -217,7 +231,7 @@ namespace Perspex
                         this.Bind(binding.Property, value, binding.Priority);
                         break;
                     case BindingMode.OneTime:
-                        this.SetValue(binding.Property, sourceBinding.Source.GetValue(sourceBinding.Property));
+                        this.SetValue(binding.Property, sourceBinding.Source.GetValue(sourceBinding.Property), binding.Priority);
                         break;
                     case BindingMode.OneWayToSource:
                         sourceBinding.Source.Bind(sourceBinding.Property, this.GetObservable(binding.Property), binding.Priority);
@@ -262,7 +276,7 @@ namespace Perspex
         /// <param name="type">The type.</param>
         /// <param name="property">The property.</param>
         /// <remarks>
-        /// You won't usually want to call this method directly, instead use the 
+        /// You won't usually want to call this method directly, instead use the
         /// <see cref="PerspexProperty.Register"/> method.
         /// </remarks>
         public static void Register(Type type, PerspexProperty property)
@@ -291,7 +305,7 @@ namespace Perspex
         public void ClearValue(PerspexProperty property)
         {
             Contract.Requires<NullReferenceException>(property != null);
-            
+
             this.SetValue(property, PerspexProperty.UnsetValue);
         }
 
@@ -304,31 +318,35 @@ namespace Perspex
         {
             Contract.Requires<NullReferenceException>(property != null);
 
-            return Observable.Create<object>(observer =>
+            return new PerspexObservable<object>(
-            {
+                observer =>
-                EventHandler<PerspexPropertyChangedEventArgs> handler = (s, e) =>
                 {
-                    if (e.Property == property)
+                    EventHandler<PerspexPropertyChangedEventArgs> handler = (s, e) =>
                     {
-                        observer.OnNext(e.NewValue);
+                        if (e.Property == property)
-                    }
+                        {
-                };
+                            observer.OnNext(e.NewValue);
+                        }
+                    };
 
-                this.PropertyChanged += handler;
+                    observer.OnNext(this.GetValue(property));
 
-                return () =>
+                    this.PropertyChanged += handler;
-                {
+
-                    this.PropertyChanged -= handler;
+                    return Disposable.Create(() =>
-                };
+                    {
-            }).StartWith(this.GetValue(property));
+                        this.PropertyChanged -= handler;
+                    });
+                },
+                this.GetObservableDescription(property));
         }
 
         /// <summary>
         /// Gets an observable for a <see cref="PerspexProperty"/>.
         /// </summary>
-        /// <typeparam name="T"></typeparam>
+        /// <typeparam name="T">The property type.</typeparam>
-        /// <param name="property"></param>
+        /// <param name="property">The property.</param>
-        /// <returns></returns>
+        /// <returns>An observable.</returns>
         public IObservable<T> GetObservable<T>(PerspexProperty<T> property)
         {
             Contract.Requires<NullReferenceException>(property != null);
@@ -339,28 +357,31 @@ namespace Perspex
         /// <summary>
         /// Gets an observable for a <see cref="PerspexProperty"/>.
         /// </summary>
-        /// <typeparam name="T"></typeparam>
+        /// <typeparam name="T">The type of the property.</typeparam>
-        /// <param name="property"></param>
+        /// <param name="property">The property.</param>
-        /// <returns></returns>
+        /// <returns>An observable which when subscribed pushes the old and new values of the
+        /// property each time it is changed.</returns>
         public IObservable<Tuple<T, T>> GetObservableWithHistory<T>(PerspexProperty<T> property)
         {
-            return Observable.Create<Tuple<T, T>>(observer =>
+            return new PerspexObservable<Tuple<T, T>>(
-            {
+                observer =>
-                EventHandler<PerspexPropertyChangedEventArgs> handler = (s, e) =>
                 {
-                    if (e.Property == property)
+                    EventHandler<PerspexPropertyChangedEventArgs> handler = (s, e) =>
                     {
-                        observer.OnNext(Tuple.Create((T)e.OldValue, (T)e.NewValue));
+                        if (e.Property == property)
-                    }
+                        {
-                };
+                            observer.OnNext(Tuple.Create((T)e.OldValue, (T)e.NewValue));
+                        }
+                    };
 
-                this.PropertyChanged += handler;
+                    this.PropertyChanged += handler;
 
-                return () =>
+                    return Disposable.Create(() =>
-                {
+                    {
-                    this.PropertyChanged -= handler;
+                        this.PropertyChanged -= handler;
-                };
+                    });
-            });
+                },
+                this.GetObservableDescription(property));
         }
 
         /// <summary>
@@ -396,6 +417,7 @@ namespace Perspex
         /// <summary>
         /// Gets a <see cref="PerspexProperty"/> value.
         /// </summary>
+        /// <typeparam name="T">The type of the property.</typeparam>
         /// <param name="property">The property.</param>
         /// <returns>The value.</returns>
         public T GetValue<T>(PerspexProperty<T> property)
@@ -405,23 +427,12 @@ namespace Perspex
             return (T)this.GetValue((PerspexProperty)property);
         }
 
-        public IEnumerable<PerspexPropertyValue> GetAllValues()
+        /// <summary>
-        {
+        /// Gets all properties that are registered on this object.
-            foreach (PerspexProperty property in this.GetRegisteredProperties())
+        /// </summary>
-            {
+        /// <returns>
-                PriorityValue value;
+        /// A collection of <see cref="PerspexProperty"/> objects.
-
+        /// </returns>
-                if (this.values.TryGetValue(property, out value))
-                {
-                    yield return new PerspexPropertyValue(property, value);
-                }
-                else
-                {
-                    yield return new PerspexPropertyValue(property, this.GetValue(property));
-                }
-            }
-        }
-
         public IEnumerable<PerspexProperty> GetRegisteredProperties()
         {
             Type type = this.GetType();
@@ -442,17 +453,6 @@ namespace Perspex
             }
         }
 
-        /// <summary>
-        /// Gets all of the <see cref="PerspexProperty"/> values explicitly set on this object.
-        /// </summary>
-        public IEnumerable<PerspexPropertyValue> GetSetValues()
-        {
-            foreach (var value in this.values)
-            {
-                yield return new PerspexPropertyValue(value.Key, value.Value);
-            }
-        }
-
         /// <summary>
         /// Checks whether a <see cref="PerspexProperty"/> is set on this object.
         /// </summary>
@@ -497,11 +497,14 @@ namespace Perspex
         /// </summary>
         /// <param name="property">The property.</param>
         /// <param name="value">The value.</param>
-        public void SetValue(PerspexProperty property, object value)
+        /// <param name="priority">The priority of the value.</param>
+        public void SetValue(
+            PerspexProperty property,
+            object value,
+            BindingPriority priority = BindingPriority.LocalValue)
         {
             Contract.Requires<NullReferenceException>(property != null);
 
-            const int Priority = (int)BindingPriority.LocalValue;
             PriorityValue v;
 
             if (!this.IsRegistered(property))
@@ -512,13 +515,13 @@ namespace Perspex
                     this.GetType()));
             }
 
-            if (!PriorityValue.IsValidValue(value, property.PropertyType))
+            if (!TypeUtilities.TryCast(property.PropertyType, value, out value))
             {
                 throw new InvalidOperationException(string.Format(
                     "Invalid value for Property '{0}': {1} ({2})",
                     property.Name,
                     value,
-                    value.GetType().FullName));
+                    value?.GetType().FullName ?? "(null)"));
             }
 
             if (!this.values.TryGetValue(property, out v))
@@ -531,15 +534,13 @@ namespace Perspex
                 v = this.CreatePriorityValue(property);
                 this.values.Add(property, v);
             }
-            
+
-            this.Log().Debug(
+            this.propertyLog.Verbose(
-                "Set local value of {0}.{1} (#{2:x8}) to {3}",
+                "Set {Property} to {$Value} with priority {Priority}",
-                this.GetType().Name,
+                property,
-                property.Name,
+                value,
-                this.GetHashCode(),
+                priority);
-                value);
+            v.SetDirectValue(value, (int)priority);
-
-            v.Replace(Observable.Never<object>().StartWith(value), Priority);
         }
 
         /// <summary>
@@ -548,17 +549,20 @@ namespace Perspex
         /// <typeparam name="T">The type of the property.</typeparam>
         /// <param name="property">The property.</param>
         /// <param name="value">The value.</param>
-        public void SetValue<T>(PerspexProperty<T> property, T value)
+        /// <param name="priority">The priority of the value.</param>
+        public void SetValue<T>(
+            PerspexProperty<T> property,
+            T value,
+            BindingPriority priority = BindingPriority.LocalValue)
         {
             Contract.Requires<NullReferenceException>(property != null);
 
-            this.SetValue((PerspexProperty)property, value);
+            this.SetValue((PerspexProperty)property, value, priority);
         }
 
         /// <summary>
         /// Binds a <see cref="PerspexProperty"/> to an observable.
         /// </summary>
-        /// <typeparam name="T">The type of the property.</typeparam>
         /// <param name="property">The property.</param>
         /// <param name="source">The observable.</param>
         /// <param name="priority">The priority of the binding.</param>
@@ -575,27 +579,27 @@ namespace Perspex
             PriorityValue v;
             IDescription description = source as IDescription;
 
+            if (!this.IsRegistered(property))
+            {
+                throw new InvalidOperationException(string.Format(
+                    "Property '{0}' not registered on '{1}'",
+                    property.Name,
+                    this.GetType()));
+            }
+
             if (!this.values.TryGetValue(property, out v))
             {
                 v = this.CreatePriorityValue(property);
                 this.values.Add(property, v);
             }
 
-            this.Log().Debug(
+            this.propertyLog.Verbose(
-                "Bound value of {0}.{1} (#{2:x8}) to {3}",
+                "Bound {Property} to {Binding} with priority {Priority}",
-                this.GetType().Name,
+                property,
-                property.Name,
+                source,
-                this.GetHashCode(),
+                priority);
-                description != null ? description.Description : "[Anonymous]");
 
-            if (priority == BindingPriority.LocalValue)
+            return v.Add(source, (int)priority);
-            {
-                return v.Replace(source, (int)priority);
-            }
-            else
-            {
-                return v.Add(source, (int)priority);
-            }
         }
 
         /// <summary>
@@ -609,8 +613,8 @@ namespace Perspex
         /// A disposable which can be used to terminate the binding.
         /// </returns>
         public IDisposable Bind<T>(
-            PerspexProperty<T> property, 
+            PerspexProperty<T> property,
-            IObservable<T> source, 
+            IObservable<T> source,
             BindingPriority priority = BindingPriority.LocalValue)
         {
             Contract.Requires<NullReferenceException>(property != null);
@@ -624,20 +628,22 @@ namespace Perspex
         /// <param name="property">The property on this object.</param>
         /// <param name="source">The source object.</param>
         /// <param name="sourceProperty">The property on the source object.</param>
+        /// <param name="priority">The priority of the binding.</param>
         /// <returns>
         /// A disposable which can be used to terminate the binding.
         /// </returns>
         /// <remarks>
-        /// The binding is first carried out from <paramref name="source"/> to this. Two-way 
+        /// The binding is first carried out from <paramref name="source"/> to this.
-        /// bindings are always at the LocalValue priority.
         /// </remarks>
-        public void BindTwoWay(
+        public IDisposable BindTwoWay(
-            PerspexProperty property, 
+            PerspexProperty property,
-            PerspexObject source, 
+            PerspexObject source,
-            PerspexProperty sourceProperty)
+            PerspexProperty sourceProperty,
+            BindingPriority priority = BindingPriority.LocalValue)
         {
-            source.GetObservable(sourceProperty).Subscribe(x => this.SetValue(property, x));
+            return new CompositeDisposable(
-            this.GetObservable(property).Subscribe(x => source.SetValue(sourceProperty, x));
+                this.Bind(property, source.GetObservable(sourceProperty)),
+                source.Bind(sourceProperty, this.GetObservable(property)));
         }
 
         /// <summary>
@@ -654,6 +660,15 @@ namespace Perspex
             }
         }
 
+        /// <summary>
+        /// Gets all priority values set on the object.
+        /// </summary>
+        /// <returns>A collection of property/value tuples.</returns>
+        internal IDictionary<PerspexProperty, PriorityValue> GetSetValues()
+        {
+            return this.values;
+        }
+
         /// <summary>
         /// Forces re-coercion of properties when a property value changes.
         /// </summary>
@@ -707,13 +722,12 @@ namespace Perspex
                 {
                     this.RaisePropertyChanged(property, oldValue, newValue, (BindingPriority)result.ValuePriority);
 
-                    this.Log().Debug(
+                    this.propertyLog.Verbose(
-                        "Value of {0}.{1} (#{2:x8}) changed from {3} to {4}",
+                        "{Property} changed from {$Old} to {$Value} with priority {Priority}",
-                        this.GetType().Name,
+                        property,
-                        property.Name,
-                        this.GetHashCode(),
                         oldValue,
-                        newValue);
+                        newValue,
+                        (BindingPriority)result.ValuePriority);
                 }
             });
 
@@ -755,6 +769,16 @@ namespace Perspex
             }
         }
 
+        /// <summary>
+        /// Gets a description of a property that van be used in observables.
+        /// </summary>
+        /// <param name="property">The property</param>
+        /// <returns>The description.</returns>
+        private string GetObservableDescription(PerspexProperty property)
+        {
+            return string.Format("{0}.{1}", this.GetType().Name, property.Name);
+        }
+
         /// <summary>
         /// Raises the <see cref="PropertyChanged"/> event.
         /// </summary>
@@ -763,17 +787,17 @@ namespace Perspex
         /// <param name="newValue">The new property value.</param>
         /// <param name="priority">The priority of the binding that produced the value.</param>
         private void RaisePropertyChanged(
-            PerspexProperty property, 
+            PerspexProperty property,
-            object oldValue, 
+            object oldValue,
-            object newValue, 
+            object newValue,
             BindingPriority priority)
         {
             Contract.Requires<NullReferenceException>(property != null);
 
             PerspexPropertyChangedEventArgs e = new PerspexPropertyChangedEventArgs(
-                this, 
+                this,
-                property, 
+                property,
-                oldValue, 
+                oldValue,
                 newValue,
                 priority);
 

Perspex.Base/PerspexObjectExtensions.cs

@@ -0,0 +1,53 @@
+// -----------------------------------------------------------------------
+// <copyright file="PerspexObjectExtensions.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex
+{
+    using System;
+    using System.Reactive.Linq;
+
+    /// <summary>
+    /// Provides extension methods for <see cref="PerspexObject"/> and related classes.
+    /// </summary>
+    public static class PerspexObjectExtensions
+    {
+        /// <summary>
+        /// Subscribes to a property changed notifications for changes that originate from a
+        /// <typeparamref name="TTarget"/>.
+        /// </summary>
+        /// <typeparam name="TTarget">The type of the property change sender.</typeparam>
+        /// <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>
+        public static IDisposable AddClassHandler<TTarget>(
+            this IObservable<PerspexPropertyChangedEventArgs> observable,
+            Func<TTarget, Action<PerspexPropertyChangedEventArgs>> handler)
+            where TTarget : class
+        {
+            return observable.Subscribe(e => SubscribeAdapter(e, handler));
+        }
+
+        /// <summary>
+        /// Observer method for <see cref="AddClassHandler{TTarget}(IObservable{PerspexPropertyChangedEventArgs},
+        /// Func{TTarget, Action{PerspexPropertyChangedEventArgs}})"/>.
+        /// </summary>
+        /// <typeparam name="TTarget">The sender type to accept.</typeparam>
+        /// <param name="e">The event args.</param>
+        /// <param name="handler">Given a TTarget, returns the handler.</param>
+        private static void SubscribeAdapter<TTarget>(
+            PerspexPropertyChangedEventArgs e,
+            Func<TTarget, Action<PerspexPropertyChangedEventArgs>> handler)
+            where TTarget : class
+        {
+            var target = e.Sender as TTarget;
+
+            if (target != null)
+            {
+                handler(target)(e);
+            }
+        }
+    }
+}

Perspex.Base/PerspexProperty.cs

@@ -10,6 +10,7 @@ namespace Perspex
     using System.Collections.Generic;
     using System.Reactive.Subjects;
     using System.Reflection;
+    using Perspex.Utilities;
 
     /// <summary>
     /// A perspex property.
@@ -22,6 +23,7 @@ namespace Perspex
         /// <summary>
         /// Represents an unset property value.
         /// </summary>
+        [System.Diagnostics.CodeAnalysis.SuppressMessage("StyleCop.CSharp.MaintainabilityRules", "SA1401:Fields must be private", Justification = "It's readonly")]
         public static readonly object UnsetValue = new Unset();
 
         /// <summary>
@@ -39,11 +41,6 @@ namespace Perspex
         /// </summary>
         private Subject<PerspexPropertyChangedEventArgs> changed = new Subject<PerspexPropertyChangedEventArgs>();
 
-        /// <summary>
-        /// The coerce function.
-        /// </summary>
-        private Func<PerspexObject, object, object> coerce;
-
         /// <summary>
         /// Initializes a new instance of the <see cref="PerspexProperty"/> class.
         /// </summary>
@@ -54,14 +51,16 @@ namespace Perspex
         /// <param name="inherits">Whether the property inherits its value.</param>
         /// <param name="defaultBindingMode">The default binding mode for the property.</param>
         /// <param name="coerce">A coercion function.</param>
+        /// <param name="isAttached">Whether the property is an attached property.</param>
         public PerspexProperty(
             string name,
             Type valueType,
             Type ownerType,
             object defaultValue,
-            bool inherits,
+            bool inherits = false,
-            BindingMode defaultBindingMode,
+            BindingMode defaultBindingMode = BindingMode.Default,
-            Func<PerspexObject, object, object> coerce)
+            Func<PerspexObject, object, object> coerce = null,
+            bool isAttached = false)
         {
             Contract.Requires<NullReferenceException>(name != null);
             Contract.Requires<NullReferenceException>(valueType != null);
@@ -74,38 +73,64 @@ namespace Perspex
             this.Inherits = inherits;
             this.DefaultBindingMode = defaultBindingMode;
             this.Coerce = coerce;
+            this.IsAttached = isAttached;
         }
 
         /// <summary>
         /// Gets the name of the property.
         /// </summary>
-        public string Name { get; private set; }
+        /// <value>
+        /// The name of the property.
+        /// </value>
+        public string Name { get; }
 
         /// <summary>
         /// Gets the type of the property's value.
         /// </summary>
-        public Type PropertyType { get; private set; }
+        /// <value>
+        /// The type of the property's value.
+        /// </value>
+        public Type PropertyType { get; }
 
         /// <summary>
         /// Gets the type of the class that registers the property.
         /// </summary>
-        public Type OwnerType { get; private set; }
+        /// <value>
+        /// The type of the class that registers the property.
+        /// </value>
+        public Type OwnerType { get; }
 
         /// <summary>
         /// Gets a value indicating whether the property inherits its value.
         /// </summary>
-        public bool Inherits { get; private set; }
+        /// <value>
+        /// A value indicating whether the property inherits its value.
+        /// </value>
+        public bool Inherits { get; }
 
         /// <summary>
         /// Gets the default binding mode for the property.
         /// </summary>
-        /// <returns></returns>
+        /// <value>
-        public BindingMode DefaultBindingMode { get; private set; }
+        /// The default binding mode for the property.
+        /// </value>
+        public BindingMode DefaultBindingMode { get; }
 
         /// <summary>
         /// Gets the property's coerce function.
         /// </summary>
-        public Func<PerspexObject, object, object> Coerce { get; private set; }
+        /// <value>
+        /// The property's coerce function.
+        /// </value>
+        public Func<PerspexObject, object, object> Coerce { get; }
+
+        /// <summary>
+        /// Gets a value indicating whether this is an attached property.
+        /// </summary>
+        /// <value>
+        /// A value indicating whether this is an attached property.
+        /// </value>
+        public bool IsAttached { get; }
 
         /// <summary>
         /// Gets an observable that is fired when this property is initialized on a
@@ -113,24 +138,62 @@ namespace Perspex
         /// </summary>
         /// <remarks>
         /// This observable is fired each time a new <see cref="PerspexObject"/> is constructed
-        /// for all properties registered on the object's type. The default value of the property 
+        /// for all properties registered on the object's type. The default value of the property
-        /// for the object is passed in the args' NewValue (OldValue will always be 
+        /// for the object is passed in the args' NewValue (OldValue will always be
         /// <see cref="UnsetValue"/>.
         /// </remarks>
+        /// <value>
+        /// An observable that is fired when this property is initialized on a new
+        /// <see cref="PerspexObject"/> instance.
+        /// </value>
         public IObservable<PerspexPropertyChangedEventArgs> Initialized
         {
             get { return this.initialized; }
         }
 
         /// <summary>
-        /// Gets an observable that is fired when this property changes on any 
+        /// Gets an observable that is fired when this property changes on any
         /// <see cref="PerspexObject"/> instance.
         /// </summary>
+        /// <value>
+        /// An observable that is fired when this property changes on any
+        /// <see cref="PerspexObject"/> instance.
+        /// </value>
         public IObservable<PerspexPropertyChangedEventArgs> Changed
         {
             get { return this.changed; }
         }
 
+        /// <summary>
+        /// Provides access to a property's binding via the <see cref="PerspexObject"/>
+        /// indexer.
+        /// </summary>
+        /// <param name="property">The property.</param>
+        /// <returns>A <see cref="Binding"/> describing the binding.</returns>
+        public static Binding operator !(PerspexProperty property)
+        {
+            return new Binding
+            {
+                Priority = BindingPriority.LocalValue,
+                Property = property,
+            };
+        }
+
+        /// <summary>
+        /// Provides access to a property's template binding via the <see cref="PerspexObject"/>
+        /// indexer.
+        /// </summary>
+        /// <param name="property">The property.</param>
+        /// <returns>A <see cref="Binding"/> describing the binding.</returns>
+        public static Binding operator ~(PerspexProperty property)
+        {
+            return new Binding
+            {
+                Priority = BindingPriority.TemplatedParent,
+                Property = property,
+            };
+        }
+
         /// <summary>
         /// Registers a <see cref="PerspexProperty"/>.
         /// </summary>
@@ -158,7 +221,8 @@ namespace Perspex
                 defaultValue,
                 inherits,
                 defaultBindingMode,
-                coerce);
+                coerce,
+                false);
 
             PerspexObject.Register(typeof(TOwner), result);
 
@@ -183,17 +247,17 @@ namespace Perspex
             bool inherits = false,
             BindingMode defaultBindingMode = BindingMode.OneWay,
             Func<PerspexObject, TValue, TValue> coerce = null)
-            where TOwner : PerspexObject
         {
             Contract.Requires<NullReferenceException>(name != null);
 
             PerspexProperty<TValue> result = new PerspexProperty<TValue>(
-                typeof(TOwner) + "." + name,
+                name,
                 typeof(TOwner),
                 defaultValue,
                 inherits,
                 defaultBindingMode,
-                coerce);
+                coerce,
+                true);
 
             PerspexObject.Register(typeof(THost), result);
 
