Pass the device in PointerEventArgs.

Perspex.Windows/Input/MouseDevice.cs

@@ -6,9 +6,22 @@
 
 namespace Perspex.Windows.Input
 {
+    using System;
+    using System.Reactive.Disposables;
     using Perspex.Input;
 
-    public class MouseDevice : IInputDevice
+    public class MouseDevice : IMouseDevice
     {
+        public IVisual Captured
+        {
+            get;
+            private set;
+        }
+
+        public IDisposable Capture(IVisual visual)
+        {
+            this.Captured = visual;
+            return Disposable.Create(() => this.Captured = null);
+        }
     }
 }

Perspex/Controls/Control.cs

@@ -220,7 +220,7 @@ namespace Perspex.Controls
         public bool IsPointerOver
         {
             get { return this.GetValue(IsPointerOverProperty); }
-            set { this.SetValue(IsPointerOverProperty, value); }
+            internal set { this.SetValue(IsPointerOverProperty, value); }
         }
 
         public HorizontalAlignment HorizontalAlignment

Perspex/Input/IInputDevice.cs

@@ -1,17 +1,11 @@
 // -----------------------------------------------------------------------
 // <copyright file="IInputDevice.cs" company="Steven Kirk">
-// Copyright 2013 MIT Licence. See licence.md for more information.
+// Copyright 2014 MIT Licence. See licence.md for more information.
 // </copyright>
 // -----------------------------------------------------------------------
 
 namespace Perspex.Input
 {
-    using System;
-    using System.Collections.Generic;
-    using System.Linq;
-    using System.Text;
-    using System.Threading.Tasks;
-
     public interface IInputDevice
     {
     }

Perspex/Input/IMouseDevice.cs

@@ -0,0 +1,14 @@
+// -----------------------------------------------------------------------
+// <copyright file="IMouseDevice.cs" company="Steven Kirk">
+// Copyright 2014 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Input
+{
+    using System;
+
+    public interface IMouseDevice : IPointerDevice
+    {
+    }
+}

Perspex/Input/IPointerDevice.cs

@@ -0,0 +1,17 @@
+// -----------------------------------------------------------------------
+// <copyright file="IPointerDevice.cs" company="Steven Kirk">
+// Copyright 2014 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Input
+{
+    using System;
+
+    public interface IPointerDevice : IInputDevice
+    {
+        IVisual Captured { get; }
+
+        IDisposable Capture(IVisual visual);
+    }
+}

Perspex/Input/InputManager.cs

@@ -29,10 +29,10 @@ namespace Perspex.Input
                     this.MouseMove((IVisual)e.Root, e.Position);
                     break;
                 case RawMouseEventType.LeftButtonDown:
-                    this.MouseDown((IVisual)e.Root, e.Position);
+                    this.MouseDown((IMouseDevice)e.Device, (IVisual)e.Root, e.Position);
                     break;
                 case RawMouseEventType.LeftButtonUp:
-                    this.MouseUp((IVisual)e.Root, e.Position);
+                    this.MouseUp((IMouseDevice)e.Device, (IVisual)e.Root, e.Position);
                     break;
             }
         }
@@ -52,7 +52,7 @@ namespace Perspex.Input
             }
         }
 
-        private void MouseDown(IVisual visual, Point p)
+        private void MouseDown(IMouseDevice device, IVisual visual, Point p)
         {
             IVisual hit = visual.GetVisualAt(p);
 
@@ -64,6 +64,7 @@ namespace Perspex.Input
                 {
                     source.RaiseEvent(new PointerEventArgs
                     {
+                        Device = device,
                         RoutedEvent = Control.PointerPressedEvent,
                         OriginalSource = source,
                         Source = source,
@@ -72,7 +73,7 @@ namespace Perspex.Input
             }
         }
 
-        private void MouseUp(IVisual visual, Point p)
+        private void MouseUp(IMouseDevice device, IVisual visual, Point p)
         {
             IVisual hit = visual.GetVisualAt(p);
 
@@ -84,6 +85,7 @@ namespace Perspex.Input
                 {
                     source.RaiseEvent(new PointerEventArgs
                     {
+                        Device = device,
                         RoutedEvent = Control.PointerReleasedEvent,
                         OriginalSource = source,
                         Source = source,

Perspex/Input/PointerEventArgs.cs

@@ -10,5 +10,6 @@ namespace Perspex.Input
 
     public class PointerEventArgs : RoutedEventArgs
     {
+        public IPointerDevice Device { get; set; }
     }
 }

Perspex/Perspex.csproj

@@ -73,6 +73,8 @@
     <Compile Include="Controls\LogicalChildren.cs" />
     <Compile Include="Controls\Panel.cs" />
     <Compile Include="Controls\StackPanel.cs" />
+    <Compile Include="Input\IMouseDevice.cs" />
+    <Compile Include="Input\IPointerDevice.cs" />
     <Compile Include="Input\IInputDevice.cs" />
     <Compile Include="Input\IInputManager.cs" />
     <Compile Include="Input\InputManager.cs" />