Separated visual and logical tree into interfaces.

IVisual and ILogical, duh.

Perspex.UnitTests/Perspex.UnitTests.csproj

@@ -75,7 +75,6 @@
     <Compile Include="Styling\SelectorTests_Class.cs" />
     <Compile Include="Styling\SelectorTests_Id.cs" />
     <Compile Include="Styling\SelectorTests_OfType.cs" />
-    <Compile Include="Styling\SelectorTests_InTemplateOf.cs" />
     <Compile Include="Styling\TestControlBase.cs" />
   </ItemGroup>
   <ItemGroup>

Perspex.UnitTests/Styling/SelectorTests_Id.cs

@@ -44,15 +44,6 @@ namespace Perspex.UnitTests.Styling
             CollectionAssert.AreEqual(new[] { false }, target.GetActivator().Take(1).ToEnumerable().ToArray());
         }
 
-        [TestMethod]
-        public void Id_Matches_Control_With_TemplatedParent_After_InTemplateOf()
-        {
-            var control = new Control1 { Id = "foo", TemplatedParent = new TemplatedControl1() };
-            var target = control.Select().InTemplateOf<TemplatedControl1>().Id("foo");
-
-            CollectionAssert.AreEqual(new[] { true }, target.GetActivator().Take(1).ToEnumerable().ToArray());
-        }
-
         [TestMethod]
         public void When_Id_Matches_Control_Other_Selectors_Are_Subscribed()
         {

Perspex.Windows/Renderer.cs

@@ -71,7 +71,7 @@ namespace Perspex.Windows
         /// Renders the specified visual.
         /// </summary>
         /// <param name="visual">The visual to render.</param>
-        public void Render(Visual visual)
+        public void Render(IVisual visual)
         {
             using (DrawingContext context = new DrawingContext(this.renderTarget, this.DirectWriteFactory))
             {
@@ -94,7 +94,7 @@ namespace Perspex.Windows
         /// </summary>
         /// <param name="visual">The visual to render.</param>
         /// <param name="context">The drawing context.</param>
-        private void Render(Visual visual, DrawingContext context)
+        private void Render(IVisual visual, DrawingContext context)
         {
             visual.Render(context);
 

Perspex.Windows/Window.cs

@@ -164,7 +164,7 @@ namespace Perspex.Windows
                 control.IsMouseOver = visual.Bounds.Contains(p);
             }
 
-            foreach (Visual child in visual.VisualChildren)
+            foreach (Visual child in ((IVisual)visual).VisualChildren)
             {
                 this.MouseMove(child, p - visual.Bounds.Position);
             }

Perspex/ControlTemplate.cs

@@ -46,7 +46,7 @@ namespace Perspex
 
             control.TemplatedParent = templatedParent;
 
-            foreach (Control child in control.VisualChildren.OfType<Control>())
+            foreach (Control child in ((IVisual)control).VisualChildren.OfType<Control>())
             {
                 this.SetTemplatedParent(child, templatedParent);
             }

Perspex/Controls/ContentControl.cs

@@ -24,7 +24,7 @@ namespace Perspex.Controls
 
                 if (control != null)
                 {
-                    control.VisualParent = this;
+                    ((IVisual)control).VisualParent = this;
                     control.SetValue(ParentPropertyRW, this);
                 }
             });
@@ -38,7 +38,7 @@ namespace Perspex.Controls
 
         protected override Size ArrangeContent(Size finalSize)
         {
-            Control child = this.VisualChildren.SingleOrDefault() as Control;
+            Control child = ((IVisual)this).VisualChildren.SingleOrDefault() as Control;
 
             if (child != null)
             {
@@ -53,7 +53,7 @@ namespace Perspex.Controls
 
         protected override Size MeasureContent(Size availableSize)
         {
-            Control child = this.VisualChildren.SingleOrDefault() as Control;
+            Control child = ((IVisual)this).VisualChildren.SingleOrDefault() as Control;
 
             if (child != null)
             {

Perspex/Controls/ContentPresenter.cs

@@ -11,7 +11,7 @@ namespace Perspex.Controls
     using System.Linq;
     using Perspex.Media;
 
-    public class ContentPresenter : Control
+    public class ContentPresenter : Control, IVisual
     {
         public static readonly PerspexProperty<object> ContentProperty =
             ContentControl.ContentProperty.AddOwner<Control>();
@@ -33,7 +33,7 @@ namespace Perspex.Controls
             set { this.SetValue(DataTemplateProperty, value); }
         }
 
-        public override IEnumerable<IVisual> VisualChildren
+        IEnumerable<IVisual> IVisual.VisualChildren
         {
             get
             {
@@ -60,7 +60,7 @@ namespace Perspex.Controls
 
                     if (this.visualChild != null)
                     {
-                        this.visualChild.VisualParent = this;
+                        ((IVisual)this.visualChild).VisualParent = this;
                     }
                 }
 
@@ -70,7 +70,7 @@ namespace Perspex.Controls
 
         protected override Size ArrangeContent(Size finalSize)
         {
-            Control child = this.VisualChildren.SingleOrDefault() as Control;
+            Control child = ((IVisual)this).VisualChildren.SingleOrDefault() as Control;
 
             if (child != null)
             {
@@ -127,7 +127,7 @@ namespace Perspex.Controls
 
         protected override Size MeasureContent(Size availableSize)
         {
-            Control child = this.VisualChildren.SingleOrDefault() as Control;
+            Control child = ((IVisual)this).VisualChildren.SingleOrDefault() as Control;
 
             if (child != null)
             {

Perspex/Controls/Control.cs

@@ -192,7 +192,7 @@ namespace Perspex.Controls
                     throw new InvalidOperationException("ID already set.");
                 }
 