@@ -201,37 +265,43 @@ namespace Perspex
         }
 
         /// <summary>
-        /// Provides access to a property's binding via the <see cref="PerspexObject"/> 
+        /// Registers an attached <see cref="PerspexProperty"/>.
-        /// indexer.
         /// </summary>
-        /// <param name="property">The property.</param>
+        /// <typeparam name="THost">The type of the class that the property is to be registered on.</typeparam>
-        /// <returns>A <see cref="Binding"/> describing the binding.</returns>
+        /// <typeparam name="TValue">The type of the property's value.</typeparam>
-        public static Binding operator !(PerspexProperty property)
+        /// <param name="name">The name of the property.</param>
+        /// <param name="ownerType">The type of the class that is registering the property.</param>
+        /// <param name="defaultValue">The default value of the property.</param>
+        /// <param name="inherits">Whether the property inherits its value.</param>
+        /// <param name="defaultBindingMode">The default binding mode for the property.</param>
+        /// <param name="coerce">A coercion function.</param>
+        /// <returns>A <see cref="PerspexProperty{TValue}"/></returns>
+        public static PerspexProperty<TValue> RegisterAttached<THost, TValue>(
+            string name,
+            Type ownerType,
+            TValue defaultValue = default(TValue),
+            bool inherits = false,
+            BindingMode defaultBindingMode = BindingMode.OneWay,
+            Func<PerspexObject, TValue, TValue> coerce = null)
         {
-            return new Binding
+            Contract.Requires<NullReferenceException>(name != null);
-            {
-                Priority = BindingPriority.LocalValue,
-                Property = property,
-            };
-        }
 
-        /// <summary>
+            PerspexProperty<TValue> result = new PerspexProperty<TValue>(
-        /// Provides access to a property's template binding via the <see cref="PerspexObject"/>
+                name,
-        /// indexer.
+                ownerType,
-        /// </summary>
+                defaultValue,
-        /// <param name="property">The property.</param>
+                inherits,
-        /// <returns>A <see cref="Binding"/> describing the binding.</returns>
+                defaultBindingMode,
-        public static Binding operator ~(PerspexProperty property)
+                coerce,
-        {
+                true);
-            return new Binding
+
-            {
+            PerspexObject.Register(typeof(THost), result);
-                Priority = BindingPriority.TemplatedParent,
+
-                Property = property,
+            return result;
-            };
         }
 
         /// <summary>
-        /// Returns a binding accessor that can be passed to <see cref="PerspexObject"/>'s [] 
+        /// Returns a binding accessor that can be passed to <see cref="PerspexObject"/>'s []
         /// operator to initiate a binding.
         /// </summary>
         /// <returns>A <see cref="Binding"/>.</returns>
@@ -270,23 +340,28 @@ namespace Perspex
             return this.defaultValues[this.OwnerType];
         }
 
+        /// <summary>
+        /// Checks whether the <paramref name="value"/> is valid for the property.
+        /// </summary>
+        /// <param name="value">The value.</param>
+        /// <returns>True if the value is valid, otherwise false.</returns>
         public bool IsValidValue(object value)
         {
-            if (value == UnsetValue)
+            return TypeUtilities.TryCast(this.PropertyType, value, out value);
-            {
+        }
-                return true;
-            }
-            else if (value == null)
-            {
-                return !this.PropertyType.GetTypeInfo().IsValueType ||
-                    Nullable.GetUnderlyingType(this.PropertyType) != null;
-            }
 
-            return this.PropertyType.GetTypeInfo().IsAssignableFrom(value.GetType().GetTypeInfo());
+        /// <summary>
+        /// Overrides the default value for the property on the specified type.
+        /// </summary>
+        /// <typeparam name="T">The type.</typeparam>
+        /// <param name="defaultValue">The default value.</param>
+        public void OverrideDefaultValue<T>(object defaultValue)
+        {
+            this.OverrideDefaultValue(typeof(T), defaultValue);
         }
 
         /// <summary>
-        /// Gets the default value for the property on the specified type.
+        /// Overrides the default value for the property on the specified type.
         /// </summary>
         /// <param name="type">The type.</param>
         /// <param name="defaultValue">The default value.</param>
@@ -294,7 +369,15 @@ namespace Perspex
         {
             Contract.Requires<NullReferenceException>(type != null);
 
-            // TODO: Ensure correct type.
+            if (!TypeUtilities.TryCast(this.PropertyType, defaultValue, out defaultValue))
+            {
+                throw new InvalidOperationException(string.Format(
+                    "Invalid value for Property '{0}': {1} ({2})",
+                    this.Name,
+                    defaultValue,
+                    defaultValue.GetType().FullName));
+            }
+
             if (this.defaultValues.ContainsKey(type))
             {
                 throw new InvalidOperationException("Default value is already set for this property.");
@@ -303,93 +386,46 @@ namespace Perspex
             this.defaultValues.Add(type, defaultValue);
         }
 
+        /// <summary>
+        /// Gets the string representation of the property.
+        /// </summary>
+        /// <returns>The property's string representation.</returns>
         public override string ToString()
         {
             return this.Name;
         }
 
+        /// <summary>
+        /// Notifies the <see cref="Initialized"/> observable.
+        /// </summary>
+        /// <param name="e">The observable arguments.</param>
         internal void NotifyInitialized(PerspexPropertyChangedEventArgs e)
         {
             this.initialized.OnNext(e);
         }
 
+        /// <summary>
+        /// Notifies the <see cref="Changed"/> observable.
+        /// </summary>
+        /// <param name="e">The observable arguments.</param>
         internal void NotifyChanged(PerspexPropertyChangedEventArgs e)
         {
             this.changed.OnNext(e);
         }
 
+        /// <summary>
+        /// Class representing the <see cref="UnsetValue"/>.
+        /// </summary>
         private class Unset
         {
+            /// <summary>
+            /// Returns the string representation of the <see cref="UnsetValue"/>.
+            /// </summary>
+            /// <returns>The string "(unset)".</returns>
             public override string ToString()
             {
-                return "{Unset}";
+                return "(unset)";
             }
         }
     }
-
-    /// <summary>
-    /// A typed perspex property.
-    /// </summary>
-    public class PerspexProperty<TValue> : PerspexProperty
-    {
-        /// <summary>
-        /// Initializes a new instance of the <see cref="PerspexProperty"/> class.
-        /// </summary>
-        /// <param name="name">The name of the property.</param>
-        /// <param name="ownerType">The type of the class that registers the property.</param>
-        /// <param name="defaultValue">The default value of the property.</param>
-        /// <param name="inherits">Whether the property inherits its value.</param>
-        /// <param name="defaultBindingMode">The default binding mode for the property.</param>
-        /// <param name="coerce">A coercion function.</param>
-        public PerspexProperty(
-            string name,
-            Type ownerType,
-            TValue defaultValue,
-            bool inherits,
-            BindingMode defaultBindingMode,
-            Func<PerspexObject, TValue, TValue> coerce)
-            : base(
-                name, 
-                typeof(TValue), 
-                ownerType, 
-                defaultValue, 
-                inherits, 
-                defaultBindingMode,
-                Convert(coerce))
-        {
-            Contract.Requires<NullReferenceException>(name != null);
-            Contract.Requires<NullReferenceException>(ownerType != null);
-        }
-
-        /// <summary>
-        /// Registers the property on another type.
-        /// </summary>
-        /// <typeparam name="TOwner">The type of the additional owner.</typeparam>
-        /// <returns>The property.</returns>
-        public PerspexProperty<TValue> AddOwner<TOwner>()
-        {
-            PerspexObject.Register(typeof(TOwner), this);
-            return this;
-        }
-
-        /// <summary>
-        /// Gets the default value for the property on the specified type.
-        /// </summary>
-        /// <typeparam name="T">The type.</typeparam>
-        /// <returns>The default value.</returns>
-        public TValue GetDefaultValue<T>()
-        {
-            return (TValue)this.GetDefaultValue(typeof(T));
-        }
-
-        /// <summary>
-        /// Converts from a typed coercion function to an untyped.
-        /// </summary>
-        /// <param name="f">The typed coercion function.</param>
-        /// <returns>Te untyped coercion function.</returns>
-        private static Func<PerspexObject, object, object> Convert(Func<PerspexObject, TValue, TValue> f)
-        {
-            return f != null ? (o, v) => f(o, (TValue)v) : (Func<PerspexObject, object, object>)null;
-        }
-    }
 }

Perspex.Base/PerspexPropertyChangedEventArgs.cs

@@ -11,6 +11,14 @@ namespace Perspex
     /// </summary>
     public class PerspexPropertyChangedEventArgs
     {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PerspexPropertyChangedEventArgs"/> class.
+        /// </summary>
+        /// <param name="sender">The object that the property changed on.</param>
+        /// <param name="property">The property that changed.</param>
+        /// <param name="oldValue">The old value of the property.</param>
+        /// <param name="newValue">The new value of the property.</param>
+        /// <param name="priority">The priority of the binding that produced the value.</param>
         public PerspexPropertyChangedEventArgs(
             PerspexObject sender,
             PerspexProperty property,
@@ -28,27 +36,39 @@ namespace Perspex
         /// <summary>
         /// Gets the <see cref="PerspexObject"/> that the property changed on.
         /// </summary>
-        /// <returns></returns>
+        /// <value>The sender object.</value>
         public PerspexObject Sender { get; private set; }
 
         /// <summary>
         /// Gets the property that changed.
         /// </summary>
+        /// <value>
+        /// The property that changed.
+        /// </value>
         public PerspexProperty Property { get; private set; }
 
         /// <summary>
         /// Gets the old value of the property.
         /// </summary>
+        /// <value>
+        /// The old value of the property.
+        /// </value>
         public object OldValue { get; private set; }
 
         /// <summary>
         /// Gets the new value of the property.
         /// </summary>
+        /// <value>
+        /// The new value of the property.
+        /// </value>
         public object NewValue { get; private set; }
 
         /// <summary>
         /// Gets the priority of the binding that produced the value.
         /// </summary>
+        /// <value>
+        /// The priority of the binding that produced the value.
+        /// </value>
         public BindingPriority Priority { get; private set; }
     }
 }

Perspex.Base/PerspexProperty`1.cs

@@ -0,0 +1,80 @@
+// -----------------------------------------------------------------------
+// <copyright file="PerspexProperty`1.cs" company="Steven Kirk">
+// Copyright 2014 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex
+{
+    using System;
+
+    /// <summary>
+    /// A typed perspex property.
+    /// </summary>
+    /// <typeparam name="TValue">The value type of the property.</typeparam>
+    public class PerspexProperty<TValue> : PerspexProperty
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PerspexProperty{TValue}"/> class.
+        /// </summary>
+        /// <param name="name">The name of the property.</param>
+        /// <param name="ownerType">The type of the class that registers the property.</param>
+        /// <param name="defaultValue">The default value of the property.</param>
+        /// <param name="inherits">Whether the property inherits its value.</param>
+        /// <param name="defaultBindingMode">The default binding mode for the property.</param>
+        /// <param name="coerce">A coercion function.</param>
+        /// <param name="isAttached">Whether the property is an attached property.</param>
+        public PerspexProperty(
+            string name,
+            Type ownerType,
+            TValue defaultValue = default(TValue),
+            bool inherits = false,
+            BindingMode defaultBindingMode = BindingMode.Default,
+            Func<PerspexObject, TValue, TValue> coerce = null,
+            bool isAttached = false)
+            : base(
+                name,
+                typeof(TValue),
+                ownerType,
+                defaultValue,
+                inherits,
+                defaultBindingMode,
+                Convert(coerce),
+                isAttached)
+        {
+            Contract.Requires<NullReferenceException>(name != null);
+            Contract.Requires<NullReferenceException>(ownerType != null);
+        }
+
+        /// <summary>
+        /// Registers the property on another type.
+        /// </summary>
+        /// <typeparam name="TOwner">The type of the additional owner.</typeparam>
+        /// <returns>The property.</returns>
+        public PerspexProperty<TValue> AddOwner<TOwner>()
+        {
+            PerspexObject.Register(typeof(TOwner), this);
+            return this;
+        }
+
+        /// <summary>
+        /// Gets the default value for the property on the specified type.
+        /// </summary>
+        /// <typeparam name="T">The type.</typeparam>
+        /// <returns>The default value.</returns>
+        public TValue GetDefaultValue<T>()
+        {
+            return (TValue)this.GetDefaultValue(typeof(T));
+        }
+
+        /// <summary>
+        /// Converts from a typed coercion function to an untyped.
+        /// </summary>
+        /// <param name="f">The typed coercion function.</param>
+        /// <returns>Te untyped coercion function.</returns>
+        private static Func<PerspexObject, object, object> Convert(Func<PerspexObject, TValue, TValue> f)
+        {
+            return f != null ? (o, v) => f(o, (TValue)v) : (Func<PerspexObject, object, object>)null;
+        }
+    }
+}

Perspex.Base/Platform/IPlatformThreadingInterface.cs

@@ -7,15 +7,16 @@
 namespace Perspex.Platform
 {
     using System;
-    using System.Threading;
-    using System.Threading.Tasks;
-    using Perspex.Threading;
 
     /// <summary>
     /// Provides platform-specific services relating to threading.
     /// </summary>
     public interface IPlatformThreadingInterface
     {
+        /// <summary>
+        /// Checks whether there are messages waiting to be processed.
+        /// </summary>
+        /// <returns>True if there are messages waiting, otherwise false.</returns>
         bool HasMessages();
 
         /// <summary>

Perspex.Base/PriorityBindingEntry.cs

@@ -0,0 +1,111 @@
+// -----------------------------------------------------------------------
+// <copyright file="PriorityBindingEntry.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex
+{
+    using System;
+
+    /// <summary>
+    /// A registered binding in a <see cref="PriorityValue"/>.
+    /// </summary>
+    internal class PriorityBindingEntry : IDisposable
+    {
+        /// <summary>
+        /// The binding subscription.
+        /// </summary>
+        private IDisposable subscription;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PriorityBindingEntry"/> class.
+        /// </summary>
+        /// <param name="index">
+        /// The binding index. Later bindings should have higher indexes.
+        /// </param>
+        public PriorityBindingEntry(int index)
+        {
+            this.Index = index;
+        }
+
+        /// <summary>
+        /// Gets the observable associated with the entry.
+        /// </summary>
+        public IObservable<object> Observable { get; private set; }
+
+        /// <summary>
+        /// Gets a description of the binding.
+        /// </summary>
+        public string Description
+        {
+            get;
+            private set;
+        }
+
+        /// <summary>
+        /// Gets the binding entry index. Later bindings will have higher indexes.
+        /// </summary>
+        public int Index
+        {
+            get;
+        }
+
+        /// <summary>
+        /// The current value of the binding.
+        /// </summary>
+        public object Value
+        {
+            get;
+            private set;
+        }
+
+        /// <summary>
+        /// Starts listening to the binding.
+        /// </summary>
+        /// <param name="binding">The binding.</param>
+        /// <param name="changed">Called when the binding changes.</param>
+        /// <param name="completed">Called when the binding completes.</param>
+        public void Start(
+            IObservable<object> binding,
+            Action<PriorityBindingEntry> changed,
+            Action<PriorityBindingEntry> completed)
+        {
+            Contract.Requires<ArgumentNullException>(binding != null);
+            Contract.Requires<ArgumentNullException>(changed != null);
+            Contract.Requires<ArgumentNullException>(completed != null);
+
+            if (this.subscription != null)
+            {
+                throw new Exception("PriorityValue.Entry.Start() called more than once.");
+            }
+
+            this.Observable = binding;
+            this.Value = PerspexProperty.UnsetValue;
+
+            if (binding is IDescription)
+            {
+                this.Description = ((IDescription)binding).Description;
+            }
+
+            this.subscription = binding.Subscribe(
+                value =>
+                {
+                    this.Value = value;
+                    changed(this);
+                },
+                () => completed(this));
+        }
+
+        /// <summary>
+        /// Ends the binding subscription.
+        /// </summary>
+        public void Dispose()
+        {
+            if (this.subscription != null)
+            {
+                this.subscription.Dispose();
+            }
+        }
+    }
+}

Perspex.Base/PriorityLevel.cs

@@ -0,0 +1,210 @@
+// -----------------------------------------------------------------------
+// <copyright file="PriorityLevel.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Reactive.Disposables;
+
+    /// <summary>
+    /// Determines how the current binding is selected for a <see cref="PriorityLevel"/>.
+    /// </summary>
+    internal enum LevelPrecedenceMode
+    {
+        /// <summary>
+        /// The latest fired binding is used as the current value.
+        /// </summary>
+        Latest,
+
+        /// <summary>
+        /// The latest added binding is used as the current value.
+        /// </summary>
+        Newest,
+    }
+
+    /// <summary>
+    /// Stores bindings for a priority level in a <see cref="PriorityValue"/>.
+    /// </summary>
+    /// <remarks>
+    /// <para>
+    /// Each priority level in a <see cref="PriorityValue"/> has a current <see cref="Value"/>,
+    /// a list of <see cref="Bindings"/> and a <see cref="DirectValue"/>. When there are no
+    /// bindings present, or all bindings return <see cref="PerspexProperty.UnsetValue"/> then
+    /// <code>Value</code> will equal <code>DirectValue</code>.
+    /// </para>
+    /// <para>
+    /// When there are bindings present, then the latest added binding that doesn't return
+    /// <code>UnsetValue</code> will take precedence. The active binding is returned by the
+    /// <see cref="ActiveBindingIndex"/> property (which refers to the active binding's
+    /// <see cref="PriorityBindingEntry.Index"/> property rather than the index in
+    /// <code>Bindings</code>).
+    /// </para>
+    /// <para>
+    /// If <code>DirectValue</code> is set while a binding is active, then it will replace the
+    /// current value until the active binding fires again.
+    /// </para>
+    /// </remarks>
+    internal class PriorityLevel
+    {
+        /// <summary>
+        /// Method called when current value changes.
+        /// </summary>
+        private Action<PriorityLevel> changed;
+
+        /// <summary>
+        /// The current direct value.
+        /// </summary>
+        private object directValue;
+
+        /// <summary>
+        /// The index of the next <see cref="PriorityBindingEntry"/>.
+        /// </summary>
+        private int nextIndex;
+
+        private LevelPrecedenceMode mode;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PriorityLevel"/> class.
+        /// </summary>
+        /// <param name="priority">The priority.</param>
+        /// <param name="mode">The precedence mode.</param>
+        /// <param name="changed">A method to be called when the current value changes.</param>
+        public PriorityLevel(
+            int priority,
+            LevelPrecedenceMode mode,
+            Action<PriorityLevel> changed)
+        {
+            Contract.Requires<ArgumentNullException>(changed != null);
+
+            this.mode = mode;
+            this.changed = changed;
+            this.Priority = priority;
+            this.Value = this.directValue = PerspexProperty.UnsetValue;
+            this.ActiveBindingIndex = -1;
+            this.Bindings = new LinkedList<PriorityBindingEntry>();
+        }
+
+        /// <summary>
+        /// Gets the priority of this level.
+        /// </summary>
+        public int Priority { get; }
+
+        /// <summary>
+        /// Gets or sets the direct value for this priority level.
+        /// </summary>
+        public object DirectValue
+        {
+            get
+            {
+                return this.directValue;
+            }
+
+            set
+            {
+                this.Value = this.directValue = value;
+                this.changed(this);
+            }
+        }
+
+        /// <summary>
+        /// Gets the current binding for the priority level.
+        /// </summary>
+        public object Value { get; private set; }
+
+        /// <summary>
+        /// Gets the <see cref="PriorityBindingEntry.Index"/> value of the active binding, or -1
+        /// if no binding is active.
+        /// </summary>
+        public int ActiveBindingIndex { get; private set; }
+
+        /// <summary>
+        /// Gets the bindings for the priority level.
+        /// </summary>
+        public LinkedList<PriorityBindingEntry> Bindings { get; }
+
+        /// <summary>
+        /// Adds a binding.
+        /// </summary>
+        /// <param name="binding">The binding to add.</param>
+        /// <returns>A disposable used to remove the binding.</returns>
+        public IDisposable Add(IObservable<object> binding)
+        {
+            Contract.Requires<ArgumentNullException>(binding != null);
+
+            var entry = new PriorityBindingEntry(this.nextIndex++);
+            var node = this.Bindings.AddFirst(entry);
+
+            entry.Start(binding, this.Changed, this.Completed);
+
+            return Disposable.Create(() =>
+            {
+                this.Bindings.Remove(node);
+
+                if (entry.Index >= this.ActiveBindingIndex)
+                {
+                    this.ActivateFirstBinding();
+                }
+            });
+        }
+
+        /// <summary>
+        /// Invoked when an entry in <see cref="Bindings"/> changes value.
+        /// </summary>
+        /// <param name="entry">The entry that changed.</param>
+        private void Changed(PriorityBindingEntry entry)
+        {
+            if (this.mode == LevelPrecedenceMode.Latest || entry.Index >= this.ActiveBindingIndex)
+            {
+                if (entry.Value != PerspexProperty.UnsetValue)
+                {
+                    this.Value = entry.Value;
+                    this.ActiveBindingIndex = entry.Index;
+                    this.changed(this);
+                }
+                else
+                {
+                    this.ActivateFirstBinding();
+                }
+            }
+        }
+
+        /// <summary>
+        /// Invoked when an entry in <see cref="Bindings"/> completes.
+        /// </summary>
+        /// <param name="entry">The entry that completed.</param>
+        private void Completed(PriorityBindingEntry entry)
+        {
+            this.Bindings.Remove(entry);
+
+            if (entry.Index >= this.ActiveBindingIndex)
+            {
+                this.ActivateFirstBinding();
+            }
+        }
+
+        /// <summary>
+        /// Activates the first binding that has a value.
+        /// </summary>
+        private void ActivateFirstBinding()
+        {
+            foreach (var binding in this.Bindings)
+            {
+                if (binding.Value != PerspexProperty.UnsetValue)
+                {
+                    this.Value = binding.Value;
+                    this.ActiveBindingIndex = binding.Index;
+                    this.changed(this);
+                    return;
+                }
+            }
+
+            this.Value = this.DirectValue;
+            this.ActiveBindingIndex = -1;
+            this.changed(this);
+        }
+    }
+}

Perspex.Base/PriorityValue.cs

@@ -8,23 +8,25 @@ namespace Perspex
 {
     using System;
     using System.Collections.Generic;
-    using System.Reactive.Disposables;
+    using System.Linq;
     using System.Reactive.Subjects;
     using System.Reflection;
+    using System.Text;
+    using Perspex.Utilities;
 
     /// <summary>
     /// Maintains a list of prioritised bindings together with a current value.
     /// </summary>
     /// <remarks>
-    /// Bindings, in the form of <see cref="IObservable<object>"/>s are added to the object using
+    /// Bindings, in the form of <see cref="IObservable{object}"/>s are added to the object using
     /// the <see cref="Add"/> method. With the observable is passed a priority, where lower values
     /// represent higher priorites. The current <see cref="Value"/> is selected from the highest
     /// priority binding that doesn't return <see cref="PerspexProperty.UnsetValue"/>. Where there
     /// are multiple bindings registered with the same priority, the most recently added binding
-    /// has a higher priority. Each time the value changes to a distinct new value, the
+    /// has a higher priority. Each time the value changes, the <see cref="Changed"/> observable is
-    /// <see cref="Changed"/> observable is fired with the old and new values.
+    /// fired with the old and new values.
     /// </remarks>
-    public class PriorityValue
+    internal class PriorityValue
     {
         /// <summary>
         /// The name of the property.
@@ -37,9 +39,9 @@ namespace Perspex
         private Type valueType;
 
