diff --git a/Perspex.Base/Perspex.Base.csproj b/Perspex.Base/Perspex.Base.csproj
index 6547b5bf99..2cb1dd0369 100644
--- a/Perspex.Base/Perspex.Base.csproj
+++ b/Perspex.Base/Perspex.Base.csproj
@@ -37,6 +37,7 @@
     <Compile Include="Binding.cs" />
     <Compile Include="Contract.cs" />
     <Compile Include="IDescription.cs" />
+    <Compile Include="PerspexListExtensions.cs" />
     <Compile Include="IObservableDescription.cs" />
     <Compile Include="IReadOnlyPerspexList.cs" />
     <Compile Include="PerspexList.cs" />
diff --git a/Perspex.Base/PerspexListExtensions.cs b/Perspex.Base/PerspexListExtensions.cs
new file mode 100644
index 0000000000..c62a8bfad0
--- /dev/null
+++ b/Perspex.Base/PerspexListExtensions.cs
@@ -0,0 +1,106 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Specialized;
+using System.ComponentModel;
+using System.Linq;
+using System.Reactive.Disposables;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Perspex
+{
+    public static class PerspexListExtensions
+    {
+        public static IDisposable ForEachItem<T>(
+            this IReadOnlyPerspexList<T> collection,
+            Action<T> added,
+            Action<T> removed)
+        {
+            NotifyCollectionChangedEventHandler handler = (_, e) =>
+            {
+                switch (e.Action)
+                {
+                    case NotifyCollectionChangedAction.Add:
+                        foreach (T i in e.NewItems)
+                        {
+                            added(i);
+                        }
+                        break;
+
+                    case NotifyCollectionChangedAction.Replace:
+                        foreach (T i in e.OldItems)
+                        {
+                            removed(i);
+                        }
+
+                        foreach (T i in e.NewItems)
+                        {
+                            added(i);
+                        }
+
+                        break;
+
+                    case NotifyCollectionChangedAction.Remove:
+                        foreach (T i in e.OldItems)
+                        {
+                            removed(i);
+                        }
+                        break;
+                }
+            };
+
+            foreach (T i in collection)
+            {
+                added(i);
+            }
+
+            collection.CollectionChanged += handler;
+
+            System.Diagnostics.Debug.WriteLine("Tracked " + collection.GetHashCode());
+
+            return Disposable.Create(() => collection.CollectionChanged -= handler);
+        }
+
+        public static IDisposable TrackItemPropertyChanged<T>(
+            this IReadOnlyPerspexList<T> collection,
+            Action<Tuple<object, PropertyChangedEventArgs>> callback)
+        {
+            List<INotifyPropertyChanged> tracked = new List<INotifyPropertyChanged>();
+
+            PropertyChangedEventHandler handler = (s, e) =>
+            {
+                callback(Tuple.Create(s, e));
+            };
+
+            collection.ForEachItem(
+                x =>
+                {
+                    var inpc = x as INotifyPropertyChanged;
+
+                    if (inpc != null)
+                    {
+                        inpc.PropertyChanged += handler;
+                        tracked.Add(inpc);
+                    }
+                },
+                x =>
+                {
+                    var inpc = x as INotifyPropertyChanged;
+
+                    if (inpc != null)
+                    {
+                        inpc.PropertyChanged -= handler;
+                        tracked.Remove(inpc);
+                    }
+                });
+
+            return Disposable.Create(() =>
+            {
+                foreach (var i in tracked)
+                {
+                    i.PropertyChanged -= handler;
+                }
+            });
+        }
+    }
+}
diff --git a/Perspex.Base/PerspexObject.cs b/Perspex.Base/PerspexObject.cs
index c2d0387763..b5febbdbdd 100644
--- a/Perspex.Base/PerspexObject.cs
+++ b/Perspex.Base/PerspexObject.cs
@@ -8,6 +8,7 @@ namespace Perspex
 {
     using System;
     using System.Collections.Generic;
+    using System.ComponentModel;
     using System.Linq;
     using System.Reactive.Linq;
     using System.Reflection;
@@ -56,7 +57,7 @@ namespace Perspex
     /// <remarks>
     /// This class is analogous to DependencyObject in WPF.
     /// </remarks>
-    public class PerspexObject : IEnableLogger
+    public class PerspexObject : INotifyPropertyChanged, IEnableLogger
     {
         /// <summary>
         /// The registered properties by type.
@@ -76,10 +77,24 @@ namespace Perspex
             new Dictionary<PerspexProperty, PriorityValue>();
 