-                if (this.VisualParent != null)
+                if (((IVisual)this).VisualParent != null)
                 {
                     throw new InvalidOperationException("Cannot set ID : control already added to tree.");
                 }

Perspex/Controls/Decorator.cs

@@ -9,8 +9,9 @@ namespace Perspex.Controls
     using System;
     using System.Collections.Generic;
     using System.Linq;
+    using System.Reactive.Linq;
 
-    public abstract class Decorator : Control
+    public abstract class Decorator : Control, IVisual
     {
         public static readonly PerspexProperty<Control> ContentProperty =
             PerspexProperty.Register<ContentControl, Control>("Content");
@@ -21,7 +22,7 @@ namespace Perspex.Controls
         public Decorator()
         {
             // TODO: Unset old content's visual parent.
-            this.GetObservable(ContentProperty).Subscribe(x =>
+            this.GetObservable(ContentProperty).OfType<IVisual>().Subscribe(x =>
             {
                 if (x != null)
                 {
@@ -42,7 +43,7 @@ namespace Perspex.Controls
             set { this.SetValue(PaddingProperty, value); }
         }
 
-        public override IEnumerable<IVisual> VisualChildren
+        IEnumerable<IVisual> IVisual.VisualChildren
         {
             get 
             {

Perspex/Controls/TemplatedControl.cs

@@ -11,12 +11,12 @@ namespace Perspex.Controls
     using System.Linq;
     using Perspex.Media;
 
-    public abstract class TemplatedControl : Control, ITemplatedControl
+    public abstract class TemplatedControl : Control, IVisual, ITemplatedControl
     {
         public static readonly PerspexProperty<ControlTemplate> TemplateProperty =
             PerspexProperty.Register<TemplatedControl, ControlTemplate>("Template");
 
-        private Visual visualChild;
+        private IVisual visualChild;
 
         public ControlTemplate Template
         {
@@ -24,7 +24,7 @@ namespace Perspex.Controls
             set { this.SetValue(TemplateProperty, value); }
         }
 
-        public override IEnumerable<IVisual> VisualChildren
+        IEnumerable<IVisual> ITemplatedControl.VisualChildren
         {
             get 
             {
@@ -40,6 +40,11 @@ namespace Perspex.Controls
             }
         }
 
+        IEnumerable<IVisual> IVisual.VisualChildren
+        {
+            get { return ((ITemplatedControl)this).VisualChildren; }
+        }
+
         public sealed override void Render(IDrawingContext context)
         {
         }

Perspex/ILogical.cs

@@ -0,0 +1,21 @@
+// -----------------------------------------------------------------------
+// <copyright file="ILogical.cs" company="Steven Kirk">
+// Copyright 2014 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using System.Text;
+    using System.Threading.Tasks;
+
+    public interface ILogical
+    {
+        ILogical LogicalParent { get; set; }
+
+        IEnumerable<ILogical> LogicalChildren { get; }
+    }
+}

Perspex/IVisual.cs

@@ -15,8 +15,8 @@ namespace Perspex
         Rect Bounds { get; }
         
         IEnumerable<IVisual> VisualChildren { get; }
-        
-        IVisual VisualParent { get; }
+
+        IVisual VisualParent { get; set; }
 
         void Render(IDrawingContext context);
     }

Perspex/Perspex.csproj

@@ -79,6 +79,7 @@
     <Compile Include="Controls\ITemplatedControl.cs" />
     <Compile Include="Controls\TextBlock.cs" />
     <Compile Include="ControlTemplate.cs" />
+    <Compile Include="ILogical.cs" />
     <Compile Include="Input\MouseEventArgs.cs" />
     <Compile Include="Interactive.cs" />
     <Compile Include="IVisual.cs" />

Perspex/Properties/AssemblyInfo.cs

@@ -1,5 +1,6 @@
 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
@@ -26,3 +27,5 @@ using System.Resources;
 // [assembly: AssemblyVersion("1.0.*")]
 [assembly: AssemblyVersion("1.0.0.0")]
 [assembly: AssemblyFileVersion("1.0.0.0")]
+
+[assembly: InternalsVisibleTo("Perspex.UnitTests")]

Perspex/Visual.cs

@@ -12,8 +12,10 @@ namespace Perspex
     using System.Linq;
     using Perspex.Media;
 
-    public abstract class Visual : PerspexObject, IVisual
+    public abstract class Visual : PerspexObject, IVisual, ILogical
     {
+        private ILogical logicalParent;
+
         private IVisual visualParent;
 
         public Rect Bounds
@@ -22,19 +24,30 @@ namespace Perspex
             protected set;
         }
 
-        public virtual IEnumerable<IVisual> VisualChildren
+        ILogical ILogical.LogicalParent
+        {
+            get { return this.logicalParent; }
+            set { this.logicalParent = value; }
+        }
+
+        IEnumerable<ILogical> ILogical.LogicalChildren
+        {
+            get { return new ILogical[0]; }
+        }
+
+        IEnumerable<IVisual> IVisual.VisualChildren
         {
             get { return Enumerable.Empty<Visual>(); }
         }
 
-        public IVisual VisualParent
+        IVisual IVisual.VisualParent
         {
             get 
             { 
-                return this.visualParent; 
+                return this.visualParent;
             }
 
-            internal set
+            set
             {
                 if (this.visualParent != value)
                 {