         /// <summary>
-        /// The currently registered binding entries.
+        /// The currently registered bindings organised by priority.
         /// </summary>
-        private LinkedList<BindingEntry> bindings = new LinkedList<BindingEntry>();
+        private Dictionary<int, PriorityLevel> levels = new Dictionary<int, PriorityLevel>();
 
         /// <summary>
         /// The changed observable.
@@ -51,6 +53,9 @@ namespace Perspex
         /// </summary>
         private object value;
 
+        /// <summary>
+        /// The function used to coerce the value, if any.
+        /// </summary>
         private Func<object, object> coerce;
 
         /// <summary>
@@ -69,8 +74,11 @@ namespace Perspex
         }
 
         /// <summary>
-        /// Fired whenever the current <see cref="Value"/> changes to a new distinct value.
+        /// Fired whenever the current <see cref="Value"/> changes.
         /// </summary>
+        /// <remarks>
+        /// The old and new values may be the same, this class does not check for distinct values.
+        /// </remarks>
         public IObservable<Tuple<object, object>> Changed
         {
             get { return this.changed; }
@@ -93,39 +101,6 @@ namespace Perspex
             private set;
         }
 
-        /// <summary>
-        /// Checks whether a value is valid for a type.
-        /// </summary>
-        /// <param name="value"></param>
-        /// <param name="propertyType"></param>
-        /// <returns></returns>
-        public static bool IsValidValue(object value, Type propertyType)
-        {
-            TypeInfo type = propertyType.GetTypeInfo();
-
-            if (value == PerspexProperty.UnsetValue)
-            {
-                return true;
-            }
-            else if (value == null)
-            {
-                if (type.IsValueType && 
-                    (!type.IsGenericType || !(type.GetGenericTypeDefinition() == typeof(Nullable<>))))
-                {
-                    return false;
-                }
-            }
-            else
-            {
-                if (!type.IsAssignableFrom(value.GetType().GetTypeInfo()))
-                {
-                    return false;
-                }
-            }
-
-            return true;
-        }
-
         /// <summary>
         /// Adds a new binding.
         /// </summary>
@@ -136,110 +111,72 @@ namespace Perspex
         /// </returns>
         public IDisposable Add(IObservable<object> binding, int priority)
         {
-            BindingEntry entry = new BindingEntry();
+            return this.GetLevel(priority).Add(binding);
-            LinkedListNode<BindingEntry> insert = this.bindings.First;
-
-            while (insert != null && insert.Value.Priority < priority)
-            {
-                insert = insert.Next;
-            }
-
-            if (insert == null)
-            {
-                this.bindings.AddLast(entry);
-            }
-            else
-            {
-                this.bindings.AddBefore(insert, entry);
-            }
-
-            entry.Start(binding, priority, this.EntryChanged, this.EntryCompleted);
-
-            return Disposable.Create(() =>
-            {
-                this.Remove(entry);
-            });
         }
 
         /// <summary>
-        /// Adds a new binding, replacing all those of the same priority.
+        /// Sets the direct value for a specified priority.
         /// </summary>
-        /// <param name="binding">The binding.</param>
+        /// <param name="value">The value.</param>
-        /// <param name="priority">The binding priority.</param>
+        /// <param name="priority">The priority</param>
-        /// <returns>
+        public void SetDirectValue(object value, int priority)
-        /// A disposable that will remove the binding.
-        /// </returns>
-        public IDisposable Replace(IObservable<object> binding, int priority)
         {
-            BindingEntry entry = new BindingEntry();
+            this.GetLevel(priority).DirectValue = value;
-            LinkedListNode<BindingEntry> insert = this.bindings.First;
+        }
-
-            while (insert != null && insert.Value.Priority < priority)
-            {
-                insert = insert.Next;
-            }
-
-            while (insert != null && insert.Value.Priority == priority)
-            {
-                LinkedListNode<BindingEntry> next = insert.Next;
-                insert.Value.Dispose();
-                this.bindings.Remove(insert);
-                insert = next;
-            }
 
-            if (insert == null)
+        /// <summary>
-            {
+        /// Gets the currently active bindings on this object.
-                this.bindings.AddLast(entry);
+        /// </summary>
-            }
+        /// <returns>An enumerable collection of bindings.</returns>
-            else
+        public IEnumerable<PriorityBindingEntry> GetBindings()
+        {
+            foreach (var level in this.levels)
             {
-                this.bindings.AddBefore(insert, entry);
+                foreach (var binding in level.Value.Bindings)
+                {
+                    yield return binding;
+                }
             }
-
-            entry.Start(binding, priority, this.EntryChanged, this.EntryCompleted);
-
-            return Disposable.Create(() =>
-            {
-                this.Remove(entry);
-            });
         }
 
         /// <summary>
-        /// Removes all bindings with the specified priority.
+        /// Returns diagnostic string that can help the user debug the bindings in effect on
+        /// this object.
         /// </summary>
-        /// <param name="priority">The priority.</param>
+        /// <returns>A diagnostic string.</returns>
-        public void Clear(int priority)
+        public string GetDiagnostic()
         {
-            LinkedListNode<BindingEntry> item = this.bindings.First;
+            var b = new StringBuilder();
-            bool removed = false;
+            var first = true;
 
-            while (item != null && item.Value.Priority <= priority)
+            foreach (var level in this.levels)
             {
-                LinkedListNode<BindingEntry> next = item.Next;
+                if (!first)
-
-                if (item.Value.Priority == priority)
                 {
-                    item.Value.Dispose();
+                    b.AppendLine();
-                    this.bindings.Remove(item);
-                    removed = true;
                 }
 
-                item = next;
+                b.Append(this.ValuePriority == level.Key ? "*" : string.Empty);
-            }
+                b.Append("Priority ");
+                b.Append(level.Key);
+                b.Append(": ");
+                b.AppendLine(level.Value.Value?.ToString() ?? "(null)");
+                b.AppendLine("--------");
+                b.Append("Direct: ");
+                b.AppendLine(level.Value.DirectValue?.ToString() ?? "(null)");
 
-            if (removed && priority <= this.ValuePriority)
+                foreach (var binding in level.Value.Bindings)
-            {
+                {
-                this.UpdateValue();
+                    b.Append(level.Value.ActiveBindingIndex == binding.Index ? "*" : string.Empty);
+                    b.Append(binding.Description ?? binding.Observable.GetType().Name);
+                    b.Append(": ");
+                    b.AppendLine(binding.Value?.ToString() ?? "(null)");
+                }
+
+                first = false;
             }
-        }
 
-        /// <summary>
+            return b.ToString();
-        /// Gets the currently active bindings on this object.
-        /// </summary>
-        /// <returns>An enumerable collection of bindings.</returns>
-        public IEnumerable<BindingEntry> GetBindings()
-        {
-            return this.bindings;
         }
 
         /// <summary>
@@ -249,185 +186,87 @@ namespace Perspex
         {
             if (this.coerce != null)
             {
-                this.SetValue(this.Value, this.ValuePriority);
+                PriorityLevel level;
+
+                if (this.levels.TryGetValue(this.ValuePriority, out level))
+                {
+                    this.UpdateValue(level.Value, level.Priority);
+                }
             }
         }
 
         /// <summary>
-        /// Throws an exception if <paramref name="value"/> is invalid.
+        /// Gets the <see cref="PriorityLevel"/> with the specified priority, creating it if it
+        /// doesn't already exist.
         /// </summary>
-        /// <param name="value">The value.</param>
+        /// <param name="priority">The priority.</param>
-        private void VerifyValidValue(object value)
+        /// <returns>The priority level.</returns>
+        private PriorityLevel GetLevel(int priority)
         {
-            if (!IsValidValue(value, this.valueType))
+            PriorityLevel result;
+
+            if (!this.levels.TryGetValue(priority, out result))
             {
-                throw new InvalidOperationException(string.Format(
+                var mode = (LevelPrecedenceMode)(priority % 2);
-                    "Invalid value for Property '{0}': {1} ({2})",
+                result = new PriorityLevel(priority, mode, this.ValueChanged);
-                    this.name,
+                this.levels.Add(priority, result);
-                    value,
-                    value.GetType().FullName));
             }
+
+            return result;
         }
 
         /// <summary>
-        /// Called when a binding's value changes.
+        /// Updates the current <see cref="Value"/> and notifies all subscibers.
         /// </summary>
-        /// <param name="changed">The changed entry.</param>
+        /// <param name="value">The value to set.</param>
-        private void EntryChanged(BindingEntry changed)
+        /// <param name="priority">The priority level that the value came from.</param>
+        private void UpdateValue(object value, int priority)
         {
-            if (changed.Priority <= this.ValuePriority)
+            if (!TypeUtilities.TryCast(this.valueType, value, out value))
             {
-                this.UpdateValue();
+                throw new InvalidOperationException(string.Format(
+                    "Invalid value for Property '{0}': {1} ({2})",
+                    this.name,
+                    value,
+                    value?.GetType().FullName ?? "(null)"));
             }
-        }
-
-        /// <summary>
-        /// Called when a binding completes.
-        /// </summary>
-        /// <param name="changed">The completed entry.</param>
-        private void EntryCompleted(BindingEntry entry)
-        {
-            this.Remove(entry);
-        }
 
-        /// <summary>
+            var old = this.value;
-        /// Sets the current value and notifies all observers.
-        /// </summary>
-        /// <param name="value">The new value.</param>
-        /// <param name="priority">The priority of the binding which produced the value.</param>
-        private void SetValue(object value, int priority)
-        {
-            VerifyValidValue(value);
 
             if (this.coerce != null)
             {
                 value = this.coerce(value);
-                VerifyValidValue(value);
             }
 
-            object old = this.value;
-
             this.ValuePriority = priority;
-
+            this.value = value;
-            if (!EqualityComparer<object>.Default.Equals(old, value))
+            this.changed.OnNext(Tuple.Create(old, this.value));
-            {
-                this.value = value;
-                this.changed.OnNext(Tuple.Create(old, value));
-            }
         }
 
         /// <summary>
-        /// Removes the specified binding entry and updates the current value.
+        /// Called when the value for a priority level changes.
         /// </summary>
-        /// <param name="entry">The binding entry to remove.</param>
+        /// <param name="level">The priority level of the changed entry.</param>
-        private void Remove(BindingEntry entry)
+        private void ValueChanged(PriorityLevel level)
         {
-            entry.Dispose();
+            if (level.Priority <= this.ValuePriority)
-            this.bindings.Remove(entry);
-            this.UpdateValue();
-        }
-
-        /// <summary>
-        /// Updates the current value.
-        /// </summary>
-        private void UpdateValue()
-        {
-            foreach (BindingEntry entry in this.bindings)
-            {
-                if (entry.Value != PerspexProperty.UnsetValue)
-                {
-                    this.SetValue(entry.Value, entry.Priority);
-                    return;
-                }
-            }
-
-            this.SetValue(PerspexProperty.UnsetValue, int.MaxValue);
-        }
-
-        /// <summary>
-        /// A registered binding.
-        /// </summary>
-        public class BindingEntry : IDisposable
-        {
-            /// <summary>
-            /// The binding subscription.
-            /// </summary>
-            private IDisposable subscription;
-
-            /// <summary>
-            /// Gets a description of the binding.
-            /// </summary>
-            public string Description
-            {
-                get;
-                private set;
-            }
-
-            /// <summary>
-            /// The priority of the binding.
-            /// </summary>
-            public int Priority
-            {
-                get;
-                private set;
-            }
-
-            /// <summary>
-            /// The current value of the binding.
-            /// </summary>
-            public object Value
             {
-                get;
+                if (level.Value != PerspexProperty.UnsetValue)
-                private set;
-            }
-
-            /// <summary>
-            /// Starts listening to the specified binding.
-            /// </summary>
-            /// <param name="binding">The binding.</param>
-            /// <param name="priority">The binding priority.</param>
-            /// <param name="changed">Called when the binding changes.</param>
-            /// <param name="completed">Called when the binding completes.</param>
-            public void Start(
-                IObservable<object> binding,
-                int priority,
-                Action<BindingEntry> changed,
-                Action<BindingEntry> completed)
-            {
-                Contract.Requires<ArgumentNullException>(binding != null);
-                Contract.Requires<ArgumentNullException>(changed != null);
-                Contract.Requires<ArgumentNullException>(completed != null);
-
-                if (this.subscription != null)
                 {
-                    throw new Exception("PriorityValue.Entry.Start() called more than once.");
+                    this.UpdateValue(level.Value, level.Priority);
                 }
-
+                else
-                this.Priority = priority;
-                this.Value = PerspexProperty.UnsetValue;
-
-                if (binding is IDescription)
                 {
-                    this.Description = ((IDescription)binding).Description;
+                    foreach (var i in this.levels.Values.OrderBy(x => x.Priority))
-                }
-
-                this.subscription = binding.Subscribe(
-                    value =>
                     {
-                        this.Value = value;
+                        if (i.Value != PerspexProperty.UnsetValue)
-                        changed(this);
+                        {
-                    },
+                            this.UpdateValue(i.Value, i.Priority);
-                    () => completed(this));
+                            return;
-            }
+                        }
-
+                    }
-            /// <summary>
+
-            /// Ends the binding subscription.
+                    this.UpdateValue(PerspexProperty.UnsetValue, int.MaxValue);
-            /// </summary>
-            public void Dispose()
-            {
-                if (this.subscription != null)
-                {
-                    this.subscription.Dispose();
                 }
             }
         }

Perspex.Base/Properties/AssemblyInfo.cs

@@ -6,6 +6,7 @@
 
 using System.Reflection;
 using System.Resources;
+using System.Runtime.CompilerServices;
 
 // General Information about an assembly is controlled through the following 
 // set of attributes. Change these attribute values to modify the information
@@ -32,3 +33,5 @@ using System.Resources;
 // [assembly: AssemblyVersion("1.0.*")]
 [assembly: AssemblyVersion("1.0.0.0")]
 [assembly: AssemblyFileVersion("1.0.0.0")]
+
+[assembly:InternalsVisibleTo("Perspex.Base.UnitTests")]

Perspex.Base/Reactive/PerspexObservable.cs

@@ -0,0 +1,35 @@
+// -----------------------------------------------------------------------
+// <copyright file="PerspexObservable.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Reactive
+{
+    using System;
+    using System.Reactive;
+    using System.Reactive.Disposables;
+
+    public sealed class PerspexObservable<T> : ObservableBase<T>, IDescription
+    {
+        private readonly Func<IObserver<T>, IDisposable> subscribe;
+
+        public PerspexObservable(Func<IObserver<T>, IDisposable> subscribe, string description)
+        {
+            if (subscribe == null)
+            {
+                throw new ArgumentNullException("subscribe");
+            }
+
+            this.subscribe = subscribe;
+            this.Description = description;
+        }
+
+        public string Description { get; }
+
+        protected override IDisposable SubscribeCore(IObserver<T> observer)
+        {
+            return this.subscribe(observer) ?? Disposable.Empty;
+        }
+    }
+}

Perspex.Base/Threading/PerspexScheduler.cs

@@ -12,20 +12,17 @@ namespace Perspex.Threading
 
     public class PerspexScheduler : LocalScheduler
     {
-        private static readonly PerspexScheduler instance = new PerspexScheduler();
+        public static readonly PerspexScheduler Instance = new PerspexScheduler();
-
-        public static PerspexScheduler Instance
-        {
-            get { return instance; }
-        }
 
         public override IDisposable Schedule<TState>(TState state, TimeSpan dueTime, Func<IScheduler, TState, IDisposable> action)
         {
-            return DispatcherTimer.Run(() => 
+            return DispatcherTimer.Run(
-            {
+                () => 
-                action(this, state);
+                {
-                return false;
+                    action(this, state);
-            }, dueTime);
+                    return false;
+                }, 
+                dueTime);
         }
     }
 }

Perspex.Base/Utilities/TypeUtilities.cs

@@ -0,0 +1,84 @@
+// -----------------------------------------------------------------------
+// <copyright file="TypeUtilities.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Utilities
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using System.Reflection;
+
+    /// <summary>
+    /// Provides utilities for working with types at runtime.
+    /// </summary>
+    internal static class TypeUtilities
+    {
+        private static readonly Dictionary<Type, List<Type>> Conversions = new Dictionary<Type, List<Type>>()
+        {
+            { typeof(decimal), new List<Type> { typeof(sbyte), typeof(byte), typeof(short), typeof(ushort), typeof(int), typeof(uint), typeof(long), typeof(ulong), typeof(char) } },
+            { typeof(double), new List<Type> { typeof(sbyte), typeof(byte), typeof(short), typeof(ushort), typeof(int), typeof(uint), typeof(long), typeof(ulong), typeof(char), typeof(float) } },
+            { typeof(float), new List<Type> { typeof(sbyte), typeof(byte), typeof(short), typeof(ushort), typeof(int), typeof(uint), typeof(long), typeof(ulong), typeof(char), typeof(float) } },
+            { typeof(ulong), new List<Type> { typeof(byte), typeof(ushort), typeof(uint), typeof(char) } },
+            { typeof(long), new List<Type> { typeof(sbyte), typeof(byte), typeof(short), typeof(ushort), typeof(int), typeof(uint), typeof(char) } },
+            { typeof(uint), new List<Type> { typeof(byte), typeof(ushort), typeof(char) } },
+            { typeof(int), new List<Type> { typeof(sbyte), typeof(byte), typeof(short), typeof(ushort), typeof(char) } },
+            { typeof(ushort), new List<Type> { typeof(byte), typeof(char) } },
+            { typeof(short), new List<Type> { typeof(byte) } }
+        };
+
+        /// <summary>
+        /// Try to cast a value to a type, using implicit conversions if possible.
+        /// </summary>
+        /// <param name="to">The type to cast to.</param>
+        /// <param name="value">The value to cast.</param>
+        /// <param name="result">If sucessful, contains the cast value.</param>
+        /// <returns>True if the cast was sucessful, otherwise false.</returns>
+        public static bool TryCast(Type to, object value, out object result)
+        {
+            Contract.Requires<NullReferenceException>(to != null);
+
+            if (value == null)
+            {
+                var t = to.GetTypeInfo();
+                result = null;
+                return !t.IsValueType || (t.IsGenericType && (t.GetGenericTypeDefinition() == typeof(Nullable<>)));
+            }
+
+            var from = value.GetType();
+
+            if (value == PerspexProperty.UnsetValue)
+            {
+                result = value;
+                return true;
+            }
+            else if (to.GetTypeInfo().IsAssignableFrom(from.GetTypeInfo()))
+            {
+                result = value;
+                return true;
+            }
+            else if (Conversions.ContainsKey(to) && Conversions[to].Contains(from))
+            {
+                result = Convert.ChangeType(value, to);
+                return true;
+            }
+            else
+            {
+                var cast = from.GetTypeInfo()
+                    .GetDeclaredMethods("op_Implicit")
+                    .FirstOrDefault(m => m.ReturnType == to);
+
+                if (cast != null)
+                {
+                    result = cast.Invoke(null, new[] { value });
+                    return true;
+                }
+            }
+
+            result = null;
+            return false;
+        }
+    }
+}

Perspex.Base/packages.config

@@ -1,10 +1,11 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="Rx-Core" version="2.2.5" targetFramework="portable-net45+win" />
+  <package id="Rx-Core" version="2.2.5" targetFramework="portable-net45+win8" userInstalled="true" />
-  <package id="Rx-Interfaces" version="2.2.5" targetFramework="portable-net45+win" />
+  <package id="Rx-Interfaces" version="2.2.5" targetFramework="portable-net45+win8" userInstalled="true" />
-  <package id="Rx-Linq" version="2.2.5" targetFramework="portable-net45+win" />
+  <package id="Rx-Linq" version="2.2.5" targetFramework="portable-net45+win8" userInstalled="true" />
-  <package id="Rx-Main" version="2.2.5" targetFramework="portable-net45+win" />
+  <package id="Rx-Main" version="2.2.5" targetFramework="portable-net45+win8" userInstalled="true" />
-  <package id="Rx-PlatformServices" version="2.2.5" targetFramework="portable-net45+win" />
+  <package id="Rx-PlatformServices" version="2.2.5" targetFramework="portable-net45+win8" userInstalled="true" />
-  <package id="Splat" version="1.6.1" targetFramework="portable-net45+win" />
+  <package id="Serilog" version="1.5.5" targetFramework="portable45-net45+win8" userInstalled="true" />
-  <package id="StyleCop.MSBuild" version="4.7.49.0" targetFramework="portable-net45+win" developmentDependency="true" />
+  <package id="Splat" version="1.6.2" targetFramework="portable45-net45+win8" userInstalled="true" />
+  <package id="StyleCop.Analyzers" version="1.0.0-alpha008" targetFramework="portable45-net45+win8" userInstalled="true" />
 </packages>

Perspex.Controls/Border.cs

@@ -51,7 +51,7 @@ namespace Perspex.Controls
             Brush background = this.Background;
             Brush borderBrush = this.BorderBrush;
             double borderThickness = this.BorderThickness;
-            Rect rect = new Rect(this.Bounds.Size).Deflate(this.BorderThickness / 2);
+            Rect rect = new Rect(this.Bounds.Size).Deflate(this.BorderThickness);
 
             if (background != null)
             {
@@ -85,10 +85,12 @@ namespace Perspex.Controls
             if (content != null)
             {
                 content.Measure(availableSize.Deflate(padding));
-                return content.DesiredSize.Value.Inflate(padding);
+                return content.DesiredSize.Inflate(padding);
+            }
+            else
+            {
+                return new Size(padding.Left + padding.Right, padding.Bottom + padding.Top);
             }
-
-            return new Size();
         }
     }
 }

Perspex.Controls/Button.cs

@@ -100,6 +100,39 @@ namespace Perspex.Controls
             }
         }
 
+        protected override void OnKeyDown(KeyEventArgs e)
+        {
+            if (e.Key == Key.Enter)
+            {
+                this.RaiseClickEvent();
+                e.Handled = true;
+            }
+            else if (e.Key == Key.Space)
+            {
+                if (this.ClickMode == ClickMode.Press)
+                {
+                    this.RaiseClickEvent();
+                }
+
+                e.Handled = true;
+            }
+
+            base.OnKeyDown(e);
+        }
+
+        protected override void OnKeyUp(KeyEventArgs e)
+        {
+            if (e.Key == Key.Space)
+            {
+                if (this.ClickMode == ClickMode.Release)
+                {
+                    this.RaiseClickEvent();
+                }
+
+                e.Handled = true;
+            }
+        }
+
         protected override void OnDetachedFromVisualTree(IRenderRoot oldRoot)
         {
             base.OnDetachedFromVisualTree(oldRoot);
@@ -203,7 +236,7 @@ namespace Perspex.Controls
 
         private void ListenForDefault(IInputElement root)
         {
-            root.AddHandler(InputElement.KeyDownEvent, this.RootKeyDown, RoutingStrategies.Tunnel);
+            root.AddHandler(InputElement.KeyDownEvent, this.RootKeyDown);
         }
 
         private void StopListeningForDefault(IInputElement root)