         /// <summary>
-        /// Raised when a <see cref="PerspexProperty"/> value changes on this object/
+        /// Event handler for <see cref="INotifyPropertyChanged"/> implementation.
+        /// </summary>
+        private PropertyChangedEventHandler inpcChanged;
+
+        /// <summary>
+        /// Raised when a <see cref="PerspexProperty"/> value changes on this object.
         /// </summary>
         public event EventHandler<PerspexPropertyChangedEventArgs> PropertyChanged;
 
+        /// <summary>
+        /// Raised when a <see cref="PerspexProperty"/> value changes on this object.
+        /// </summary>
+        event PropertyChangedEventHandler INotifyPropertyChanged.PropertyChanged
+        {
+            add { this.inpcChanged += value; }
+            remove { this.inpcChanged -= value; }
+        }
+
         /// <summary>
         /// Gets or sets the parent object that inherited <see cref="PerspexProperty"/> values 
         /// are inherited from.
@@ -646,6 +661,12 @@ namespace Perspex
                 property.NotifyChanged(e);
                 this.PropertyChanged(this, e);
             }
+
+            if (this.inpcChanged != null)
+            {
+                PropertyChangedEventArgs e = new PropertyChangedEventArgs(property.Name);
+                this.inpcChanged(this, e);
+            }
         }
     }
 }
diff --git a/Perspex.Controls/Button.cs b/Perspex.Controls/Button.cs
index 95462d27fc..c6ef99954f 100644
--- a/Perspex.Controls/Button.cs
+++ b/Perspex.Controls/Button.cs
@@ -34,7 +34,10 @@ namespace Perspex.Controls
 
                 if (this.Classes.Contains(":pointerover"))
                 {
-                    RoutedEventArgs click = new RoutedEventArgs(ClickEvent, this);
+                    RoutedEventArgs click = new RoutedEventArgs
+                    {
+                        RoutedEvent = ClickEvent,
+                    };
                     this.RaiseEvent(click);
                 }
             };
diff --git a/Perspex.Controls/Grid.cs b/Perspex.Controls/Grid.cs
index 4cc626b139..617cc50982 100644
--- a/Perspex.Controls/Grid.cs
+++ b/Perspex.Controls/Grid.cs
@@ -27,25 +27,64 @@ namespace Perspex.Controls
         public static readonly PerspexProperty<int> RowSpanProperty =
             PerspexProperty.RegisterAttached<Grid, Control, int>("RowSpan", 1);
 
+        private ColumnDefinitions columnDefinitions;
+
+        private RowDefinitions rowDefinitions;
+
         private Segment[,] rowMatrix;
+
         private Segment[,] colMatrix;
 
         public Grid()
         {
-            this.ColumnDefinitions = new ColumnDefinitions();
-            this.RowDefinitions = new RowDefinitions();
         }
 
         public ColumnDefinitions ColumnDefinitions
         {
-            get;
-            set;
+            get
+            {
+                if (this.columnDefinitions == null)
+                {
+                    this.ColumnDefinitions = new ColumnDefinitions();
+                }
+
+                return this.columnDefinitions;
+            }
+
+            set
+            {
+                if (this.columnDefinitions != null)
+                {
+                    throw new NotSupportedException("Reassigning ColumnDefinitions not yet implemented.");
+                }
+
+                this.columnDefinitions = value;
+                this.columnDefinitions.TrackItemPropertyChanged(_ => this.InvalidateMeasure());
+            }
         }
 
         public RowDefinitions RowDefinitions
         {
-            get;
-            set;
+            get
+            {
+                if (this.rowDefinitions == null)
+                {
+                    this.RowDefinitions = new RowDefinitions();
+                }
+
+                return this.rowDefinitions;
+            }
+
+            set
+            {
+                if (this.rowDefinitions != null)
+                {
+                    throw new NotSupportedException("Reassigning RowDefinitions not yet implemented.");
+                }
+
+                this.rowDefinitions = value;
+                this.rowDefinitions.TrackItemPropertyChanged(_ => this.InvalidateMeasure());
+            }
         }
 
         public static int GetColumn(PerspexObject element)
diff --git a/Perspex.Controls/GridSplitter.cs b/Perspex.Controls/GridSplitter.cs
new file mode 100644
index 0000000000..93d62c346f
--- /dev/null
+++ b/Perspex.Controls/GridSplitter.cs
@@ -0,0 +1,34 @@
+// -----------------------------------------------------------------------
+// <copyright file="GridSplitter.cs" company="Steven Kirk">
+// Copyright 2013 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Controls
+{
+    using System;
+    using Perspex.Controls.Primitives;
+    using Perspex.Input;
+
+    public class GridSplitter : Thumb
+    {
+        private Grid grid;
+
+        protected override void OnDragDelta(VectorEventArgs e)
+        {
+            int col = this.GetValue(Grid.ColumnProperty);
+
+            if (grid != null && col > 0)
+            {
+                grid.ColumnDefinitions[col - 1].Width = new GridLength(
+                    grid.ColumnDefinitions[col - 1].ActualWidth + e.Vector.X,
+                    GridUnitType.Pixel);
+            }
+        }
+
+        protected override void OnVisualParentChanged(Visual oldParent)
+        {
+            this.grid = this.GetVisualParent<Grid>();
+        }
+    }
+}
diff --git a/Perspex.Controls/Perspex.Controls.csproj b/Perspex.Controls/Perspex.Controls.csproj
index ce2217bd1e..55b51c2ec4 100644
--- a/Perspex.Controls/Perspex.Controls.csproj
+++ b/Perspex.Controls/Perspex.Controls.csproj
@@ -40,6 +40,7 @@
     <Compile Include="ColumnDefinition.cs" />
     <Compile Include="ColumnDefinitions.cs" />
     <Compile Include="ContentControl.cs" />
+    <Compile Include="GridSplitter.cs" />
     <Compile Include="Presenters\ContentPresenter.cs" />
     <Compile Include="Control.cs" />
     <Compile Include="ControlExtensions.cs" />
@@ -65,6 +66,7 @@
     <Compile Include="ItemsPanelTemplate.cs" />
     <Compile Include="Presenters\ItemsPresenter.cs" />
     <Compile Include="Panel.cs" />
+    <Compile Include="Primitives\Thumb.cs" />
     <Compile Include="RowDefinition.cs" />
     <Compile Include="RowDefinitions.cs" />
     <Compile Include="Primitives\SelectingItemsControl.cs" />
diff --git a/Perspex.Controls/Primitives/Thumb.cs b/Perspex.Controls/Primitives/Thumb.cs
new file mode 100644
index 0000000000..5c9adfcb26
--- /dev/null
+++ b/Perspex.Controls/Primitives/Thumb.cs
@@ -0,0 +1,108 @@
+// -----------------------------------------------------------------------
+// <copyright file="Thumb.cs" company="Steven Kirk">
+// Copyright 2014 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Controls.Primitives
+{
+    using System;
+    using Perspex.Input;
+    using Perspex.Interactivity;
+
+    public class Thumb : TemplatedControl
+    {
+        public static readonly RoutedEvent<VectorEventArgs> DragStartedEvent =
+            RoutedEvent.Register<Thumb, VectorEventArgs>("DragStarted", RoutingStrategy.Bubble);
+
+        public static readonly RoutedEvent<VectorEventArgs> DragDeltaEvent =
+            RoutedEvent.Register<Thumb, VectorEventArgs>("DragDelta", RoutingStrategy.Bubble);
+
+        public static readonly RoutedEvent<VectorEventArgs> DragCompletedEvent =
+            RoutedEvent.Register<Thumb, VectorEventArgs>("DragCompleted", RoutingStrategy.Bubble);
+
+        Point? lastPoint;
+
+        public Thumb()
+        {
+            this.DragStarted += (_, e) => this.OnDragStarted(e);
+            this.DragDelta += (_, e) => this.OnDragDelta(e);
+            this.DragCompleted += (_, e) => this.OnDragCompleted(e);
+        }
+
+        public event EventHandler<VectorEventArgs> DragStarted
+        {
+            add { this.AddHandler(DragStartedEvent, value); }
+            remove { this.RemoveHandler(DragStartedEvent, value); }
+        }
+
+        public event EventHandler<VectorEventArgs> DragDelta
+        {
+            add { this.AddHandler(DragDeltaEvent, value); }
+            remove { this.RemoveHandler(DragDeltaEvent, value); }
+        }
+
+        public event EventHandler<VectorEventArgs> DragCompleted
+        {
+            add { this.AddHandler(DragCompletedEvent, value); }
+            remove { this.RemoveHandler(DragCompletedEvent, value); }
+        }
+
+        protected virtual void OnDragStarted(VectorEventArgs e)
+        {
+        }
+
+        protected virtual void OnDragDelta(VectorEventArgs e)
+        {
+        }
+
+        protected virtual void OnDragCompleted(VectorEventArgs e)
+        {
+        }
+
+        protected override void OnPointerMoved(PointerEventArgs e)
+        {
+            if (this.lastPoint.HasValue)
+            {
+                var ev = new VectorEventArgs
+                {
+                    RoutedEvent = DragDeltaEvent,
+                    Vector = e.GetPosition(this) - this.lastPoint.Value,
+                };
+
+                this.RaiseEvent(ev);
+            }
+        }
+
+        protected override void OnPointerPressed(PointerEventArgs e)
+        {
+            e.Device.Capture(this);
+            this.lastPoint = e.GetPosition(this);
+
+            var ev = new VectorEventArgs
+            {
+                RoutedEvent = DragStartedEvent,
+                Vector = (Vector)this.lastPoint,
+            };
+
+            this.RaiseEvent(ev);
+        }
+
+        protected override void OnPointerReleased(PointerEventArgs e)
+        {
+            if (this.lastPoint.HasValue)
+            {
+                e.Device.Capture(null);
+                this.lastPoint = null;
+
+                var ev = new VectorEventArgs
+                {
+                    RoutedEvent = DragCompletedEvent,
+                    Vector = (Vector)e.GetPosition(this),
+                };
+
+                this.RaiseEvent(ev);
+            }
+        }
+    }
+}
diff --git a/Perspex.Diagnostics/DevTools.cs b/Perspex.Diagnostics/DevTools.cs
index 682b71753f..17f35f08a2 100644
--- a/Perspex.Diagnostics/DevTools.cs
+++ b/Perspex.Diagnostics/DevTools.cs
@@ -46,7 +46,13 @@ namespace Perspex.Diagnostics
                     .Where(x => x != null)
                     .Cast<VisualTreeNode>()
                     .Select(x => new ControlDetails(x.Visual)),
+                [Grid.ColumnProperty] = 2,
+            };
+
+            var splitter = new GridSplitter
+            {
                 [Grid.ColumnProperty] = 1,
+                Width = 4,
             };
 