Perspex.Controls/ColumnDefinitions.cs

@@ -6,9 +6,19 @@
 
 namespace Perspex.Controls
 {
+    using System.Linq;
     using Perspex.Collections;
+    using Perspex.Controls.Parsers;
 
     public class ColumnDefinitions : PerspexList<ColumnDefinition>
     {
+        public ColumnDefinitions()
+        {
+        }
+
+        public ColumnDefinitions(string s)
+        {
+            this.AddRange(GridLengthsParser.Parse(s).Select(x => new ColumnDefinition(x)));
+        }
     }
 }

Perspex.Controls/ContentControl.cs

@@ -28,7 +28,6 @@ namespace Perspex.Controls
 
         public ContentControl()
         {
-            this.GetObservableWithHistory(ContentProperty).Subscribe(this.SetContentParent);
         }
 
         public object Content
@@ -37,6 +36,12 @@ namespace Perspex.Controls
             set { this.SetValue(ContentProperty, value); }
         }
 
+        public ContentPresenter Presenter
+        {
+            get;
+            private set;
+        }
+
         public HorizontalAlignment HorizontalContentAlignment
         {
             get { return this.GetValue(HorizontalContentAlignmentProperty); }
@@ -59,32 +64,8 @@ namespace Perspex.Controls
             // We allow ContentControls without ContentPresenters in the template. This can be
             // useful for e.g. a simple ToggleButton that displays an image. There's no need to
             // have a ContentPresenter in the visual tree for that.
-            var presenter = this.FindTemplateChild<ContentPresenter>("contentPresenter");
+            this.Presenter = this.FindTemplateChild<ContentPresenter>("contentPresenter");
-
+            this.logicalChildren.Source = ((ILogical)this.Presenter)?.LogicalChildren;
-            if (presenter != null)
-            {
-                this.logicalChildren.Source = ((ILogical)presenter).LogicalChildren;
-            }
-            else
-            {
-                this.logicalChildren.Source = null;
-            }
-        }
-
-        private void SetContentParent(Tuple<object, object> change)
-        {
-            var control1 = change.Item1 as Control;
-            var control2 = change.Item2 as Control;
-
-            if (control1 != null)
-            {
-                control1.Parent = null;
-            }
-
-            if (control2 != null)
-            {
-                control2.Parent = this;
-            }
         }
     }
 }

Perspex.Controls/Control.cs

@@ -20,7 +20,7 @@ namespace Perspex.Controls
     using Perspex.Styling;
     using Splat;
 
-    public class Control : InputElement, ILogical, IStyleable, IStyleHost
+    public class Control : InputElement, INamed, ILogical, IStyleable, IStyleHost
     {
         public static readonly PerspexProperty<object> DataContextProperty =
             PerspexProperty.Register<Control, object>("DataContext", inherits: true);
@@ -101,7 +101,7 @@ namespace Perspex.Controls
             }
         }
 
-        public string Id
+        public string Name
         {
             get
             {
@@ -192,6 +192,40 @@ namespace Perspex.Controls
             this.RaiseEvent(ev);
         }
 
+        protected static void PseudoClass(PerspexProperty<bool> property, string className)
+        {
+            PseudoClass(property, x => x, className);
+        }
+
+        protected static void PseudoClass<T>(
+            PerspexProperty<T> property,
+            Func<T, bool> selector,
+            string className)
+        {
+            Contract.Requires<ArgumentNullException>(property != null);
+            Contract.Requires<ArgumentNullException>(selector != null);
+            Contract.Requires<ArgumentNullException>(className != null);
+            Contract.Requires<ArgumentNullException>(property != null);
+
+            if (string.IsNullOrWhiteSpace(className))
+            {
+                throw new ArgumentException("Cannot supply an empty className.");
+            }
+
+            Observable.Merge(property.Changed, property.Initialized)
+                .Subscribe(e =>
+                {
+                    if (selector((T)e.NewValue))
+                    {
+                        ((Control)e.Sender).Classes.Add(className);
+                    }
+                    else
+                    {
+                        ((Control)e.Sender).Classes.Remove(className);
+                    }
+                });
+        }
+
         protected override void OnGotFocus(GotFocusEventArgs e)
         {
             base.OnGotFocus(e);
@@ -233,40 +267,6 @@ namespace Perspex.Controls
             }
         }
 
-        protected static void PseudoClass(PerspexProperty<bool> property, string className)
-        {
-            PseudoClass(property, x => x, className);
-        }
-
-        protected static void PseudoClass<T>(
-            PerspexProperty<T> property, 
-            Func<T, bool> selector, 
-            string className)
-        {
-            Contract.Requires<ArgumentNullException>(property != null);
-            Contract.Requires<ArgumentNullException>(selector != null);
-            Contract.Requires<ArgumentNullException>(className != null);
-            Contract.Requires<ArgumentNullException>(property != null);
-
-            if (string.IsNullOrWhiteSpace(className))
-            {
-                throw new ArgumentException("Cannot supply an empty className.");
-            }
-
-            Observable.Merge(property.Changed, property.Initialized)
-                .Subscribe(e =>
-                {
-                    if (selector((T)e.NewValue))
-                    {
-                        ((Control)e.Sender).Classes.Add(className);
-                    }
-                    else
-                    {
-                        ((Control)e.Sender).Classes.Remove(className);
-                    }
-                });
-        }
-
         protected override void OnAttachedToVisualTree(IRenderRoot root)
         {
             base.OnAttachedToVisualTree(root);

Perspex.Controls/ControlExtensions.cs

@@ -17,11 +17,11 @@ namespace Perspex.Controls
 
     public static class ControlExtensions
     {
-        public static T FindControl<T>(this Control control, string id) where T : Control
+        public static T FindControl<T>(this Control control, string name) where T : Control
         {
             return control.GetLogicalDescendents()
                 .OfType<T>()
-                .FirstOrDefault(x => x.Id == id);
+                .FirstOrDefault(x => x.Name == name);
         }
     }
 }

Perspex.Controls/DataTemplate.cs

@@ -12,7 +12,7 @@ namespace Perspex.Controls
     public class DataTemplate : IDataTemplate
     {
         public static readonly DataTemplate Default =
-            new DataTemplate(typeof(object), o => new TextBlock { Text = o.ToString() });
+            new DataTemplate(typeof(object), o => (o != null) ? new TextBlock { Text = o.ToString() } : null);
 
         public DataTemplate(Func<object, Control> build)
             : this(o => true, build)
@@ -39,7 +39,9 @@ namespace Perspex.Controls
 
         public static bool IsInstance(object o, Type t)
         {
-            return t.GetTypeInfo().IsAssignableFrom(o.GetType().GetTypeInfo());
+            return (o != null) ?
+                t.GetTypeInfo().IsAssignableFrom(o.GetType().GetTypeInfo()) :
+                false;
         }
 
         bool IDataTemplate.Match(object data)

Perspex.Controls/Deck.cs

@@ -0,0 +1,65 @@
+// -----------------------------------------------------------------------
+// <copyright file="Deck.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Controls
+{
+    using System.Collections;
+    using Perspex.Animation;
+    using Perspex.Controls.Generators;
+    using Perspex.Controls.Primitives;
+    using Perspex.Controls.Utils;
+    using Perspex.Input;
+
+    /// <summary>
+    /// A selecting items control that displays a single item that fills the control.
+    /// </summary>
+    public class Deck : SelectingItemsControl
+    {
+        public static readonly PerspexProperty<IPageTransition> TransitionProperty =
+            PerspexProperty.Register<Deck, IPageTransition>("Transition");
+
+        private static readonly ItemsPanelTemplate PanelTemplate = 
+            new ItemsPanelTemplate(() => new Panel());
+
+        static Deck()
+        {
+            ItemsPanelProperty.OverrideDefaultValue(typeof(Deck), PanelTemplate);
+        }
+
+        public IPageTransition Transition
+        {
+            get { return this.GetValue(TransitionProperty); }
+            set { this.SetValue(TransitionProperty, value); }
+        }
+
+        protected override void ItemsChanged(IEnumerable oldValue, IEnumerable newValue)
+        {
+            base.ItemsChanged(oldValue, newValue);
+
+            var items = this.Items;
+
+            if (items != null && items.Count() > 0)
+            {
+                this.SelectedIndex = 0;
+            }
+        }
+
+        protected override void OnKeyDown(KeyEventArgs e)
+        {
+            // Ignore key presses.
+        }
+
+        protected override void OnPointerPressed(PointerPressEventArgs e)
+        {
+            // Ignore pointer presses.
+        }
+
+        protected override void OnTemplateApplied()
+        {
+            base.OnTemplateApplied();
+        }
+    }
+}

Perspex.Controls/Decorator.cs

@@ -80,10 +80,12 @@ namespace Perspex.Controls
             if (content != null)
             {
                 content.Measure(availableSize.Deflate(padding));
-                return content.DesiredSize.Value.Inflate(padding);
+                return content.DesiredSize.Inflate(padding);
+            }
+            else
+            {
+                return new Size(padding.Left + padding.Right, padding.Bottom + padding.Top);
             }
-
-            return new Size();
         }
     }
 }

Perspex.Controls/Generators/ItemContainerGenerator.cs

@@ -20,7 +20,7 @@ namespace Perspex.Controls.Generators
 
         private ItemContainerGeneratorState state;
 
-        public ItemContainerGenerator(ItemsControl owner)
+        public ItemContainerGenerator(Control owner)
         {
             this.Owner = owner;
         }
@@ -48,7 +48,7 @@ namespace Perspex.Controls.Generators
             }
         }
 
-        protected ItemsControl Owner
+        protected Control Owner
         {
             get;
             private set;
@@ -84,10 +84,18 @@ namespace Perspex.Controls.Generators
                 foreach (object item in items)
                 {
                     Control container = this.CreateContainerOverride(item);
-                    container.DataContext = item;
+
-                    container.TemplatedParent = null;
+                    if (container != null)
-                    this.AddInternal(item, container);
+                    {
-                    result.Add(container);
+                        if (container.DataContext == null)
+                        {
+                            container.DataContext = item;
+                        }
+
+                        container.TemplatedParent = null;
+                        this.AddInternal(item, container);
+                        result.Add(container);
+                    }
                 }
             }
             finally

Perspex.Controls/GlobalSuppressions.cs

@@ -0,0 +1,14 @@
+// -----------------------------------------------------------------------
+// <copyright file="GlobalSuppressions.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+[assembly: System.Diagnostics.CodeAnalysis.SuppressMessage(
+    "StyleCop.CSharp.MaintainabilityRules",
+    "SA1401:Fields must be private",
+    Justification = "PerspexProperty fields should not be private.")]
+[assembly: System.Diagnostics.CodeAnalysis.SuppressMessage(
+    "StyleCop.CSharp.DocumentationRules",
+    "SA1609:Property documentation must have value",
+    Justification = "This rule is fscking pointless")]

Perspex.Controls/Grid.cs

@@ -359,7 +359,7 @@ namespace Perspex.Controls
                     }
 
                     child.Measure(new Size(childSizeX, childSizeY));
-                    Size desired = child.DesiredSize.Value;
+                    Size desired = child.DesiredSize;
 
                     // Elements distribute their height based on two rules:
                     // 1) Elements with rowspan/colspan == 1 distribute their height first
@@ -420,8 +420,8 @@ namespace Perspex.Controls
         {
             int colCount = this.ColumnDefinitions.Count;
             int rowCount = this.RowDefinitions.Count;
-            int colMatrixDim = this.colMatrix.GetUpperBound(0) + 1;
+            int colMatrixDim = this.colMatrix.GetLength(0);
-            int rowMatrixDim = this.rowMatrix.GetUpperBound(0) + 1;
+            int rowMatrixDim = this.rowMatrix.GetLength(0);
 
             this.RestoreMeasureResults();
 
@@ -517,8 +517,8 @@ namespace Perspex.Controls
         private void CreateMatrices(int rowCount, int colCount)
         {
             if (this.rowMatrix == null || this.colMatrix == null ||
-                this.rowMatrix.GetUpperBound(0) != rowCount - 1 ||
+                this.rowMatrix.GetLength(0) != rowCount ||
-                this.colMatrix.GetUpperBound(0) != colCount - 1)
+                this.colMatrix.GetLength(0) != colCount)
             {
                 this.rowMatrix = new Segment[rowCount, rowCount];
                 this.colMatrix = new Segment[colCount, colCount];
@@ -527,10 +527,11 @@ namespace Perspex.Controls
 
         private void ExpandStarCols(Size availableSize)
         {
+            int matrixCount = this.colMatrix.GetLength(0);
             int columnsCount = this.ColumnDefinitions.Count;
             double width = availableSize.Width;
 
-            for (int i = 0; i < this.colMatrix.GetUpperBound(0) + 1; i++) 
+            for (int i = 0; i < matrixCount; i++) 
             {
                 if (this.colMatrix[i, i].Type == GridUnitType.Star)
                 {
@@ -542,12 +543,12 @@ namespace Perspex.Controls
                 }
             }
 
-            this.AssignSize(this.colMatrix, 0, this.colMatrix.GetUpperBound(0), ref width, GridUnitType.Star, false);
+            this.AssignSize(this.colMatrix, 0, matrixCount - 1, ref width, GridUnitType.Star, false);
             width = Math.Max(0, width);
 
             if (columnsCount > 0) 
             {
-                for (int i = 0; i < this.colMatrix.GetUpperBound(0) + 1; i++)
+                for (int i = 0; i < matrixCount; i++)
                 {
                     if (this.colMatrix[i, i].Type == GridUnitType.Star)
                     {
@@ -559,13 +560,14 @@ namespace Perspex.Controls
 
         private void ExpandStarRows(Size availableSize)
         {
+            int matrixCount = this.rowMatrix.GetLength(0);
             int rowCount = this.RowDefinitions.Count;
             double height = availableSize.Height;
 
             // When expanding star rows, we need to zero out their height before
             // calling AssignSize. AssignSize takes care of distributing the 
             // available size when there are Mins and Maxs applied.
-            for (int i = 0; i < this.rowMatrix.GetUpperBound(0) + 1; i++) 
+            for (int i = 0; i < matrixCount; i++) 
             {
                 if (this.rowMatrix[i, i].Type == GridUnitType.Star)
                 {
@@ -577,11 +579,11 @@ namespace Perspex.Controls
                 }
             }
 
-            this.AssignSize(this.rowMatrix, 0, this.rowMatrix.GetUpperBound(0), ref height, GridUnitType.Star, false);
+            this.AssignSize(this.rowMatrix, 0, matrixCount - 1, ref height, GridUnitType.Star, false);
 
             if (rowCount > 0) 
             {
-                for (int i = 0; i < this.rowMatrix.GetUpperBound(0) + 1; i++)
+                for (int i = 0; i < matrixCount; i++)
                 {
                     if (this.rowMatrix[i, i].Type == GridUnitType.Star)
                     {
@@ -703,12 +705,15 @@ namespace Perspex.Controls
                 }
             }
 
-            for (int r = 0; r < this.rowMatrix.GetUpperBound(0) + 1; r++)
+            int rowMatrixDim = this.rowMatrix.GetLength(0);
+            int colMatrixDim = this.colMatrix.GetLength(0);
+
+            for (int r = 0; r < rowMatrixDim; r++)
             {
                 this.rowMatrix[r, r].OfferedSize = this.rowMatrix[r, r].DesiredSize;
             }
 
-            for (int c = 0; c < this.colMatrix.GetUpperBound(0) + 1; c++)
+            for (int c = 0; c < colMatrixDim; c++)
             {
                 this.colMatrix[c, c].OfferedSize = this.colMatrix[c, c].DesiredSize;
             }
@@ -716,17 +721,20 @@ namespace Perspex.Controls
 
         private void SaveMeasureResults()
         {
-            for (int i = 0; i < this.rowMatrix.GetUpperBound(0) + 1; i++)
+            int rowMatrixDim = this.rowMatrix.GetLength(0);
+            int colMatrixDim = this.colMatrix.GetLength(0);
+
+            for (int i = 0; i < rowMatrixDim; i++)
             {
-                for (int j = 0; j < this.rowMatrix.GetUpperBound(0) + 1; j++)
+                for (int j = 0; j < rowMatrixDim; j++)
                 {
                     this.rowMatrix[i, j].OriginalSize = this.rowMatrix[i, j].OfferedSize;
                 }
             }
 
-            for (int i = 0; i < this.colMatrix.GetUpperBound(0); i++)
+            for (int i = 0; i < colMatrixDim; i++)
             {
-                for (int j = 0; j < this.colMatrix.GetUpperBound(0); j++)
+                for (int j = 0; j < colMatrixDim; j++)
                 {
                     this.colMatrix[i, j].OriginalSize = this.colMatrix[i, j].OfferedSize;
                 }
@@ -735,17 +743,20 @@ namespace Perspex.Controls
 
         private void RestoreMeasureResults()
         {
-            for (int i = 0; i < this.rowMatrix.GetUpperBound(0) + 1; i++)
+            int rowMatrixDim = this.rowMatrix.GetLength(0);
+            int colMatrixDim = this.colMatrix.GetLength(0);
+
+            for (int i = 0; i < rowMatrixDim; i++)
             {
-                for (int j = 0; j < this.rowMatrix.GetUpperBound(0) + 1; j++)
+                for (int j = 0; j < rowMatrixDim; j++)
                 {
                     this.rowMatrix[i, j].OfferedSize = this.rowMatrix[i, j].OriginalSize;
                 }
             }
 
-            for (int i = 0; i < this.colMatrix.GetUpperBound(0) + 1; i++)
+            for (int i = 0; i < colMatrixDim; i++)
             {
-                for (int j = 0; j < this.colMatrix.GetUpperBound(0) + 1; j++)
+                for (int j = 0; j < colMatrixDim; j++)
                 {
                     this.colMatrix[i, j].OfferedSize = this.colMatrix[i, j].OriginalSize;
                 }
@@ -802,6 +813,9 @@ namespace Perspex.Controls
         {
             public GridWalker(Grid grid, Segment[,] rowMatrix, Segment[,] colMatrix)
             {
+                int rowMatrixDim = rowMatrix.GetLength(0);
+                int colMatrixDim = colMatrix.GetLength(0);
+
                 foreach (Control child in grid.Children)
                 {
                     bool starCol = false;
@@ -809,10 +823,10 @@ namespace Perspex.Controls
                     bool autoCol = false;
                     bool autoRow = false;
 
-                    int col = Math.Min(Grid.GetColumn(child), colMatrix.GetUpperBound(0));
+                    int col = Math.Min(Grid.GetColumn(child), colMatrixDim - 1);
-                    int row = Math.Min(Grid.GetRow(child), rowMatrix.GetUpperBound(0));
+                    int row = Math.Min(Grid.GetRow(child), rowMatrixDim - 1);
-                    int colspan = Math.Min(Grid.GetColumnSpan(child), colMatrix.GetUpperBound(0));
+                    int colspan = Math.Min(Grid.GetColumnSpan(child), colMatrixDim - 1);
-                    int rowspan = Math.Min(Grid.GetRowSpan(child), rowMatrix.GetUpperBound(0));
+                    int rowspan = Math.Min(Grid.GetRowSpan(child), rowMatrixDim - 1);
 
                     for (int r = row; r < row + rowspan; r++) 
                     {

Perspex.Base/IObservableDescription.cs → Perspex.Controls/INamed.cs

@@ -1,13 +1,13 @@
 // -----------------------------------------------------------------------
-// <copyright file="IObservableDescription.cs" company="Steven Kirk">
+// <copyright file="TemplateExtensions.cs" company="Steven Kirk">
 // Copyright 2014 MIT Licence. See licence.md for more information.
 // </copyright>
 // -----------------------------------------------------------------------
 
-namespace Perspex
+namespace Perspex.Controls
 {
-    public interface IObservableDescription
+    public interface INamed
     {
-        string Description { get; }
+        string Name { get; }
     }
 }

Perspex.Controls/INavigablePanel.cs

@@ -0,0 +1,15 @@
+// -----------------------------------------------------------------------
+// <copyright file="INavigablePanel.cs" company="Steven Kirk">
+// Copyright 2014 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Controls
+{
+    using Perspex.Input;
+
+    public interface INavigablePanel
+    {
+        Control GetControl(FocusNavigationDirection direction, Control from);
+    }
+}

Perspex.Controls/ItemsControl.cs

@@ -8,7 +8,7 @@ namespace Perspex.Controls
 {
     using System;
     using System.Collections;
-    using System.ComponentModel;
+    using System.Collections.Specialized;
     using System.Diagnostics.CodeAnalysis;
     using System.Linq;
     using Perspex.Collections;
@@ -16,7 +16,8 @@ namespace Perspex.Controls
     using Perspex.Controls.Presenters;
     using Perspex.Controls.Primitives;
     using Perspex.Controls.Templates;
-    using Perspex.VisualTree;
+    using Perspex.Controls.Utils;
+    using Perspex.Styling;
 
     public class ItemsControl : TemplatedControl, ILogical
     {
@@ -35,11 +36,20 @@ namespace Perspex.Controls
         private PerspexReadOnlyListView<IVisual, ILogical> logicalChildren = 
             new PerspexReadOnlyListView<IVisual, ILogical>(x => (ILogical)x);
 
-        private ItemsPresenter presenter;
+        private IItemsPresenter presenter;
+
+        static ItemsControl()
+        {
+            ItemsProperty.Changed.Subscribe(e =>
+            {
+                var control = e.Sender as ItemsControl;
+                control?.ItemsChanged((IEnumerable)e.OldValue, (IEnumerable)e.NewValue);
+            });
+        }
 
         public ItemsControl()
         {
-            this.GetObservableWithHistory(ItemsProperty).Subscribe(this.ItemsChanged);
+            this.ItemsChanged(null, null);
         }
 
         public ItemContainerGenerator ItemContainerGenerator
@@ -76,6 +86,20 @@ namespace Perspex.Controls
             }
         }
 
+        protected IItemsPresenter Presenter
+        {
+            get
+            {
+                return this.presenter;
+            }
+
+            set
+            {
+                this.presenter = value;
+                this.logicalChildren.Source = ((IVisual)value?.Panel)?.VisualChildren;
+            }
+        }
+
         protected virtual ItemContainerGenerator CreateItemContainerGenerator()
         {
             return new ItemContainerGenerator(this);
@@ -83,24 +107,19 @@ namespace Perspex.Controls
 
         protected override void OnTemplateApplied()
         {
-            this.presenter = this.FindTemplateChild<ItemsPresenter>("itemsPresenter");
+            this.Presenter = this.FindTemplateChild<IItemsPresenter>("itemsPresenter");
-
-            if (this.presenter != null)
-            {
-                this.logicalChildren.Source = ((IVisual)this.presenter.Panel).VisualChildren;
-            }
         }
 