             this.Content = new Grid
@@ -54,11 +60,13 @@ namespace Perspex.Diagnostics
                 ColumnDefinitions = new ColumnDefinitions
                 {
                     new ColumnDefinition(1, GridUnitType.Star),
+                    new ColumnDefinition(4, GridUnitType.Pixel),
                     new ColumnDefinition(3, GridUnitType.Star),
                 },
                 Children = new Controls
                 {
                     treeView,
+                    splitter,
                     detailsView,
                 }
             };
diff --git a/Perspex.Input/InputElement.cs b/Perspex.Input/InputElement.cs
index 0fda582268..4c0038aae4 100644
--- a/Perspex.Input/InputElement.cs
+++ b/Perspex.Input/InputElement.cs
@@ -39,6 +39,9 @@ namespace Perspex.Input
         public static readonly RoutedEvent<PointerEventArgs> PointerLeaveEvent =
             RoutedEvent.Register<InputElement, PointerEventArgs>("PointerLeave", RoutingStrategy.Direct);
 
+        public static readonly RoutedEvent<PointerEventArgs> PointerMovedEvent =
+            RoutedEvent.Register<InputElement, PointerEventArgs>("PointerMove", RoutingStrategy.Bubble);
+
         public static readonly RoutedEvent<PointerEventArgs> PointerPressedEvent =
             RoutedEvent.Register<InputElement, PointerEventArgs>("PointerPressed", RoutingStrategy.Bubble);
 