-        private void ItemsChanged(Tuple<IEnumerable, IEnumerable> value)
+        protected virtual void ItemsChanged(IEnumerable oldValue, IEnumerable newValue)
         {
-            INotifyPropertyChanged inpc = value.Item1 as INotifyPropertyChanged;
+            var incc = oldValue as INotifyCollectionChanged;
 
-            if (inpc != null)
+            if (incc != null)
             {
-                inpc.PropertyChanged -= this.ItemsPropertyChanged;
+                incc.CollectionChanged += this.ItemsCollectionChanged;
             }
 
-            if (value.Item2 == null || !value.Item2.OfType<object>().Any())
+            if (newValue == null || newValue.Count() == 0)
             {
                 this.Classes.Add(":empty");
             }
@@ -109,26 +128,25 @@ namespace Perspex.Controls
                 this.Classes.Remove(":empty");
             }
 
-            inpc = value.Item2 as INotifyPropertyChanged;
+            incc = newValue as INotifyCollectionChanged;
 
-            if (inpc != null)
+            if (incc != null)
             {
-                inpc.PropertyChanged += this.ItemsPropertyChanged;
+                incc.CollectionChanged += this.ItemsCollectionChanged;
             }
         }
 
-        private void ItemsPropertyChanged(object sender, PropertyChangedEventArgs e)
+        protected virtual void ItemsCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
         {
-            if (e.PropertyName == "Count")
+            var collection = sender as ICollection;
+
+            if (collection.Count == 0)
             {
-                if (((IList)sender).Count == 0)
+                this.Classes.Add(":empty");
-                {
+            }
-                    this.Classes.Add(":empty");
+            else
-                }
+            {
-                else
+                this.Classes.Remove(":empty");
-                {
-                    this.Classes.Remove(":empty");
-                }
             }
         }
     }

Perspex.Controls/ListBoxItem.cs

@@ -6,20 +6,51 @@
 
 namespace Perspex.Controls
 {
+    using System;
+    using Perspex.Controls.Primitives;
+    using Perspex.Interactivity;
+
+    /// <summary>
+    /// An selectable item in a <see cref="ListBox"/>.
+    /// </summary>
     public class ListBoxItem : ContentControl, ISelectable
     {
+        /// <summary>
+        /// Defines the <see cref="IsSelected"/> property.
+        /// </summary>
         public static readonly PerspexProperty<bool> IsSelectedProperty =
-            PerspexProperty.Register<ListBoxItem, bool>("IsSelected");
+            PerspexProperty.Register<ListBoxItem, bool>(nameof(IsSelected));
 
+        /// <summary>
+        /// Initializes static members of the <see cref="ListBoxItem"/> class.
+        /// </summary>
         static ListBoxItem()
         {
             Control.PseudoClass(IsSelectedProperty, ":selected");
+            IsSelectedProperty.Changed.Subscribe(IsSelectedChanged);
         }
 
+        /// <summary>
+        /// Gets or sets the selection state of the item.
+        /// </summary>
         public bool IsSelected
         {
             get { return this.GetValue(IsSelectedProperty); }
             set { this.SetValue(IsSelectedProperty, value); }
         }
+
+        /// <summary>
+        /// Called when the <see cref="IsSelected"/> property changes on an object.
+        /// </summary>
+        /// <param name="e">The sender.</param>
+        private static void IsSelectedChanged(PerspexPropertyChangedEventArgs e)
+        {
+            var interactive = e.Sender as IInteractive;
+
+            if (interactive != null)
+            {
+                interactive.RaiseEvent(new RoutedEventArgs(SelectingItemsControl.IsSelectedChangedEvent));
+            }
+        }
     }
 }

Perspex.Controls/Menu.cs

@@ -0,0 +1,230 @@
+// -----------------------------------------------------------------------
+// <copyright file="Menu.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Controls
+{
+    using System;
+    using System.Linq;
+    using System.Reactive.Disposables;
+    using Perspex.Input;
+    using Perspex.LogicalTree;
+    using Perspex.Rendering;
+    using Perspex.Interactivity;
+    using Perspex.Controls.Primitives;
+
+    /// <summary>
+    /// A top-level menu control.
+    /// </summary>
+    public class Menu : SelectingItemsControl, IFocusScope, IMainMenu
+    {
+        /// <summary>
+        /// Defines the default items panel used by a <see cref="Menu"/>.
+        /// </summary>
+        private static readonly ItemsPanelTemplate DefaultPanel =
+            new ItemsPanelTemplate(() => new StackPanel { Orientation = Orientation.Horizontal });
+
+        /// <summary>
+        /// Defines the <see cref="IsOpen"/> property.
+        /// </summary>
+        public static readonly PerspexProperty<bool> IsOpenProperty =
+            PerspexProperty.Register<Menu, bool>(nameof(IsOpen));
+
+        /// <summary>
+        /// Tracks event handlers added to the root of the visual tree.
+        /// </summary>
+        private IDisposable subscription;
+
+        /// <summary>
+        /// Initializes static members of the <see cref="Menu"/> class.
+        /// </summary>
+        static Menu()
+        {
+            ItemsPanelProperty.OverrideDefaultValue(typeof(Menu), DefaultPanel);
+            MenuItem.ClickEvent.AddClassHandler<Menu>(x => x.OnMenuClick);
+            MenuItem.SubmenuOpenedEvent.AddClassHandler<Menu>(x => x.OnSubmenuOpened);
+        }
+
+        /// <summary>
+        /// Gets a value indicating whether the menu is open.
+        /// </summary>
+        public bool IsOpen
+        {
+            get { return this.GetValue(IsOpenProperty); }
+            private set { this.SetValue(IsOpenProperty, value); }
+        }
+
+        /// <summary>
+        /// Gets the selected <see cref="MenuItem"/> container.
+        /// </summary>
+        private MenuItem SelectedMenuItem
+        {
+            get
+            {
+                return (this.SelectedItem != null) ?
+                    (MenuItem)this.ItemContainerGenerator.GetContainerForItem(this.SelectedItem) :
+                    null;
+            }
+        }
+
+        /// <summary>
+        /// Closes the menu.
+        /// </summary>
+        public void Close()
+        {
+            foreach (MenuItem i in this.GetLogicalChildren())
+            {
+                i.IsSubMenuOpen = false;
+            }
+
+            this.IsOpen = false;
+            this.SelectedIndex = -1;
+        }
+
+        /// <summary>
+        /// Opens the menu in response to the Alt/F10 key.
+        /// </summary>
+        public void Open()
+        {
+            this.SelectedIndex = 0;
+            this.SelectedMenuItem.Focus();
+            this.IsOpen = true;
+        }
+
+        /// <summary>
+        /// Called when the <see cref="MenuItem"/> is attached to the visual tree.
+        /// </summary>
+        /// <param name="root">The root of the visual tree.</param>
+        protected override void OnAttachedToVisualTree(IRenderRoot root)
+        {
+            base.OnAttachedToVisualTree(root);
+
+            var topLevel = root as TopLevel;
+
+            topLevel.Deactivated += this.Deactivated;
+
+            var pointerPress = topLevel.AddHandler(
+                InputElement.PointerPressedEvent,
+                this.TopLevelPreviewPointerPress,
+                RoutingStrategies.Tunnel);
+
+            this.subscription = new CompositeDisposable(
+                pointerPress,
+                Disposable.Create(() => topLevel.Deactivated -= this.Deactivated));
+
+            var inputRoot = root as IInputRoot;
+
+            if (inputRoot != null && inputRoot.AccessKeyHandler != null)
+            {
+                inputRoot.AccessKeyHandler.MainMenu = this;
+            }
+        }
+
+        /// <summary>
+        /// Called when the <see cref="Menu"/> is detached from the visual tree.
+        /// </summary>
+        /// <param name="oldRoot">The root of the visual tree being detached from.</param>
+        protected override void OnDetachedFromVisualTree(IRenderRoot oldRoot)
+        {
+            base.OnDetachedFromVisualTree(oldRoot);
+            this.subscription.Dispose();
+        }
+
+        /// <summary>
+        /// Called when a key is pressed within the menu.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        protected override void OnKeyDown(KeyEventArgs e)
+        {
+            bool menuWasOpen = this.SelectedMenuItem?.IsSubMenuOpen ?? false;
+
+            base.OnKeyDown(e);
+
+            if (menuWasOpen)
+            {
+                // If a menu item was open and we navigate to a new one with the arrow keys, open
+                // that menu and select the first item.
+                var selection = this.SelectedMenuItem;
+
+                if (selection != null && !selection.IsSubMenuOpen)
+                {
+                    selection.IsSubMenuOpen = true;
+                    selection.SelectedIndex = 0;
+                }
+            }
+        }
+
+        /// <summary>
+        /// Called when the menu loses focus.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        protected override void OnLostFocus(RoutedEventArgs e)
+        {
+            base.OnLostFocus(e);
+            this.SelectedItem = null;
+        }
+
+        /// <summary>
+        /// Called when a submenu opens somewhere in the menu.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        protected virtual void OnSubmenuOpened(RoutedEventArgs e)
+        {
+            var menuItem = e.Source as MenuItem;
+
+            if (menuItem != null && menuItem.Parent == this)
+            {
+                foreach (var child in this.GetLogicalChildren().OfType<MenuItem>())
+                {
+                    if (child != menuItem && child.IsSubMenuOpen)
+                    {
+                        child.IsSubMenuOpen = false;
+                    }
+                }
+            }
+
+            this.IsOpen = true;
+        }
+
+        /// <summary>
+        /// Called when the top-level window is deactivated.
+        /// </summary>
+        /// <param name="sender">The sender.</param>
+        /// <param name="e">The event args.</param>
+        private void Deactivated(object sender, EventArgs e)
+        {
+            this.Close();
+        }
+
+        /// <summary>
+        /// Called when a submenu is clicked somewhere in the menu.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        private void OnMenuClick(RoutedEventArgs e)
+        {
+            this.Close();
+            FocusManager.Instance.Focus(null);
+            e.Handled = true;
+        }
+
+        /// <summary>
+        /// Called when the pointer is pressed anywhere on the window.
+        /// </summary>
+        /// <param name="sender">The sender.</param>
+        /// <param name="e">The event args.</param>
+        private void TopLevelPreviewPointerPress(object sender, PointerPressEventArgs e)
+        {
+            if (this.IsOpen)
+            {
+                var control = e.Source as ILogical;
+
+                if (!this.IsLogicalParentOf(control))
+                {
+                    this.Close();
+                }
+            }
+        }
+    }
+}

Perspex.Controls/MenuItem.cs

@@ -0,0 +1,547 @@
+// -----------------------------------------------------------------------
+// <copyright file="MenuItem.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Controls
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using System.Windows.Input;
+    using Perspex.Controls.Primitives;
+    using Perspex.Input;
+    using Perspex.Interactivity;
+    using Perspex.Controls.Templates;
+    using Perspex.Controls.Presenters;
+    using Perspex.VisualTree;
+    using Perspex.Threading;
+    using Splat;
+
+    /// <summary>
+    /// A menu item control.
+    /// </summary>
+    public class MenuItem : SelectingItemsControl, ISelectable
+    {
+        /// <summary>
+        /// Defines the <see cref="Command"/> property.
+        /// </summary>
+        public static readonly PerspexProperty<ICommand> CommandProperty =
+            Button.CommandProperty.AddOwner<MenuItem>();
+
+        /// <summary>
+        /// Defines the <see cref="CommandParameter"/> property.
+        /// </summary>
+        public static readonly PerspexProperty<object> CommandParameterProperty =
+            Button.CommandParameterProperty.AddOwner<MenuItem>();
+
+        /// <summary>
+        /// Defines the <see cref="Header"/> property.
+        /// </summary>
+        public static readonly PerspexProperty<object> HeaderProperty =
+            HeaderedItemsControl.HeaderProperty.AddOwner<MenuItem>();
+
+        /// <summary>
+        /// Defines the <see cref="Icon"/> property.
+        /// </summary>
+        public static readonly PerspexProperty<object> IconProperty =
+            PerspexProperty.Register<MenuItem, object>(nameof(Icon));
+
+        /// <summary>
+        /// Defines the <see cref="IsSelected"/> property.
+        /// </summary>
+        public static readonly PerspexProperty<bool> IsSelectedProperty =
+            ListBoxItem.IsSelectedProperty.AddOwner<MenuItem>();
+
+        /// <summary>
+        /// Defines the <see cref="IsSubMenuOpen"/> property.
+        /// </summary>
+        public static readonly PerspexProperty<bool> IsSubMenuOpenProperty =
+            PerspexProperty.Register<MenuItem, bool>(nameof(IsSubMenuOpen));
+
+        /// <summary>
+        /// Defines the <see cref="Click"/> event.
+        /// </summary>
+        public static readonly RoutedEvent<RoutedEventArgs> ClickEvent =
+            RoutedEvent.Register<MenuItem, RoutedEventArgs>(nameof(Click), RoutingStrategies.Bubble);
+
+        /// <summary>
+        /// Defines the <see cref="SubmenuOpened"/> event.
+        /// </summary>
+        public static readonly RoutedEvent<RoutedEventArgs> SubmenuOpenedEvent =
+            RoutedEvent.Register<MenuItem, RoutedEventArgs>(nameof(SubmenuOpened), RoutingStrategies.Bubble);
+
+        /// <summary>
+        /// The timer used to display submenus.
+        /// </summary>
+        private IDisposable submenuTimer;
+
+        /// <summary>
+        /// The submenu popup.
+        /// </summary>
+        private Popup popup;
+
+        /// <summary>
+        /// Initializes static members of the <see cref="MenuItem"/> class.
+        /// </summary>
+        static MenuItem()
+        {
+            FocusableProperty.OverrideDefaultValue<MenuItem>(true);
+            ClickEvent.AddClassHandler<MenuItem>(x => x.OnClick);
+            SubmenuOpenedEvent.AddClassHandler<MenuItem>(x => x.OnSubmenuOpened);
+            IsSubMenuOpenProperty.Changed.AddClassHandler<MenuItem>(x => x.SubMenuOpenChanged);
+            AccessKeyHandler.AccessKeyPressedEvent.AddClassHandler<MenuItem>(x => x.AccessKeyPressed);
+        }
+
+        /// <summary>
+        /// Occurs when a <see cref="MenuItem"/> without a submenu is clicked.
+        /// </summary>
+        public event EventHandler<RoutedEventArgs> Click
+        {
+            add { this.AddHandler(ClickEvent, value); }
+            remove { this.RemoveHandler(ClickEvent, value); }
+        }
+
+        /// <summary>
+        /// Occurs when a <see cref="MenuItem"/>'s submenu is opened.
+        /// </summary>
+        public event EventHandler<RoutedEventArgs> SubmenuOpened
+        {
+            add { this.AddHandler(SubmenuOpenedEvent, value); }
+            remove { this.RemoveHandler(SubmenuOpenedEvent, value); }
+        }
+
+        /// <summary>
+        /// Gets or sets the command associated with the menu item.
+        /// </summary>
+        public ICommand Command
+        {
+            get { return this.GetValue(CommandProperty); }
+            set { this.SetValue(CommandProperty, value); }
+        }
+
+        /// <summary>
+        /// Gets or sets the parameter to pass to the <see cref="Command"/> property of a
+        /// <see cref="MenuItem"/>.
+        /// </summary>
+        public object CommandParameter
+        {
+            get { return this.GetValue(CommandParameterProperty); }
+            set { this.SetValue(CommandParameterProperty, value); }
+        }
+
+        /// <summary>
+        /// Gets or sets the <see cref="MenuItem"/>'s header.
+        /// </summary>
+        public object Header
+        {
+            get { return this.GetValue(HeaderProperty); }
+            set { this.SetValue(HeaderProperty, value); }
+        }
+
+        /// <summary>
+        /// Gets or sets the icon that appears in a <see cref="MenuItem"/>.
+        /// </summary>
+        public object Icon
+        {
+            get { return this.GetValue(IconProperty); }
+            set { this.SetValue(IconProperty, value); }
+        }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether the <see cref="MenuItem"/> is currently selected.
+        /// </summary>
+        public bool IsSelected
+        {
+            get { return this.GetValue(IsSelectedProperty); }
+            set { this.SetValue(IsSelectedProperty, value); }
+        }
+
+        /// <summary>
+        /// Gets or sets a value that indicates whether the submenu of the <see cref="MenuItem"/> is
+        /// open.
+        /// </summary>
+        public bool IsSubMenuOpen
+        {
+            get { return this.GetValue(IsSubMenuOpenProperty); }
+            set { this.SetValue(IsSubMenuOpenProperty, value); }
+        }
+
+        /// <summary>
+        /// Gets or sets a value that indicates whether the <see cref="MenuItem"/> has a submenu.
+        /// </summary>
+        public bool HasSubMenu
+        {
+            get { return !this.Classes.Contains(":empty"); }
+        }
+
+        /// <summary>
+        /// Gets a value that indicates whether the <see cref="MenuItem"/> is a top-level menu item.
+        /// </summary>
+        public bool IsTopLevel
+        {
+            get { return this.Parent is Menu; }
+        }
+
+        /// <summary>
+        /// Called when the <see cref="MenuItem"/> is clicked.
+        /// </summary>
+        /// <param name="e">The click event args.</param>
+        protected virtual void OnClick(RoutedEventArgs e)
+        {
+            if (this.Command != null)
+            {
+                this.Command.Execute(this.CommandParameter);
+            }
+        }
+
+        /// <summary>
+        /// Called when the <see cref="MenuItem"/> recieves focus.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        protected override void OnGotFocus(GotFocusEventArgs e)
+        {
+            base.OnGotFocus(e);
+            this.IsSelected = true;
+        }
+
+        /// <summary>
+        /// Called when a key is pressed in the <see cref="MenuItem"/>.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        protected override void OnKeyDown(KeyEventArgs e)
+        {
+            // Some keypresses we want to pass straight to the parent MenuItem/Menu without giving
+            // this MenuItem the chance to handle them. This is usually e.g. when the submenu is
+            // closed so passing them to the base would try to move the selection in a hidden
+            // submenu.
+            var passStraightToParent = true;
+
+            switch (e.Key)
+            {
+                case Key.Up:
+                    passStraightToParent = !this.IsSubMenuOpen;
+                    break;
+
+                case Key.Down:
+                    if (this.IsTopLevel && this.HasSubMenu && !this.IsSubMenuOpen)
+                    {
+                        this.SelectedIndex = 0;
+                        this.IsSubMenuOpen = true;
+                        e.Handled = true;
+                    }
+
+                    passStraightToParent = !this.IsSubMenuOpen;
+                    break;
+
+                case Key.Left:
+                    if (!this.IsTopLevel && this.IsSubMenuOpen)
+                    {
+                        this.IsSubMenuOpen = false;
+                        e.Handled = true;
+                    }
+
+                    passStraightToParent = this.IsTopLevel || !this.IsSubMenuOpen;
+                    break;
+
+                case Key.Right:
+                    if (!this.IsTopLevel && this.HasSubMenu && !this.IsSubMenuOpen)
+                    {
+                        this.SelectedIndex = 0;
+                        this.IsSubMenuOpen = true;
+                        e.Handled = true;
+                    }
+
+                    passStraightToParent = this.IsTopLevel || !this.IsSubMenuOpen;
+                    break;
+
+                case Key.Enter:
+                    if (this.HasSubMenu)
+                    {
+                        goto case Key.Right;
+                    }
+                    else
+                    {
+                        this.RaiseEvent(new RoutedEventArgs(ClickEvent));
+                        e.Handled = true;
+                    }
+
+                    break;
+
+                case Key.Escape:
+                    if (this.IsSubMenuOpen)
+                    {
+                        this.IsSubMenuOpen = false;
+                        e.Handled = true;
+                    }
+
+                    break;
+            }
+
+            if (!passStraightToParent)
+            {
+                base.OnKeyDown(e);
+            }
+        }
+
+        /// <summary>
+        /// Called when the pointer enters the <see cref="MenuItem"/>.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        protected override void OnPointerEnter(PointerEventArgs e)
+        {
+            base.OnPointerEnter(e);
+
+            var menu = this.Parent as Menu;
+
+            if (menu != null)
+            {
+                if (menu.IsOpen)
+                {
+                    this.IsSubMenuOpen = true;
+                }
+            }
+            else if (this.HasSubMenu && !this.IsSubMenuOpen)
+            {
+                this.submenuTimer = DispatcherTimer.Run(
+                    () => this.IsSubMenuOpen = true,
+                    TimeSpan.FromMilliseconds(400));
+            }
+        }
+
+        /// <summary>
+        /// Called when the pointer leaves the <see cref="MenuItem"/>.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        protected override void OnPointerLeave(PointerEventArgs e)
+        {
+            base.OnPointerLeave(e);
+
+            if (this.submenuTimer != null)
+            {
+                this.submenuTimer.Dispose();
+                this.submenuTimer = null;
+            }
+        }
+
+        /// <summary>
+        /// Called when the pointer is pressed over the <see cref="MenuItem"/>.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        protected override void OnPointerPressed(PointerPressEventArgs e)
+        {
+            base.OnPointerPressed(e);
+
+            if (!this.HasSubMenu)
+            {
+                this.RaiseEvent(new RoutedEventArgs(ClickEvent));
+            }
+            else if (this.IsTopLevel)
+            {
+                this.IsSubMenuOpen = !this.IsSubMenuOpen;
+            }
+            else
+            {
+                this.IsSubMenuOpen = true;
+            }
+
+            e.Handled = true;
+        }
+
+        /// <summary>
+        /// Called when a submenu is opened on this MenuItem or a child MenuItem.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        protected virtual void OnSubmenuOpened(RoutedEventArgs e)
+        {
+            var menuItem = e.Source as MenuItem;
+
+            if (menuItem != null && menuItem.Parent == this)
+            {
+                foreach (var child in this.Items.OfType<MenuItem>())
+                {
+                    if (child != menuItem && child.IsSubMenuOpen)
+                    {
+                        child.IsSubMenuOpen = false;
+                    }
+                }
+            }
+        }
+
+        /// <summary>
+        /// Called when the MenuItem's template has been applied.
+        /// </summary>
+        protected override void OnTemplateApplied()
+        {
+            base.OnTemplateApplied();
+
+            this.popup = this.GetTemplateChild<Popup>("popup");
+            this.popup.DependencyResolver = DependencyResolver.Instance;
+            this.popup.PopupRootCreated += this.PopupRootCreated;
+            this.popup.Opened += this.PopupOpened;
+            this.popup.Closed += this.PopupClosed;
+        }
+
+        /// <summary>
+        /// Called when the menu item's access key is pressed.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        private void AccessKeyPressed(RoutedEventArgs e)
+        {
+            if (this.HasSubMenu)
+            {
+                this.SelectedIndex = 0;
+                this.IsSubMenuOpen = true;
+            }
+            else
+            {
+                this.RaiseEvent(new RoutedEventArgs(ClickEvent));
+            }
+
+            e.Handled = true;
+        }
+
+        /// <summary>
+        /// Closes all submenus of the menu item.
+        /// </summary>
+        private void CloseSubmenus()
+        {
+            foreach (var child in this.Items.OfType<MenuItem>())
+            {
+                child.IsSubMenuOpen = false;
+            }
+        }
+
+        /// <summary>
+        /// Called when the <see cref="IsSubMenuOpen"/> property changes.
+        /// </summary>
+        /// <param name="e">The property change event.</param>
+        private void SubMenuOpenChanged(PerspexPropertyChangedEventArgs e)
+        {
+            var value = (bool)e.NewValue;
+
+            if (value)
+            {
+                this.RaiseEvent(new RoutedEventArgs(SubmenuOpenedEvent));
+                this.IsSelected = true;
+            }
+            else
+            {
+                this.CloseSubmenus();
+                this.SelectedIndex = -1;
+            }
+        }
+
+        /// <summary>
+        /// Called when the submenu's <see cref="PopupRoot"/> is created.
+        /// </summary>
+        /// <param name="sender">The event sender.</param>
+        /// <param name="e">The event args.</param>
+        private void PopupRootCreated(object sender, EventArgs e)
+        {
+            var popup = (Popup)sender;
+            ItemsPresenter presenter = null;
+
+            // Our ItemsPresenter is in a Popup which means that it's only created when the
+            // Popup is opened, therefore it wasn't found by ItemsControl.OnTemplateApplied.
+            // Now the Popup has been opened for the first time it should exist, so make sure
+            // the PopupRoot's template is applied and look for the ItemsPresenter.
+            foreach (var c in popup.PopupRoot.GetSelfAndVisualDescendents().OfType<Control>())
+            {
+                if (c.Name == "itemsPresenter" && c is ItemsPresenter)
+                {
+                    presenter = c as ItemsPresenter;
+                    break;
+                }
+
+                c.ApplyTemplate();
+            }
+
+            if (presenter != null)
+            {
+                // The presenter was found. Set its TemplatedParent so it thinks that it had a
+                // normal birth; may it never know its own perveristy.
+                presenter.TemplatedParent = this;
+                this.Presenter = presenter;
+            }
+        }
+
+        /// <summary>
+        /// Called when the submenu's <see cref="Popup"/> is opened.
+        /// </summary>
+        /// <param name="sender">The event sender.</param>
+        /// <param name="e">The event args.</param>
+        private void PopupOpened(object sender, EventArgs e)
+        {
+            var selected = this.SelectedItem;
+
+            if (selected != null)
+            {
+                var container = this.ItemContainerGenerator.GetContainerForItem(selected);
+
+                if (container != null)
+                {
+                    container.Focus();
+                }
+            }
+        }
+
+        /// <summary>
+        /// Called when the submenu's <see cref="Popup"/> is closed.
+        /// </summary>
+        /// <param name="sender">The event sender.</param>
+        /// <param name="e">The event args.</param>
+        private void PopupClosed(object sender, EventArgs e)
+        {
+            this.SelectedItem = null;
+        }
+
+        /// <summary>
+        /// A dependency resolver which returns a <see cref="MenuItemAccessKeyHandler"/>.
+        /// </summary>
+        private class DependencyResolver : IDependencyResolver
+        {
+            /// <summary>
+            /// Gets the default instance of <see cref="DependencyResolver"/>.
+            /// </summary>
+            public static readonly DependencyResolver Instance = new DependencyResolver();
+
+            /// <summary>
+            /// Disposes of all managed resources.
+            /// </summary>
+            public void Dispose()
+            {
+            }
+
+            /// <summary>
+            /// Gets a service of the specified type.
+            /// </summary>
+            /// <param name="serviceType">The service type.</param>
+            /// <param name="contract">An optional contract.</param>
+            /// <returns>A service of the requested type.</returns>
+            public object GetService(Type serviceType, string contract = null)
+            {
+                if (serviceType == typeof(IAccessKeyHandler))
+                {
+                    return new MenuItemAccessKeyHandler();
+                }
+                else
+                {
+                    return Locator.Current.GetService(serviceType, contract);
+                }
+            }
+
+            /// <summary>
+            /// Gets collection of services of the specified type.
+            /// </summary>
+            /// <param name="serviceType">The service type.</param>
+            /// <param name="contract">An optional contract.</param>
+            /// <returns>A collection of services of the requested type.</returns>
+            public IEnumerable<object> GetServices(Type serviceType, string contract = null)
+            {
+                return Locator.Current.GetServices(serviceType, contract);
+            }
+        }
+    }
+}