@@ -53,6 +56,7 @@ namespace Perspex.Input
             this.PreviewKeyDown += (_, e) => this.OnPreviewKeyDown(e);
             this.PointerEnter += (_, e) => this.OnPointerEnter(e);
             this.PointerLeave += (_, e) => this.OnPointerLeave(e);
+            this.PointerMoved += (_, e) => this.OnPointerMoved(e);
             this.PointerPressed += (_, e) => this.OnPointerPressed(e);
             this.PointerReleased += (_, e) => this.OnPointerReleased(e);
         }
@@ -93,6 +97,12 @@ namespace Perspex.Input
             remove { this.RemoveHandler(PointerLeaveEvent, value); }
         }
 
+        public event EventHandler<PointerEventArgs> PointerMoved
+        {
+            add { this.AddHandler(PointerMovedEvent, value); }
+            remove { this.RemoveHandler(PointerMovedEvent, value); }
+        }
+
         public event EventHandler<PointerEventArgs> PointerPressed
         {
             add { this.AddHandler(PointerPressedEvent, value); }
@@ -156,6 +166,10 @@ namespace Perspex.Input
             this.IsPointerOver = false;
         }
 
+        protected virtual void OnPointerMoved(PointerEventArgs e)
+        {
+        }
+
         protected virtual void OnPointerPressed(PointerEventArgs e)
         {
         }
diff --git a/Perspex.Input/MouseDevice.cs b/Perspex.Input/MouseDevice.cs
index 89fa0cb8cd..4ef82f543b 100644
--- a/Perspex.Input/MouseDevice.cs
+++ b/Perspex.Input/MouseDevice.cs
@@ -81,9 +81,12 @@ namespace Perspex.Input
 
         private void MouseMove(IMouseDevice device, IVisual visual, Point p)
         {
+            IInteractive source;
+
             if (this.Captured == null)
             {
                 this.InputManager.SetPointerOver(this, visual, p);
+                source = visual as IInteractive;
             }
             else
             {
@@ -95,6 +98,18 @@ namespace Perspex.Input
                 }
 
                 this.InputManager.SetPointerOver(this, this.Captured, p - offset);
+                source = this.Captured as IInteractive;
+            }
+
+            if (source != null)
+            {
+                source.RaiseEvent(new PointerEventArgs
+                {
+                    Device = this,
+                    RoutedEvent = InputElement.PointerMovedEvent,
+                    OriginalSource = source,
+                    Source = source,
+                });
             }
         }
 
diff --git a/Perspex.Input/Perspex.Input.csproj b/Perspex.Input/Perspex.Input.csproj
index d9282a1148..35d8451ee4 100644
--- a/Perspex.Input/Perspex.Input.csproj
+++ b/Perspex.Input/Perspex.Input.csproj
@@ -66,6 +66,7 @@
     <Compile Include="IPointerDevice.cs" />
     <Compile Include="Key.cs" />
     <Compile Include="KeyboardDevice.cs" />
+    <Compile Include="VectorEventArgs.cs" />
     <Compile Include="KeyEventArgs.cs" />
     <Compile Include="MouseDevice.cs" />
     <Compile Include="PointerEventArgs.cs" />
diff --git a/Perspex.Input/VectorEventArgs.cs b/Perspex.Input/VectorEventArgs.cs
new file mode 100644
index 0000000000..be6cf7c1e9
--- /dev/null
+++ b/Perspex.Input/VectorEventArgs.cs
@@ -0,0 +1,16 @@
+// -----------------------------------------------------------------------
+// <copyright file="VectorEventArgs.cs" company="Steven Kirk">
+// Copyright 2013 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Input
+{
+    using System;
+    using Perspex.Interactivity;
+
+    public class VectorEventArgs : RoutedEventArgs
+    {
+        public Vector Vector { get; set; }
+    }
+}
diff --git a/Perspex.Interactivity/Interactive.cs b/Perspex.Interactivity/Interactive.cs
index f9c16d84f5..509ffcedd5 100644
--- a/Perspex.Interactivity/Interactive.cs
+++ b/Perspex.Interactivity/Interactive.cs
@@ -59,6 +59,9 @@ namespace Perspex.Interactivity
         {
             Contract.Requires<NullReferenceException>(e != null);
 