Perspex.Controls/MenuItemAccessKeyHandler.cs

@@ -0,0 +1,111 @@
+// -----------------------------------------------------------------------
+// <copyright file="MenuItemAccessKeyHandler.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Controls
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using Perspex.Input;
+    using Perspex.Interactivity;
+
+    /// <summary>
+    /// Handles access keys within a <see cref="MenuItem"/>
+    /// </summary>
+    public class MenuItemAccessKeyHandler : IAccessKeyHandler
+    {
+        /// <summary>
+        /// The registered access keys.
+        /// </summary>
+        private List<Tuple<string, IInputElement>> registered = new List<Tuple<string, IInputElement>>();
+
+        /// <summary>
+        /// The window to which the handler belongs.
+        /// </summary>
+        private IInputRoot owner;
+
+        /// <summary>
+        /// Gets or sets the window's main menu.
+        /// </summary>
+        /// <remarks>
+        /// This property is ignored as a menu item cannot have a main menu.
+        /// </remarks>
+        public IMainMenu MainMenu { get; set; }
+
+        /// <summary>
+        /// Sets the owner of the access key handler.
+        /// </summary>
+        /// <param name="owner">The owner.</param>
+        /// <remarks>
+        /// This method can only be called once, typically by the owner itself on creation.
+        /// </remarks>
+        public void SetOwner(IInputRoot owner)
+        {
+            Contract.Requires<ArgumentNullException>(owner != null);
+
+            if (this.owner != null)
+            {
+                throw new InvalidOperationException("AccessKeyHandler owner has already been set.");
+            }
+
+            this.owner = owner;
+
+            this.owner.AddHandler(InputElement.KeyDownEvent, this.OnKeyDown);
+        }
+
+        /// <summary>
+        /// Registers an input element to be associated with an access key.
+        /// </summary>
+        /// <param name="accessKey">The access key.</param>
+        /// <param name="element">The input element.</param>
+        public void Register(char accessKey, IInputElement element)
+        {
+            var existing = this.registered.FirstOrDefault(x => x.Item2 == element);
+
+            if (existing != null)
+            {
+                this.registered.Remove(existing);
+            }
+
+            this.registered.Add(Tuple.Create(accessKey.ToString().ToUpper(), element));
+        }
+
+        /// <summary>
+        /// Unregisters the access keys associated with the input element.
+        /// </summary>
+        /// <param name="element">The input element.</param>
+        public void Unregister(IInputElement element)
+        {
+            foreach (var i in this.registered.Where(x => x.Item2 == element).ToList())
+            {
+                this.registered.Remove(i);
+            }
+        }
+
+        /// <summary>
+        /// Handles a key being pressed in the menu.
+        /// </summary>
+        /// <param name="sender">The event sender.</param>
+        /// <param name="e">The event args.</param>
+        protected virtual void OnKeyDown(object sender, KeyEventArgs e)
+        {
+            if (!string.IsNullOrWhiteSpace(e.Text))
+            {
+                var text = e.Text.ToUpper();
+                var focus = this.registered
+                    .Where(x => x.Item1 == text && x.Item2.IsEffectivelyVisible)
+                    .FirstOrDefault()?.Item2;
+
+                if (focus != null)
+                {
+                    focus.RaiseEvent(new RoutedEventArgs(AccessKeyHandler.AccessKeyPressedEvent));
+                }
+
+                e.Handled = true;
+            }
+        }
+    }
+}

Perspex.Controls/Panel.cs

@@ -72,8 +72,16 @@ namespace Perspex.Controls
 
         ILogical IItemsPanel.ChildLogicalParent
         {
-            get { return this.childLogicalParent; }
+            get
-            set { this.childLogicalParent = value; }
+            {
+                return this.childLogicalParent;
+            }
+
+            set
+            {
+                this.childLogicalParent = value;
+                this.SetLogicalParent(this.Children);
+            }
         }
 
         protected virtual void OnChildrenAdded(IEnumerable<Control> child)

Perspex.Controls/Parsers/GridLengthsParser.cs

@@ -0,0 +1,53 @@
+// -----------------------------------------------------------------------
+// <copyright file="GridLengthsParser.cs" company="Steven Kirk">
+// Copyright 2014 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Controls.Parsers
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+
+
+    /// <summary>
+    /// Parses a string of <see cref="GridLength"/>s for <see cref="ColumnDefinitions"/> and
+    /// <see cref="RowDefinitions"/>.
+    /// </summary>
+    public static class GridLengthsParser
+    {
+        /// <summary>
+        /// Parses a string of <see cref="GridLength"/>s.
+        /// </summary>
+        /// <param name="s">The string.</param>
+        /// <returns>A collection of <see cref="GridLength"/>s.</returns>
+        public static IEnumerable<GridLength> Parse(string s)
+        {
+            var parts = s.Split(',').Select(x => x.ToUpperInvariant().Trim());
+
+            foreach (var part in parts)
+            {
+                if (part == "AUTO")
+                {
+                    yield return GridLength.Auto;
+                }
+                else if (part.EndsWith("*"))
+                {
+                    var valueString = part.Substring(0, part.Length - 1).Trim();
+                    var value = valueString.Length > 0 ? double.Parse(valueString) : 1;
+                    yield return new GridLength(value, GridUnitType.Star);
+                }
+                else if (part.EndsWith("PX"))
+                {
+                    var value = double.Parse(part.Substring(0, part.Length - 2));
+                    yield return new GridLength(value, GridUnitType.Pixel);
+                }
+                else
+                {
+                    throw new FormatException("Invalid grid length: " + part);
+                }
+            }
+        }
+    }
+}

Perspex.Controls/Perspex.Controls.csproj

@@ -15,6 +15,8 @@
     <ProjectTypeGuids>{786C830F-07A1-408B-BD7F-6EE04809D6DB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
     <TargetFrameworkProfile>Profile7</TargetFrameworkProfile>
     <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
+    <NuGetPackageImportStamp>
+    </NuGetPackageImportStamp>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DebugSymbols>true</DebugSymbols>
@@ -34,17 +36,29 @@
     <WarningLevel>4</WarningLevel>
   </PropertyGroup>
   <ItemGroup>
+    <Compile Include="MenuItemAccessKeyHandler.cs" />
+    <Compile Include="Parsers\GridLengthsParser.cs" />
+    <Compile Include="Primitives\AccessText.cs" />
     <Compile Include="Border.cs" />
+    <Compile Include="GlobalSuppressions.cs" />
+    <Compile Include="MenuItem.cs" />
+    <Compile Include="Menu.cs" />
     <Compile Include="Button.cs" />
     <Compile Include="AdornerTemplate.cs" />
     <Compile Include="DropDown.cs" />
     <Compile Include="IContentControl.cs" />
     <Compile Include="IItemsPanel.cs" />
+    <Compile Include="INamed.cs" />
+    <Compile Include="INavigablePanel.cs" />
+    <Compile Include="Deck.cs" />
     <Compile Include="Platform\IPopupImpl.cs" />
     <Compile Include="Platform\ITopLevelImpl.cs" />
+    <Compile Include="PlacementMode.cs" />
     <Compile Include="Popup.cs" />
     <Compile Include="IDataTemplate.cs" />
+    <Compile Include="Presenters\IItemsPresenter.cs" />
     <Compile Include="Presenters\IPresenter.cs" />
+    <Compile Include="Presenters\DeckPresenter.cs" />
     <Compile Include="Primitives\AdornerDecorator.cs" />
     <Compile Include="Primitives\AdornerLayer.cs" />
     <Compile Include="RadioButton.cs" />
@@ -88,9 +102,11 @@
     <Compile Include="Primitives\Thumb.cs" />
     <Compile Include="RequestBringIntoViewEventArgs.cs" />
     <Compile Include="Shapes\Ellipse.cs" />
+    <Compile Include="ToolTip.cs" />
     <Compile Include="UserControl.cs" />
     <Compile Include="Templates\TemplateExtensions.cs" />
     <Compile Include="TextWrapping.cs" />
+    <Compile Include="Utils\IEnumerableUtils.cs" />
     <Compile Include="Utils\StringUtils.cs" />
     <Compile Include="TopLevel.cs" />
     <Compile Include="PopupRoot.cs" />
@@ -118,8 +134,13 @@
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>
   <ItemGroup>
-    <Reference Include="Splat">
+    <Reference Include="Serilog, Version=1.5.0.0, Culture=neutral, PublicKeyToken=24c2f752a8e58a10, processorArchitecture=MSIL">
-      <HintPath>..\packages\Splat.1.6.1\lib\Portable-net45+win+wpa81+wp80\Splat.dll</HintPath>
+      <HintPath>..\packages\Serilog.1.5.5\lib\portable-net45+win+wpa81+wp80+MonoAndroid10+MonoTouch10\Serilog.dll</HintPath>
+      <Private>True</Private>
+    </Reference>
+    <Reference Include="Splat, Version=1.6.2.0, Culture=neutral, processorArchitecture=MSIL">
+      <HintPath>..\packages\Splat.1.6.2\lib\Portable-net45+win+wpa81+wp80\Splat.dll</HintPath>
+      <Private>True</Private>
     </Reference>
     <Reference Include="System.Reactive.Core">
       <HintPath>..\packages\Rx-Core.2.2.5\lib\portable-windows8+net45+wp8\System.Reactive.Core.dll</HintPath>
@@ -168,14 +189,10 @@
       <Name>Perspex.Styling</Name>
     </ProjectReference>
   </ItemGroup>
+  <ItemGroup>
+    <Analyzer Include="..\packages\StyleCop.Analyzers.1.0.0-alpha008\tools\analyzers\C#\StyleCop.Analyzers.dll" />
+  </ItemGroup>
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\Portable\$(TargetFrameworkVersion)\Microsoft.Portable.CSharp.targets" />
-  <Import Project="..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets" Condition="Exists('..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets')" />
-  <Target Name="EnsureNuGetPackageBuildImports" BeforeTargets="PrepareForBuild">
-    <PropertyGroup>
-      <ErrorText>This project references NuGet package(s) that are missing on this computer. Enable NuGet Package Restore to download them.  For more information, see http://go.microsoft.com/fwlink/?LinkID=322105. The missing file is {0}.</ErrorText>
-    </PropertyGroup>
-    <Error Condition="!Exists('..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets')" Text="$([System.String]::Format('$(ErrorText)', '..\packages\StyleCop.MSBuild.4.7.49.0\build\StyleCop.MSBuild.Targets'))" />
-  </Target>
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
        Other similar extension points exist, see Microsoft.Common.targets.
   <Target Name="BeforeBuild">

Perspex.Controls/PlacementMode.cs

@@ -0,0 +1,14 @@
+// -----------------------------------------------------------------------
+// <copyright file="PlacementMode.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Controls
+{
+    public enum PlacementMode
+    {
+        Bottom,
+        Right,
+    }
+}

Perspex.Controls/Popup.cs

@@ -8,76 +8,182 @@ namespace Perspex.Controls
 {
     using System;
     using Perspex.Interactivity;
-    using Perspex.Platform;
+    using Perspex.Collections;
     using Perspex.Rendering;
+    using Perspex.VisualTree;
+    using Splat;
 
-    public class Popup : Control
+    /// <summary>
+    /// Displays a popup window.
+    /// </summary>
+    public class Popup : Control, ILogical, IVisualTreeHost
     {
+        /// <summary>
+        /// Defines the <see cref="Child"/> property.
+        /// </summary>
         public static readonly PerspexProperty<Control> ChildProperty =
-            PerspexProperty.Register<Popup, Control>("Child");
+            PerspexProperty.Register<Popup, Control>(nameof(Child));
 
+        /// <summary>
+        /// Defines the <see cref="IsOpen"/> property.
+        /// </summary>
         public static readonly PerspexProperty<bool> IsOpenProperty =
-            PerspexProperty.Register<Popup, bool>("IsOpen");
+            PerspexProperty.Register<Popup, bool>(nameof(IsOpen));
 
+        /// <summary>
+        /// Defines the <see cref="PlacementMode"/> property.
+        /// </summary>
+        public static readonly PerspexProperty<PlacementMode> PlacementModeProperty =
+            PerspexProperty.Register<Popup, PlacementMode>(nameof(PlacementMode), defaultValue: PlacementMode.Bottom);
+
+        /// <summary>
+        /// Defines the <see cref="PlacementTarget"/> property.
+        /// </summary>
         public static readonly PerspexProperty<Control> PlacementTargetProperty =
-            PerspexProperty.Register<Popup, Control>("PlacementTarget");
+            PerspexProperty.Register<Popup, Control>(nameof(PlacementTarget));
 
+        /// <summary>
+        /// Defines the <see cref="StaysOpen"/> property.
+        /// </summary>
         public static readonly PerspexProperty<bool> StaysOpenProperty =
-            PerspexProperty.Register<Popup, bool>("StaysOpen", true);
+            PerspexProperty.Register<Popup, bool>(nameof(StaysOpen), true);
 
+        /// <summary>
+        /// The root of the popup.
+        /// </summary>
         private PopupRoot popupRoot;
 
+        /// <summary>
+        /// The top level control of the Popup's visual tree.
+        /// </summary>
         private TopLevel topLevel;
 
+        /// <summary>
+        /// The popup's logical child.
+        /// </summary>
+        private PerspexSingleItemList<ILogical> logicalChild = new PerspexSingleItemList<ILogical>();
+
+        /// <summary>
+        /// Initializes static members of the <see cref="Popup"/> class.
+        /// </summary>
         static Popup()
         {
-            IsOpenProperty.Changed.Subscribe(x =>
+            IsOpenProperty.Changed.AddClassHandler<Popup>(x => x.IsOpenChanged);
-            {
+        }
-                Popup popup = x.Sender as Popup;
 
-                if (popup != null)
+        /// <summary>
-                {
+        /// Initializes a new instance of the <see cref="Popup"/> class.
-                    if ((bool)x.NewValue)
+        /// </summary>
-                    {
+        public Popup()
-                        popup.Open();
+        {
-                    }
+            this.GetObservableWithHistory(ChildProperty).Subscribe(this.ChildChanged);
-                    else
-                    {
-                        popup.Close();
-                    }
-                }
-            });
         }
 
+        /// <summary>
+        /// Raised when the popup closes.
+        /// </summary>
+        public event EventHandler Closed;
+
+        /// <summary>
+        /// Raised when the popup opens.
+        /// </summary>
+        public event EventHandler Opened;
+
+        /// <summary>
+        /// Raised when the popup root has been created, but before it has been shown.
+        /// </summary>
+        public event EventHandler PopupRootCreated;
+
+        /// <summary>
+        /// Gets or sets the control to display in the popup.
+        /// </summary>
         public Control Child
         {
             get { return this.GetValue(ChildProperty); }
             set { this.SetValue(ChildProperty, value); }
         }
 
+        /// <summary>
+        /// Gets or sets a dependency resolver for the <see cref="PopupRoot"/>.
+        /// </summary>
+        /// <remarks>
+        /// This property allows a client to customize the behaviour of the popup by injecting
+        /// a specialized dependency resolver into the <see cref="PopupRoot"/>'s constructor.
+        /// </remarks>
+        public IDependencyResolver DependencyResolver
+        {
+            get;
+            set;
+        }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether the popup is currently open.
+        /// </summary>
         public bool IsOpen
         {
             get { return this.GetValue(IsOpenProperty); }
             set { this.SetValue(IsOpenProperty, value); }
         }
 
+        /// <summary>
+        /// Gets or sets the placement mode of the popup in relation to the <see cref="PlacementTarget"/>.
+        /// </summary>
+        public PlacementMode PlacementMode
+        {
+            get { return this.GetValue(PlacementModeProperty); }
+            set { this.SetValue(PlacementModeProperty, value); }
+        }
+
+        /// <summary>
+        /// Gets or sets the control that is used to determine the popup's position.
+        /// </summary>
         public Control PlacementTarget
         {
             get { return this.GetValue(PlacementTargetProperty); }
             set { this.SetValue(PlacementTargetProperty, value); }
         }
 
+        /// <summary>
+        /// Gets the root of the popup window.
+        /// </summary>
+        public PopupRoot PopupRoot
+        {
+            get { return this.popupRoot; }
+        }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether the popup should stay open when the popup loses focus.
+        /// </summary>
         public bool StaysOpen
         {
             get { return this.GetValue(StaysOpenProperty); }
             set { this.SetValue(StaysOpenProperty, value); }
         }
 
+        /// <summary>
+        /// Gets the logical children of the popup.
+        /// </summary>
+        IPerspexReadOnlyList<ILogical> ILogical.LogicalChildren
+        {
+            get { return this.logicalChild; }
+        }
+
+        /// <summary>
+        /// Gets the root of the popup window.
+        /// </summary>
+        IVisual IVisualTreeHost.Root
+        {
+            get { return this.popupRoot; }
+        }
+
+        /// <summary>
+        /// Opens the popup.
+        /// </summary>
         public void Open()
         {
             if (this.popupRoot == null)
             {
-                this.popupRoot = new PopupRoot()
+                this.popupRoot = new PopupRoot(this.DependencyResolver)
                 {
                     Parent = this,
                     [~PopupRoot.ContentProperty] = this[~ChildProperty],
@@ -95,9 +201,16 @@ namespace Perspex.Controls
             this.popupRoot.AddHandler(PopupRoot.PointerPressedEvent, this.MaybeClose, RoutingStrategies.Bubble, true);
             this.topLevel.AddHandler(TopLevel.PointerPressedEvent, this.MaybeClose, RoutingStrategies.Tunnel);
 
+            this.PopupRootCreated?.Invoke(this, EventArgs.Empty);
+
             this.popupRoot.Show();
+            this.IsOpen = true;
+            this.Opened?.Invoke(this, EventArgs.Empty);
         }
 
+        /// <summary>
+        /// Closes the popup.
+        /// </summary>
         public void Close()
         {
             if (this.popupRoot != null)
@@ -109,30 +222,98 @@ namespace Perspex.Controls
             }
 
             this.IsOpen = false;
+            this.Closed?.Invoke(this, EventArgs.Empty);
         }
 
+        /// <summary>
+        /// Measures the control.
+        /// </summary>
+        /// <param name="availableSize">The available size for the control.</param>
+        /// <returns>A size of 0,0 as Popup itself takes up no space.</returns>
         protected override Size MeasureCore(Size availableSize)
         {
             return new Size();
         }
 
+        /// <summary>
+        /// Called when the control is added to the visual tree.
+        /// </summary>
+        /// <param name="root">THe root of the visual tree.</param>
         protected override void OnAttachedToVisualTree(IRenderRoot root)
         {
             base.OnAttachedToVisualTree(root);
             this.topLevel = root as TopLevel;
         }
 
-        protected override void OnDetachedFromVisualTree(IRenderRoot oldRoot)
+        /// <summary>
+        /// Called when the control is removed to the visual tree.
+        /// </summary>
+        /// <param name="root">THe root of the visual tree.</param>
+        protected override void OnDetachedFromVisualTree(IRenderRoot root)
         {
-            base.OnDetachedFromVisualTree(oldRoot);
+            base.OnDetachedFromVisualTree(root);
             this.topLevel = null;
         }
 