+            e.Source = e.Source ?? this;
+            e.OriginalSource = e.OriginalSource ?? this;
+
             if (!e.Handled)
             {
                 switch (e.RoutedEvent.RoutingStrategy)
diff --git a/Perspex.Interactivity/RoutedEventArgs.cs b/Perspex.Interactivity/RoutedEventArgs.cs
index 23d97b9818..9e54d1d585 100644
--- a/Perspex.Interactivity/RoutedEventArgs.cs
+++ b/Perspex.Interactivity/RoutedEventArgs.cs
@@ -10,21 +10,6 @@ namespace Perspex.Interactivity
 
     public class RoutedEventArgs : EventArgs
     {
-        public RoutedEventArgs()
-        {
-        }
-
-        public RoutedEventArgs(RoutedEvent routedEvent)
-        {
-            this.RoutedEvent = routedEvent;
-        }
-
-        public RoutedEventArgs(RoutedEvent routedEvent, IInteractive source)
-        {
-            this.RoutedEvent = routedEvent;
-            this.Source = source;
-        }
-
         public bool Handled { get; set; }
 
         public IInteractive OriginalSource { get; set; }
diff --git a/Perspex.Themes.Default/DefaultTheme.cs b/Perspex.Themes.Default/DefaultTheme.cs
index e4f7f1ee5f..bf33d21b2e 100644
--- a/Perspex.Themes.Default/DefaultTheme.cs
+++ b/Perspex.Themes.Default/DefaultTheme.cs
@@ -15,6 +15,7 @@ namespace Perspex.Themes.Default
             this.Add(new ButtonStyle());
             this.Add(new CheckBoxStyle());
             this.Add(new ContentControlStyle());
+            this.Add(new GridSplitterStyle());
             this.Add(new ItemsControlStyle());
             this.Add(new TabControlStyle());
             this.Add(new TabItemStyle());
diff --git a/Perspex.Themes.Default/GridSplitterStyle.cs b/Perspex.Themes.Default/GridSplitterStyle.cs
new file mode 100644
index 0000000000..99cb0d04aa
--- /dev/null
+++ b/Perspex.Themes.Default/GridSplitterStyle.cs
@@ -0,0 +1,42 @@
+// -----------------------------------------------------------------------
+// <copyright file="GridSplitterStyle.cs" company="Steven Kirk">
+// Copyright 2014 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Themes.Default
+{
+    using System.Linq;
+    using Perspex.Controls;
+    using Perspex.Controls.Presenters;
+    using Perspex.Media;
+    using Perspex.Styling;
+
+    public class GridSplitterStyle : Styles
+    {
+        public GridSplitterStyle()
+        {
+            this.AddRange(new[]
+            {
+                new Style(x => x.OfType<GridSplitter>())
+                {
+                    Setters = new[]
+                    {
+                        new Setter(GridSplitter.TemplateProperty, ControlTemplate.Create<GridSplitter>(this.Template)),
+                        new Setter(GridSplitter.WidthProperty, 4),
+                    },
+                },
+            });
+        }
+
+        private Control Template(GridSplitter control)
+        {
+            Border border = new Border
+            {
+                [~Border.BackgroundProperty] = control[~GridSplitter.BackgroundProperty],
+            };
+
+            return border;
+        }
+    }
+}
diff --git a/Perspex.Themes.Default/Perspex.Themes.Default.csproj b/Perspex.Themes.Default/Perspex.Themes.Default.csproj
index 30dd73a5f5..e436a1f65c 100644
--- a/Perspex.Themes.Default/Perspex.Themes.Default.csproj
+++ b/Perspex.Themes.Default/Perspex.Themes.Default.csproj
@@ -66,6 +66,7 @@
     </ProjectReference>
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="GridSplitterStyle.cs" />
     <Compile Include="ButtonStyle.cs" />
     <Compile Include="CheckBoxStyle.cs" />
     <Compile Include="ContentControlStyle.cs" />