+        /// <summary>
+        /// Called when the <see cref="IsOpen"/> property changes.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        private void IsOpenChanged(PerspexPropertyChangedEventArgs e)
+        {
+            if ((bool)e.NewValue)
+            {
+                this.Open();
+            }
+            else
+            {
+                this.Close();
+            }
+        }
+
+        /// <summary>
+        /// Called when the <see cref="Child"/> property changes.
+        /// </summary>
+        /// <param name="values">The old and new values.</param>
+        private void ChildChanged(Tuple<Control, Control> values)
+        {
+            if (values.Item1 != null)
+            {
+                values.Item1.Parent = null;
+            }
+
+            if (values.Item2 != null)
+            {
+                values.Item2.Parent = this;
+            }
+
+            this.logicalChild.SingleItem = values.Item2;
+        }
+
+        /// <summary>
+        /// Gets the position for the popup based on the placement properties.
+        /// </summary>
+        /// <returns>The popup's position in screen coordinates.</returns>
         private Point GetPosition()
         {
-            if (this.PlacementTarget != null)
+            var target = this.PlacementTarget ?? this.GetVisualParent<Control>();            
+            Point point;
+
+            if (target != null)
             {
-                return this.PlacementTarget.PointToScreen(new Point(0, this.PlacementTarget.Bounds.Size.Height));
+                switch (this.PlacementMode)
+                {
+                    case PlacementMode.Bottom:
+                        point = new Point(0, target.Bounds.Height);
+                        break;
+                    case PlacementMode.Right:
+                        point = new Point(target.Bounds.Width, 0);
+                        break;
+                    default:
+                        throw new InvalidOperationException("Invalid value for Popup.PlacementMode");
+                }
+
+                return target.PointToScreen(point);
             }
             else
             {
@@ -140,6 +321,12 @@ namespace Perspex.Controls
             }
         }
 
+        /// <summary>
+        /// Conditionally closes the popup in response to an event, based on the value of the
+        /// <see cref="StaysOpen"/> property.
+        /// </summary>
+        /// <param name="sender">The event sender.</param>
+        /// <param name="e">The event args.</param>
         private void MaybeClose(object sender, EventArgs e)
         {
             if (!this.StaysOpen)

Perspex.Controls/PopupRoot.cs

@@ -6,41 +6,99 @@
 
 namespace Perspex.Controls
 {
+    using System;
+    using Perspex.Interactivity;
     using Perspex.Media;
     using Perspex.Platform;
     using Splat;
+    using Perspex.VisualTree;
 
-    public class PopupRoot : TopLevel
+    /// <summary>
+    /// The root window of a <see cref="Popup"/>.
+    /// </summary>
+    public class PopupRoot : TopLevel, IInteractive, IHostedVisualTreeRoot
     {
+        /// <summary>
+        /// Initializes static members of the <see cref="PopupRoot"/> class.
+        /// </summary>
         static PopupRoot()
         {
             BackgroundProperty.OverrideDefaultValue(typeof(PopupRoot), Brushes.White);
         }
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PopupRoot"/> class.
+        /// </summary>
         public PopupRoot()
-            : base(Locator.Current.GetService<IPopupImpl>())
+            : this(null)
         {
         }
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="PopupRoot"/> class.
+        /// </summary>
+        /// <param name="dependencyResolver">
+        /// The dependency resolver to use. If null the default dependency resolver will be used.
+        /// </param>
+        public PopupRoot(IDependencyResolver dependencyResolver)
+            : base(Locator.Current.GetService<IPopupImpl>(), dependencyResolver)
+        {
+            this.GetObservable(ParentProperty).Subscribe(x => this.InheritanceParent = x);
+        }
+
+        /// <summary>
+        /// Gets the platform-specific window implementation.
+        /// </summary>
         public new IPopupImpl PlatformImpl
         {
             get { return (IPopupImpl)base.PlatformImpl; }
         }
 
+        /// <summary>
+        /// Gets the parent control in the event route.
+        /// </summary>
+        /// <remarks>
+        /// Popup events are passed to their parent window. This facilitates this.
+        /// </remarks>
+        IInteractive IInteractive.InteractiveParent
+        {
+            get { return this.Parent; }
+        }
+
+        /// <summary>
+        /// Gets the control that is hosting the popup root.
+        /// </summary>
+        IVisual IHostedVisualTreeRoot.Host
+        {
+            get { return this.Parent; }
+        }
+
+        /// <summary>
+        /// Sets the position of the popup in screen coordinates.
+        /// </summary>
+        /// <param name="p">The position.</param>
         public void SetPosition(Point p)
         {
             this.PlatformImpl.SetPosition(p);
         }
 
+        /// <summary>
+        /// Hides the popup.
+        /// </summary>
         public void Hide()
         {
             this.PlatformImpl.Hide();
+            this.IsVisible = false;
         }
 
+        /// <summary>
+        /// Shows the popup.
+        /// </summary>
         public void Show()
         {
             this.PlatformImpl.Show();
-            this.ExecuteLayoutPass();
+            this.LayoutManager.ExecuteLayoutPass();
+            this.IsVisible = true;
         }
     }
 }

Perspex.Controls/Presenters/ContentPresenter.cs

@@ -65,7 +65,7 @@ namespace Perspex.Controls.Presenters
             if (child != null)
             {
                 child.Measure(availableSize);
-                return child.DesiredSize.Value;
+                return child.DesiredSize;
             }
 
             return new Size();
@@ -87,6 +87,8 @@ namespace Perspex.Controls.Presenters
             if (content != null)
             {
                 result = this.MaterializeDataTemplate(content);
+                result.Parent = this.TemplatedParent as Control;
+
                 var templatedParent = this.TemplatedParent as TemplatedControl;
 
                 if (templatedParent != null)

Perspex.Controls/Presenters/DeckPresenter.cs

@@ -0,0 +1,159 @@
+// -----------------------------------------------------------------------
+// <copyright file="DeckPresenter.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Controls.Presenters
+{
+    using Perspex.Animation;
+    using Perspex.Controls.Generators;
+    using Perspex.Controls.Primitives;
+    using Perspex.Controls.Utils;
+    using Perspex.Input;
+    using Perspex.Styling;
+    using System;
+    using System.Collections;
+    using System.Linq;
+    using System.Reactive.Linq;
+
+    public class DeckPresenter : Control, IItemsPresenter, ITemplatedControl
+    {
+        public static readonly PerspexProperty<IEnumerable> ItemsProperty =
+            ItemsControl.ItemsProperty.AddOwner<DeckPresenter>();
+
+        public static readonly PerspexProperty<ItemsPanelTemplate> ItemsPanelProperty =
+            ItemsControl.ItemsPanelProperty.AddOwner<DeckPresenter>();
+
+        public static readonly PerspexProperty<object> SelectedItemProperty =
+            SelectingItemsControl.SelectedItemProperty.AddOwner<DeckPresenter>();
+
+        public static readonly PerspexProperty<IPageTransition> TransitionProperty =
+            Deck.TransitionProperty.AddOwner<DeckPresenter>();
+
+        private bool createdPanel;
+
+        public DeckPresenter()
+        {
+            this.GetObservableWithHistory(SelectedItemProperty).Subscribe(this.SelectedItemChanged);
+        }
+
+        public ItemContainerGenerator ItemContainerGenerator
+        {
+            get;
+            private set;
+        }
+
+        public IEnumerable Items
+        {
+            get { return this.GetValue(ItemsProperty); }
+            set { this.SetValue(ItemsProperty, value); }
+        }
+
+        public ItemsPanelTemplate ItemsPanel
+        {
+            get { return this.GetValue(ItemsPanelProperty); }
+            set { this.SetValue(ItemsPanelProperty, value); }
+        }
+
+        public object SelectedItem
+        {
+            get { return this.GetValue(SelectedItemProperty); }
+            set { this.SetValue(SelectedItemProperty, value); }
+        }
+
+        public Panel Panel
+        {
+            get;
+            private set;
+        }
+
+        public IPageTransition Transition
+        {
+            get { return this.GetValue(TransitionProperty); }
+            set { this.SetValue(TransitionProperty, value); }
+        }
+
+        public override sealed void ApplyTemplate()
+        {
+            if (!this.createdPanel)
+            {
+                this.CreatePanel();
+            }
+        }
+
+        protected override Size MeasureOverride(Size availableSize)
+        {
+            this.Panel.Measure(availableSize);
+            return this.Panel.DesiredSize;
+        }
+
+        protected override Size ArrangeOverride(Size finalSize)
+        {
+            this.Panel.Arrange(new Rect(finalSize));
+            return finalSize;
+        }
+
+        private void CreatePanel()
+        {
+            this.ClearVisualChildren();
+            this.Panel = this.ItemsPanel.Build();
+            this.Panel.TemplatedParent = this;
+            ((IItemsPanel)this.Panel).ChildLogicalParent = this.TemplatedParent as ILogical;
+            this.AddVisualChild(this.Panel);
+            this.createdPanel = true;
+            this.SelectedItemChanged(Tuple.Create<object, object>(null, this.SelectedItem));
+        }
+
+        private IItemContainerGenerator GetGenerator()
+        {
+            if (this.ItemContainerGenerator == null)
+            {
+                ItemsControl i = this.TemplatedParent as ItemsControl;
+                this.ItemContainerGenerator = i?.ItemContainerGenerator ?? new ItemContainerGenerator(this);
+            }
+
+            return this.ItemContainerGenerator;
+        }
+
+        private async void SelectedItemChanged(Tuple<object, object> value)
+        {
+            if (this.createdPanel)
+            {
+                var generator = this.GetGenerator();
+                Control from = null;
+                Control to = null;
+                int fromIndex = -1;
+                int toIndex = -1;
+
+                if (value.Item1 != null)
+                {
+                    from = generator.GetContainerForItem(value.Item1);
+                    fromIndex = this.Items.IndexOf(value.Item1);
+                }
+
+                if (value.Item2 != null)
+                {
+                    to = generator.Generate(new[] { value.Item2 }).FirstOrDefault();
+
+                    if (to != null)
+                    {
+                        this.Panel.Children.Add(to);
+                        toIndex = this.Items.IndexOf(value.Item2);
+                    }
+                }
+
+                if (this.Transition != null)
+                {
+                    await this.Transition.Start(from, to, fromIndex < toIndex);
+                }
+
+                if (from != null)
+                {
+                    this.Panel.Children.Remove(from);
+                    generator.Remove(new[] { value.Item1 });
+                }
+            }
+        }
+    }
+}

Perspex.Controls/Presenters/IItemsPresenter.cs

@@ -0,0 +1,13 @@
+// -----------------------------------------------------------------------
+// <copyright file="IPresenter.cs" company="Steven Kirk">
+// Copyright 2014 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Controls.Presenters
+{
+    public interface IItemsPresenter : IPresenter
+    {
+        Panel Panel { get; }
+    }
+}

Perspex.Controls/Presenters/IPresenter.cs

@@ -18,7 +18,7 @@ namespace Perspex.Controls.Presenters
     /// of a <see cref="TemplatedControl"/> then that signals that the visual child
     /// of the presenter is not a part of the template.
     /// </remarks>
-    public interface IPresenter : IVisual
+    public interface IPresenter : IVisual, INamed
     {
     }
 }

Perspex.Controls/Presenters/ItemsPresenter.cs

@@ -6,14 +6,15 @@
 
 namespace Perspex.Controls.Presenters
 {
+    using Perspex.Controls.Generators;
+    using Perspex.Input;
+    using Perspex.Styling;
     using System;
     using System.Collections;
     using System.Collections.Specialized;
     using System.Reactive.Linq;
-    using Perspex.Controls.Generators;
-    using Perspex.Styling;
 
-    public class ItemsPresenter : Control, IVisual, IPresenter, ITemplatedControl
+    public class ItemsPresenter : Control, IItemsPresenter, ITemplatedControl
     {
         public static readonly PerspexProperty<IEnumerable> ItemsProperty =
             ItemsControl.ItemsProperty.AddOwner<ItemsPresenter>();
@@ -23,11 +24,24 @@ namespace Perspex.Controls.Presenters
 
         private bool createdPanel;
 
+        static ItemsPresenter()
+        {
+            KeyboardNavigation.TabNavigationProperty.OverrideDefaultValue(
+                typeof(ItemsPresenter),
+                KeyboardNavigationMode.Once);
+        }
+
         public ItemsPresenter()
         {
             this.GetObservableWithHistory(ItemsProperty).Subscribe(this.ItemsChanged);
         }
 
+        public ItemContainerGenerator ItemContainerGenerator
+        {
+            get;
+            private set;
+        }
+
         public IEnumerable Items
         {
             get { return this.GetValue(ItemsProperty); }
@@ -57,7 +71,7 @@ namespace Perspex.Controls.Presenters
         protected override Size MeasureOverride(Size availableSize)
         {
             this.Panel.Measure(availableSize);
-            return this.Panel.DesiredSize.Value;
+            return this.Panel.DesiredSize;
         }
 
         protected override Size ArrangeOverride(Size finalSize)
@@ -71,6 +85,7 @@ namespace Perspex.Controls.Presenters
             this.ClearVisualChildren();
             this.Panel = this.ItemsPanel.Build();
             this.Panel.TemplatedParent = this;
+            KeyboardNavigation.SetTabNavigation(this.Panel, KeyboardNavigation.GetTabNavigation(this));
             ((IItemsPanel)this.Panel).ChildLogicalParent = this.TemplatedParent as ILogical;
             this.AddVisualChild(this.Panel);
             this.createdPanel = true;
@@ -79,14 +94,13 @@ namespace Perspex.Controls.Presenters
 
         private IItemContainerGenerator GetGenerator()
         {
-            ItemsControl i = this.TemplatedParent as ItemsControl;
+            if (this.ItemContainerGenerator == null)
-
-            if (i == null)
             {
-                throw new InvalidOperationException("ItemsPresenter must be part of an ItemsControl template.");
+                ItemsControl i = this.TemplatedParent as ItemsControl;
+                this.ItemContainerGenerator = i?.ItemContainerGenerator ?? new ItemContainerGenerator(this);
             }
 
-            return i.ItemContainerGenerator;
+            return this.ItemContainerGenerator;
         }
 
         private void ItemsChanged(Tuple<IEnumerable, IEnumerable> value)

Perspex.Controls/Presenters/ScrollContentPresenter.cs

@@ -76,7 +76,7 @@ namespace Perspex.Controls.Presenters
                 }
 
                 content.Measure(measureSize);
-                var size = content.DesiredSize.Value;
+                var size = content.DesiredSize;
                 this.measuredExtent = size;
                 return size.Constrain(availableSize);
             }
@@ -95,7 +95,10 @@ namespace Perspex.Controls.Presenters
 
             if (child != null)
             {
-                child.Arrange(new Rect((Point)(-this.Offset), child.DesiredSize.Value));
+                var size = new Size(
+                    Math.Max(finalSize.Width, child.DesiredSize.Width),
+                    Math.Max(finalSize.Height, child.DesiredSize.Height));
+                child.Arrange(new Rect((Point)(-this.Offset), size));
                 return finalSize;
             }
 

Perspex.Controls/Presenters/TextPresenter.cs

@@ -100,7 +100,14 @@ namespace Perspex.Controls.Presenters
 
                 if (this.caretBlink)
                 {
-                    context.DrawLine(new Pen(caretBrush, 1), charPos.TopLeft, charPos.BottomLeft);
+                    var x = Math.Floor(charPos.X) + 0.5;
+                    var y = Math.Floor(charPos.Y) + 0.5;
+                    var b = Math.Ceiling(charPos.Bottom) - 0.5;
+
+                    context.DrawLine(
+                        new Pen(caretBrush, 1), 
+                        new Point(x, y), 
+                        new Point(x, b));
                 }
             }
         }
@@ -133,9 +140,9 @@ namespace Perspex.Controls.Presenters
             }
         }
 
-        protected override FormattedText CreateFormattedText()
+        protected override FormattedText CreateFormattedText(Size constraint)
         {
-            var result = base.CreateFormattedText();
+            var result = base.CreateFormattedText(constraint);
             var selectionStart = this.SelectionStart;
             var selectionEnd = this.SelectionEnd;
             var start = Math.Min(selectionStart, selectionEnd);
@@ -165,6 +172,7 @@ namespace Perspex.Controls.Presenters
                     this.FontFamily,
                     this.FontSize,
                     this.FontStyle,
+                    TextAlignment.Left,
                     this.FontWeight))
                 {
                     return formattedText.Measure();

Perspex.Controls/Primitives/AccessText.cs

@@ -0,0 +1,191 @@
+// -----------------------------------------------------------------------
+// <copyright file="AccessText.cs" company="Steven Kirk">
+// Copyright 2015 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Controls.Primitives
+{
+    using System;
+    using Perspex.Media;
+    using Perspex.Input;
+    using Perspex.Rendering;
+
+
+
+    /// <summary>
+    /// A text block that displays a character prefixed with an underscore as an access key.
+    /// </summary>
+    public class AccessText : TextBlock
+    {
+        /// <summary>
+        /// Defines the <see cref="ShowAccessKey"/> attached property.
+        /// </summary>
+        public static readonly PerspexProperty<bool> ShowAccessKeyProperty =
+            PerspexProperty.RegisterAttached<AccessText, Control, bool>("ShowAccessKey", inherits: true);
+
+        /// <summary>
+        /// The access key handler for the current window.
+        /// </summary>
+        private IAccessKeyHandler accessKeys;
+
+        /// <summary>
+        /// Initializes static members of the <see cref="AccessText"/> class.
+        /// </summary>
+        static AccessText()
+        {
+            AffectsRender(ShowAccessKeyProperty);
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="AccessText"/> class.
+        /// </summary>
+        public AccessText()
+        {
+            this.GetObservable(TextProperty).Subscribe(this.TextChanged);
+        }
+
+        /// <summary>
+        /// Gets the access key.
+        /// </summary>
+        public char AccessKey
+        {
+            get;
+            private set;
+        }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether the access key should be underlined.
+        /// </summary>
+        public bool ShowAccessKey
+        {
+            get { return this.GetValue(ShowAccessKeyProperty); }
+            set { this.SetValue(ShowAccessKeyProperty, value); }
+        }
+
+        /// <summary>
+        /// Renders the <see cref="AccessText"/> to a drawing context.
+        /// </summary>
+        /// <param name="context">The drawing context.</param>
+        public override void Render(IDrawingContext context)
+        {
+            base.Render(context);
+
+            int underscore = this.Text?.IndexOf('_') ?? -1;
+
+            if (underscore != -1 && this.ShowAccessKey)
+            {
+                var rect = this.FormattedText.HitTestTextPosition(underscore);
+                var offset = new Vector(0, -0.5);
+                context.DrawLine(
+                    new Pen(this.Foreground, 1),
+                    rect.BottomLeft + offset,
+                    rect.BottomRight + offset);
+            }
+        }
+
+        /// <summary>
+        /// Creates the <see cref="FormattedText"/> used to render the text.
+        /// </summary>
+        /// <param name="constraint">The constraint of the text.</param>
+        /// <returns>A <see cref="FormattedText"/> object.</returns>
+        protected override FormattedText CreateFormattedText(Size constraint)
+        {
+            var result = new FormattedText(
+                this.StripAccessKey(this.Text),
+                this.FontFamily,
+                this.FontSize,
+                this.FontStyle,
+                this.TextAlignment,
+                this.FontWeight);
+            result.Constraint = constraint;
+            return result;
+        }
+
+        /// <summary>
+        /// Measures the control.
+        /// </summary>
+        /// <param name="availableSize">The available size for the control.</param>
+        /// <returns>The desired size.</returns>
+        protected override Size MeasureOverride(Size availableSize)
+        {
+            var result = base.MeasureOverride(availableSize);
+            return result.WithHeight(result.Height + 1);
+        }
+
+        /// <summary>
+        /// Called when the control is attached to a visual tree.
+        /// </summary>
+        /// <param name="root">The root of the visual tree.</param>
+        protected override void OnAttachedToVisualTree(IRenderRoot root)
+        {
+            base.OnAttachedToVisualTree(root);
+            this.accessKeys = (root as IInputRoot)?.AccessKeyHandler;
+
+            if (this.accessKeys != null && this.AccessKey != 0)
+            {
+                this.accessKeys.Register(this.AccessKey, this);
+            }
+        }
+
+        /// <summary>
+        /// Called when the control is detached from a visual tree.
+        /// </summary>
+        /// <param name="root">The root of the visual tree.</param>
+        protected override void OnDetachedFromVisualTree(IRenderRoot root)
+        {
+            base.OnDetachedFromVisualTree(root);
+
+            if (this.accessKeys != null && this.AccessKey != 0)
+            {
+                this.accessKeys.Unregister(this);
+                this.accessKeys = null;
+            }
+        }
+
+        /// <summary>
+        /// Returns a string with the first underscore stripped.
+        /// </summary>
+        /// <param name="text">The text.</param>
+        /// <returns>The text with the first underscore stripped.</returns>
+        private string StripAccessKey(string text)
+        {
+            var position = text.IndexOf('_');
+
+            if (position == -1)
+            {
+                return text;
+            }
+            else
+            {
+                return text.Substring(0, position) + text.Substring(position + 1);
+            }
+        }
+
+        /// <summary>
+        /// Called when the <see cref="Text"/> property changes.
+        /// </summary>
+        /// <param name="text">The new text.</param>
+        private void TextChanged(string text)
+        {
+            var key = (char)0;
+
+            if (text != null)
+            {
+                int underscore = text.IndexOf('_');
+
+                if (underscore != -1 && underscore < text.Length - 1)
+                {
+                    key = text[underscore + 1];
+                }
+            }
+
+            this.AccessKey = key;
+
+            if (this.accessKeys != null && this.AccessKey != 0)
+            {
+                this.accessKeys.Register(this.AccessKey, this);
+            }
+        }
+    }
+}

Perspex.Controls/Primitives/AdornerLayer.cs

@@ -6,6 +6,7 @@
 
 namespace Perspex.Controls.Primitives
 {
+    using System;
     using System.Collections.Generic;
     using System.Linq;
     using Perspex.VisualTree;
@@ -16,8 +17,14 @@ namespace Perspex.Controls.Primitives
         public static PerspexProperty<Visual> AdornedElementProperty =
             PerspexProperty.RegisterAttached<AdornerLayer, Visual, Visual>("AdornedElement");
 
+        private static PerspexProperty<AdornedElementInfo> AdornedElementInfoProperty =
+            PerspexProperty.RegisterAttached<AdornerLayer, Visual, AdornedElementInfo>("AdornedElementInfo");
+
+        private BoundsTracker tracker = new BoundsTracker();
+
         static AdornerLayer()
         {
+            AdornedElementProperty.Changed.Subscribe(AdornedElementChanged);
             IsHitTestVisibleProperty.OverrideDefaultValue(typeof(AdornerLayer), false);
         }
 
@@ -45,25 +52,28 @@ namespace Perspex.Controls.Primitives
 
             foreach (var child in this.Children)
             {
-                var adorned = GetAdornedElement(child);
+                var info = child.GetValue(AdornedElementInfoProperty);
 
-                if (adorned != null)
+                if (info != null)
                 {
-                    var transform = adorned.TransformToVisual(parent);
+                    child.Arrange(info.Bounds.Bounds);
-                    var position = new Point(0, 0) * transform;
-                    child.Arrange(new Rect(position, adorned.Bounds.Size));
                 }
                 else
                 {
-                    child.Arrange(new Rect(child.DesiredSize.Value));
+                    child.Arrange(new Rect(child.DesiredSize));
                 }
             }
 
             return finalSize;
         }
 
-        protected override void OnChildrenAdded(IEnumerable<Control> child)
+        protected override void OnChildrenAdded(IEnumerable<Control> children)
         {
+            foreach (var i in children)
+            {
+                this.UpdateAdornedElement(i, i.GetValue(AdornedElementProperty));
+            }
+
             this.InvalidateArrange();
         }
 
@@ -71,5 +81,54 @@ namespace Perspex.Controls.Primitives
         {
             this.InvalidateArrange();
         }
+
+        private void UpdateAdornedElement(Visual adorner, Visual adorned)
+        {
+            var info = adorner.GetValue(AdornedElementInfoProperty);
+
+            if (info != null)
+            {
+                info.Subscription.Dispose();
+
+                if (adorned == null)
+                {
+                    adorner.ClearValue(AdornedElementInfoProperty);
+                }
+            }
+
+            if (adorned != null)
+            {
+                if (info == null)
+                {
+                    info = new AdornedElementInfo();
+                    adorner.SetValue(AdornedElementInfoProperty, info);
+                }
+
+                info.Subscription = this.tracker.Track(adorned).Subscribe(x =>
+                {
+                    info.Bounds = x;
+                    this.InvalidateArrange();
+                });
+            }
+        }
+
+        private static void AdornedElementChanged(PerspexPropertyChangedEventArgs e)
+        {
+            var adorner = (Visual)e.Sender;
+            var adorned = (Visual)e.NewValue;
+            var layer = adorner.GetVisualParent<AdornerLayer>();
+
+            if (layer != null)
+            {
+                layer.UpdateAdornedElement(adorner, adorned);
+            }
+        }
+
+        private class AdornedElementInfo
+        {
+            public IDisposable Subscription { get; set; }
+
+            public TransformedBounds Bounds { get; set; }
+        }
     }
 }

Perspex.Controls/Primitives/ScrollBar.cs

@@ -9,6 +9,7 @@ namespace Perspex.Controls.Primitives
     using System;
     using System.Reactive;
     using System.Reactive.Linq;
+    using Perspex.Controls.Templates;
 
     public class ScrollBar : TemplatedControl
     {
@@ -88,6 +89,18 @@ namespace Perspex.Controls.Primitives
             return base.MeasureOverride(availableSize);
         }
 
+        protected override void OnTemplateApplied()
+        {
+            base.OnTemplateApplied();
+
+            // Binding between this.Value and track.Value must be done explicitly like this rather 
+            // than using standard bindings as it shouldn't be able to to be overridden by binding
+            // e.g. ScrollBar.Value.
+            var track = this.GetTemplateChild<Track>("track");
+            track.GetObservable(ValueProperty).Subscribe(x => this.Value = x);
+            this.GetObservable(ValueProperty).Subscribe(x => track.Value = x);
+        }
+
         private bool CalculateIsVisible()
         {
             switch (this.Visibility)

Perspex.Controls/Primitives/SelectingItemsControl.cs

@@ -7,112 +7,219 @@
 namespace Perspex.Controls.Primitives
 {
     using System;
-    using System.Collections;
     using System.Linq;
+    using System.Collections;
+    using System.Collections.Specialized;
+    using Perspex.Controls.Utils;
     using Perspex.Input;
     using Perspex.VisualTree;
+    using Perspex.Interactivity;
 
-    public class SelectingItemsControl : ItemsControl
+    /// <summary>
+    /// An <see cref="ItemsControl"/> that maintains a selection.
+    /// </summary>
+    /// <remarks>
+    /// TODO: Support multiple selection.
+    /// </remarks>
+    public abstract class SelectingItemsControl : ItemsControl
     {
+        /// <summary>
+        /// Defines the <see cref="SelectedIndex"/> property.
+        /// </summary>
+        public static readonly PerspexProperty<int> SelectedIndexProperty =
+            PerspexProperty.Register<SelectingItemsControl, int>(
+                nameof(SelectedIndex),
+                defaultValue: -1,
+                coerce: CoerceSelectedIndex);
+
+        /// <summary>
+        /// Defines the <see cref="SelectedItem"/> property.
+        /// </summary>
         public static readonly PerspexProperty<object> SelectedItemProperty =
-            PerspexProperty.Register<SelectingItemsControl, object>("SelectedItem");
+            PerspexProperty.Register<SelectingItemsControl, object>(
+                nameof(SelectedItem),
+                coerce: CoerceSelectedItem);
+
+        /// <summary>
+        /// Event that should be raised by items that implement <see cref="ISelectable"/> to
+        /// notify the parent <see cref="SelectingItemsControl"/> that their selection state
+        /// has changed.
+        /// </summary>
+        public static readonly RoutedEvent<RoutedEventArgs> IsSelectedChangedEvent =
+            RoutedEvent.Register<SelectingItemsControl, RoutedEventArgs>("IsSelectedChanged", RoutingStrategies.Bubble);
 
+        /// <summary>
+        /// Initializes static members of the <see cref="SelectingItemsControl"/> class.
+        /// </summary>
         static SelectingItemsControl()
         {
-            FocusableProperty.OverrideDefaultValue(typeof(SelectingItemsControl), true);
+            IsSelectedChangedEvent.AddClassHandler<SelectingItemsControl>(x => x.ItemIsSelectedChanged);
-
+            SelectedIndexProperty.Changed.Subscribe(SelectedIndexChanged);
-            SelectedItemProperty.Changed.Subscribe(x =>
+            SelectedItemProperty.Changed.Subscribe(SelectedItemChanged);
-            {
+        }
-                var control = x.Sender as SelectingItemsControl;
 
-                if (control != null)
+        /// <summary>
-                {
+        /// Gets or sets the index of the selected item.
-                    control.SelectedItemChanged(x.NewValue);
+        /// </summary>
-                }
+        public int SelectedIndex
-            });
+        {
+            get { return this.GetValue(SelectedIndexProperty); }
+            set { this.SetValue(SelectedIndexProperty, value); }
         }
 
+        /// <summary>
+        /// Gets or sets the selected item.
+        /// </summary>
         public object SelectedItem
         {
             get { return this.GetValue(SelectedItemProperty); }
             set { this.SetValue(SelectedItemProperty, value); }
         }
 
-        protected static int GetIndexOfItem(IEnumerable items, object item)
+        /// <summary>
+        /// Called when the <see cref="Items"/> property changes.
+        /// </summary>
+        /// <param name="oldValue">The old value of the property.</param>
+        /// <param name="newValue">The new value of the property.</param>
+        protected override void ItemsChanged(IEnumerable oldValue, IEnumerable newValue)
         {
-            if (items != null)
+            base.ItemsChanged(oldValue, newValue);
-            {
+
-                int index = 0;
+            var selected = this.SelectedItem;
 
-                foreach (var i in items)
+            if (selected != null)
+            {
+                if (newValue == null || !newValue.Contains(selected))
                 {
-                    if (object.ReferenceEquals(i, item))
+                    this.SelectedItem = null;
+                }
+            }
+        }
+
+        /// <summary>
+        /// Called when a <see cref="INotifyCollectionChanged.CollectionChanged"/> event is raised
+        /// on <see cref="Items"/>.
+        /// </summary>
+        /// <param name="sender">The event sender.</param>
+        /// <param name="e">The event args.</param>
+        protected override void ItemsCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
+        {
+            base.ItemsCollectionChanged(sender, e);
+
+            var selected = this.SelectedItem;
+
+            switch (e.Action)
+            {
+                case NotifyCollectionChangedAction.Remove:
+                case NotifyCollectionChangedAction.Reset:
+                    if (e.OldItems.Contains(selected))
                     {
-                        return index;
+                        this.SelectedItem = null;
                     }
 
-                    ++index;
+                    break;
-                }
+                case NotifyCollectionChangedAction.Move:
+                    this.SelectedItem = this.Items.IndexOf(selected);
+                    break;
             }
-
-            return -1;
         }
 
-        protected int GetIndexOfItem(object item)
+        /// <summary>
+        /// Called when the selection on a child item changes.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        protected virtual void ItemIsSelectedChanged(RoutedEventArgs e)
         {
-            return GetIndexOfItem(this.Items, item);
+            var selectable = e.Source as ISelectable;
+
+            if (selectable != null && selectable != this && selectable.IsSelected)
+            {
+                var container = this.ItemContainerGenerator.GetItemForContainer((Control)selectable);
+
+                if (container != null)
+                {
+                    this.SelectedItem = container;
+                    e.Handled = true;
+                }
+            }
         }
 
+        /// <summary>
+        /// Moves the selection in the specified direction.
+        /// </summary>
+        /// <param name="direction">The direction.</param>
         protected virtual void MoveSelection(FocusNavigationDirection direction)
         {
-            if (this.SelectedItem != null)
+            var panel = this.Presenter?.Panel as INavigablePanel;
+            var selected = this.SelectedItem;
+            var container = selected != null ?
+                this.ItemContainerGenerator.GetContainerForItem(selected) :
+                null;
+
+            if (panel != null)
             {
-                int offset = 0;
+                var next = panel.GetControl(direction, container);
 
-                switch (direction)
+                if (next != null)
                 {
-                    case FocusNavigationDirection.Up:
+                    this.SelectedItem = this.ItemContainerGenerator.GetItemForContainer(next);
-                        offset = -1;
+                }
+            }
+            else
+            {
+                // TODO: Try doing a visual search?
+            }
+        }
+
+        /// <summary>
+        /// Called when a key is pressed within the control.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        protected override void OnKeyDown(KeyEventArgs e)
+        {
+            base.OnKeyDown(e);
+
+            if (!e.Handled)
+            {
+                switch (e.Key)
+                {
+                    case Key.Up:
+                        this.MoveSelection(FocusNavigationDirection.Up);
+                        break;
+                    case Key.Down:
+                        this.MoveSelection(FocusNavigationDirection.Down);
                         break;
-                    case FocusNavigationDirection.Down:
+                    case Key.Left:
-                        offset = 1;
+                        this.MoveSelection(FocusNavigationDirection.Left);
                         break;
+                    case Key.Right:
+                        this.MoveSelection(FocusNavigationDirection.Right);
+                        break;
+                    default:
+                        return;
                 }
 
-                if (offset != 0)
+                var selected = this.SelectedItem;
+
+                if (selected != null)
                 {
-                    var currentIndex = GetIndexOfItem(this.SelectedItem);
+                    var container = this.ItemContainerGenerator.GetContainerForItem(selected);
-                    var index = currentIndex + offset;
 
-                    if (index >= 0 && index < this.Items.Cast<object>().Count())
+                    if (container != null)
                     {
-                        this.SelectedItem = this.Items.Cast<object>().ElementAt(index);
+                        container.BringIntoView();
+                        FocusManager.Instance.Focus(container, true);
                     }
                 }
-            }
-        }
 
-        protected override void OnKeyDown(KeyEventArgs e)
+                e.Handled = true;
-        {
-            switch (e.Key)
-            {
-                case Key.Up:
-                    this.MoveSelection(FocusNavigationDirection.Up);
-                    break;
-                case Key.Down:
-                    this.MoveSelection(FocusNavigationDirection.Down);
-                    break;
-                case Key.Left:
-                    this.MoveSelection(FocusNavigationDirection.Left);
-                    break;
-                case Key.Right:
-                    this.MoveSelection(FocusNavigationDirection.Right);
-                    break;
             }
-
-            e.Handled = true;
         }
 
+        /// <summary>
+        /// Called when the pointer is pressed within the control.
+        /// </summary>
+        /// <param name="e">The event args.</param>
         protected override void OnPointerPressed(PointerPressEventArgs e)
         {
             IVisual source = (IVisual)e.Source;
@@ -128,12 +235,120 @@ namespace Perspex.Controls.Primitives
                 if (item != null)
                 {
                     this.SelectedItem = item;
+                    selectable.BringIntoView();
+                    FocusManager.Instance.Focus(selectable);
                 }
             }
 
             e.Handled = true;
         }
 
+        /// <summary>
+        /// Called when the control's template has been applied.
+        /// </summary>
+        protected override void OnTemplateApplied()
+        {
+            base.OnTemplateApplied();
+            this.SelectedItemChanged(this.SelectedItem);
+        }
+
+        /// <summary>
+        /// Provides coercion for the <see cref="SelectedIndex"/> property.
+        /// </summary>
+        /// <param name="o">The object on which the property has changed.</param>
+        /// <param name="value">The proposed value.</param>
+        /// <returns>The coerced value.</returns>
+        private static int CoerceSelectedIndex(PerspexObject o, int value)
+        {
+            var control = o as SelectingItemsControl;
+
+            if (control != null)
+            {
+                if (value < -1)
+                {
+                    return -1;
+                }
+                else if (value > -1)
+                {
+                    var items = control.Items;
+
+                    if (items != null)
+                    {
+                        var count = items.Count();
+                        return Math.Min(value, count - 1);
+                    }
+                    else
+                    {
+                        return -1;
+                    }
+                }
+            }
+
+            return value;
+        }
+
+        /// <summary>
+        /// Provides coercion for the <see cref="SelectedItem"/> property.
+        /// </summary>
+        /// <param name="o">The object on which the property has changed.</param>
+        /// <param name="value">The proposed value.</param>
+        /// <returns>The coerced value.</returns>
+        private static object CoerceSelectedItem(PerspexObject o, object value)
+        {
+            var control = o as SelectingItemsControl;
+
+            if (control != null)
+            {
+                if (value != null && (control.Items == null || control.Items.IndexOf(value) == -1))
+                {
+                    return null;
+                }
+            }
+
+            return value;
+        }
+
+        /// <summary>
+        /// Called when the <see cref="SelectedIndex"/> property changes.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        private static void SelectedIndexChanged(PerspexPropertyChangedEventArgs e)
+        {
+            var control = e.Sender as SelectingItemsControl;
+
+            if (control != null)
+            {
+                var index = (int)e.NewValue;
+
+                if (index == -1)
+                {
+                    control.SelectedItem = null;
+                }
+                else
+                {
+                    control.SelectedItem = control.Items.ElementAt((int)e.NewValue);
+                }
+            }
+        }
+
+        /// <summary>
+        /// Called when the <see cref="SelectedItem"/> property changes.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        private static void SelectedItemChanged(PerspexPropertyChangedEventArgs e)
+        {
+            var control = e.Sender as SelectingItemsControl;
+
+            if (control != null)
+            {
+                control.SelectedItemChanged(e.NewValue);
+            }
+        }
+
+        /// <summary>
+        /// Called when the <see cref="SelectedItem"/> property changes.
+        /// </summary>
+        /// <param name="selected">The new selected item.</param>
         private void SelectedItemChanged(object selected)
         {
             var containers = this.ItemContainerGenerator.GetAll()
@@ -143,10 +358,29 @@ namespace Perspex.Controls.Primitives
                 this.ItemContainerGenerator.GetContainerForItem(selected) :
                 null;
 
+            if (this.Presenter != null && this.Presenter.Panel != null)
+            {
+                KeyboardNavigation.SetTabOnceActiveElement(this.Presenter.Panel, selectedContainer);
+            }
+
             foreach (var item in containers)
             {
                 item.IsSelected = item == selectedContainer;
             }
+
+            if (selected == null)
+            {
+                this.SelectedIndex = -1;
+            }
+            else
+            {
+                var items = this.Items;
+
+                if (items != null)
+                {
+                    this.SelectedIndex = items.IndexOf(selected);
+                }
+            }
         }
     }
 }

Perspex.Controls/Primitives/TabStrip.cs

@@ -27,7 +27,8 @@ namespace Perspex.Controls.Primitives
 
         public TabStrip()
         {
-            this.BindTwoWay(SelectedTabProperty, this, SelectingItemsControl.SelectedItemProperty);
+            this.GetObservable(SelectedItemProperty).Subscribe(x => this.SelectedTab = x as TabItem);
+            this.GetObservable(SelectedTabProperty).Subscribe(x => this.SelectedItem = x as TabItem);
         }
 
         public TabItem SelectedTab

Perspex.Controls/Primitives/TemplatedControl.cs

@@ -13,7 +13,8 @@ namespace Perspex.Controls.Primitives
     using Perspex.Media;
     using Perspex.Styling;
     using Perspex.VisualTree;
-    using Splat;
+    using Serilog;
+    using Serilog.Core.Enrichers;
 
     public class TemplatedControl : Control, ITemplatedControl
     {
@@ -46,6 +47,8 @@ namespace Perspex.Controls.Primitives
 
         private bool templateApplied;
 
+        private ILogger templateLog;
+
         static TemplatedControl()
         {
             TemplateProperty.Changed.Subscribe(e =>
@@ -56,6 +59,16 @@ namespace Perspex.Controls.Primitives
             });
         }
 
+        public TemplatedControl()
+        {
+            this.templateLog = Log.ForContext(new[]
+            {
+                new PropertyEnricher("Area", "Template"),
+                new PropertyEnricher("SourceContext", this.GetType()),
+                new PropertyEnricher("Id", this.GetHashCode()),
+            });
+        }
+
         public Brush Background
         {
             get { return this.GetValue(BackgroundProperty); }
@@ -122,10 +135,7 @@ namespace Perspex.Controls.Primitives
 
                 if (this.Template != null)
                 {
-                    this.Log().Debug(
+                    this.templateLog.Verbose("Creating control template");
-                        "Creating template for {0} (#{1:x8})",
-                        this.GetType().Name,
-                        this.GetHashCode());
 
                     var child = this.Template.Build(this);
                     this.SetTemplatedParent(child);
@@ -166,7 +176,7 @@ namespace Perspex.Controls.Primitives
             if (child != null)
             {
                 child.Measure(availableSize);
-                return child.DesiredSize.Value;
+                return child.DesiredSize;
             }
 
             return new Size();

Perspex.Controls/Primitives/Track.cs

@@ -103,11 +103,11 @@ namespace Perspex.Controls.Primitives
 
                 if (this.Orientation == Orientation.Horizontal)
                 {
-                    return new Size(0, thumb.DesiredSize.Value.Height);
+                    return new Size(0, thumb.DesiredSize.Height);
                 }
                 else
                 {
-                    return new Size(thumb.DesiredSize.Value.Width, 0);
+                    return new Size(thumb.DesiredSize.Width, 0);
                 }
             }
 

Perspex.Controls/RowDefinitions.cs

@@ -6,9 +6,19 @@
 
 namespace Perspex.Controls
 {
+    using System.Linq;
     using Perspex.Collections;
+    using Perspex.Controls.Parsers;
 
     public class RowDefinitions : PerspexList<RowDefinition>
     {
+        public RowDefinitions()
+        {
+        }
+
+        public RowDefinitions(string s)
+        {
+            this.AddRange(GridLengthsParser.Parse(s).Select(x => new RowDefinition(x)));
+        }
     }
 }

Perspex.Controls/Shapes/Ellipse.cs

@@ -20,8 +20,7 @@ namespace Perspex.Controls.Shapes
             {
                 if (this.geometry == null || this.geometrySize != this.Bounds.Size)
                 {
-                    var rect = new Rect(0, 0, this.Bounds.Size.Width, this.Bounds.Size.Height);
+                    var rect = new Rect(this.Bounds.Size).Deflate(this.StrokeThickness);
-                    rect = rect.Deflate(this.StrokeThickness / 2);
                     this.geometry = new EllipseGeometry(rect);
                     this.geometrySize = this.Bounds.Size;
                 }

Perspex.Controls/Shapes/Rectangle.cs

@@ -20,7 +20,8 @@ namespace Perspex.Controls.Shapes
             {
                 if (this.geometry == null || this.geometrySize != this.Bounds.Size)
                 {
-                    this.geometry = new RectangleGeometry(new Rect(0, 0, this.Bounds.Size.Width, this.Bounds.Size.Height));
+                    var rect = new Rect(this.Bounds.Size).Deflate(this.StrokeThickness);
+                    this.geometry = new RectangleGeometry(rect);
                     this.geometrySize = this.Bounds.Size;
                 }
 

Perspex.Controls/StackPanel.cs

@@ -7,10 +7,8 @@
 namespace Perspex.Controls
 {
     using System;
-    using System.Collections.Generic;
     using System.Linq;
-    using System.Text;
+    using Perspex.Input;
-    using System.Threading.Tasks;
 
     public enum Orientation
     {
@@ -18,7 +16,7 @@ namespace Perspex.Controls
         Horizontal,
     }
 
-    public class StackPanel : Panel
+    public class StackPanel : Panel, INavigablePanel
     {
         public static readonly PerspexProperty<double> GapProperty =
             PerspexProperty.Register<StackPanel, double>("Gap");
@@ -38,6 +36,49 @@ namespace Perspex.Controls
             set { this.SetValue(OrientationProperty, value); }
         }
 
+        Control INavigablePanel.GetControl(FocusNavigationDirection direction, Control from)
+        {
+            var horiz = this.Orientation == Orientation.Horizontal;
+            int index = this.Children.IndexOf(from);
+
+            switch (direction)
+            {
+                case FocusNavigationDirection.First:
+                    index = 0;
+                    break;
+                case FocusNavigationDirection.Last:
+                    index = this.Children.Count - 1;
+                    break;
+                case FocusNavigationDirection.Next:
+                    ++index;
+                    break;
+                case FocusNavigationDirection.Previous:
+                    ++index;
+                    break;
+                case FocusNavigationDirection.Left:
+                    index = horiz ? index - 1 : -1;
+                    break;
+                case FocusNavigationDirection.Right:
+                    index = horiz ? index + 1 : -1;
+                    break;
+                case FocusNavigationDirection.Up:
+                    index = horiz ? -1 : index - 1;
+                    break;
+                case FocusNavigationDirection.Down:
+                    index = horiz ? -1 : index + 1;
+                    break;
+            }
+
+            if (index >= 0 && index < this.Children.Count)
+            {
+                return this.Children[index];
+            }
+            else
+            {
+                return null;
+            }
+        }
+
         protected override Size MeasureOverride(Size availableSize)
         {
             double childAvailableWidth = double.PositiveInfinity;
@@ -75,7 +116,7 @@ namespace Perspex.Controls
             foreach (Control child in this.Children)
             {
                 child.Measure(new Size(childAvailableWidth, childAvailableHeight));
-                Size size = child.DesiredSize.Value;
+                Size size = child.DesiredSize;
 
                 if (Orientation == Orientation.Vertical)
                 {
@@ -109,8 +150,8 @@ namespace Perspex.Controls
 
             foreach (Control child in this.Children)
             {
-                double childWidth = child.DesiredSize.Value.Width;
+                double childWidth = child.DesiredSize.Width;
-                double childHeight = child.DesiredSize.Value.Height;
+                double childHeight = child.DesiredSize.Height;
 
                 if (Orientation == Orientation.Vertical)
                 {