Don't think bounds needs to be a PP.

Perspex/IStyle.cs

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

Perspex/Perspex.csproj

@@ -77,6 +77,7 @@
     <Compile Include="Controls\Control.cs" />
     <Compile Include="Controls\TextBlock.cs" />
     <Compile Include="IBindingDescription.cs" />
+    <Compile Include="IStyle.cs" />
     <Compile Include="Layout\ILayoutable.cs" />
     <Compile Include="Layout\ILayoutManager.cs" />
     <Compile Include="Layout\ILayoutRoot.cs" />
@@ -104,6 +105,8 @@
     <Compile Include="Controls\TemplatedControl.cs" />
     <Compile Include="Style.cs" />
     <Compile Include="Styles.cs" />
+    <Compile Include="Themes\Default\ButtonStyle.cs" />
+    <Compile Include="Themes\Default\DefaultTheme.cs" />
     <Compile Include="Thickness.cs" />
     <Compile Include="Visual.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />

Perspex/PerspexList.cs

@@ -26,5 +26,13 @@
             get;
             private set;
         }
+
+        public void AddRange(IEnumerable<T> items)
+        {
+            foreach (T item in items)
+            {
+                this.Add(item);
+            }
+        }
     }
 }

Perspex/Style.cs

@@ -13,7 +13,7 @@ namespace Perspex
     using System.Reactive.Subjects;
     using Perspex.Controls;
 
-    public class Style
+    public class Style : IStyle
     {
         public Style()
         {

Perspex/Styles.cs

@@ -8,11 +8,11 @@ namespace Perspex
 {
     using Perspex.Controls;
 
-    public class Styles : PerspexList<Style>
+    public class Styles : PerspexList<IStyle>, IStyle
     {
         public void Attach(Control control)
         {
-            foreach (Style style in this)
+            foreach (IStyle style in this)
             {
                 style.Attach(control);
             }

Perspex/Themes/Default/ButtonStyle.cs

@@ -0,0 +1,38 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Perspex.Controls;
+using Perspex.Media;
+
+namespace Perspex.Themes.Default
+{
+    public class ButtonStyle : Styles
+    {
+        public ButtonStyle()
+        {
+            this.AddRange(new[]
+            {
+                new Style(x => x.Select<Button>())
+                {
+                    Setters = new[]
+                    {
+                        new Setter(Button.BackgroundProperty, new SolidColorBrush(0xffdddddd)),
+                        new Setter(Button.BorderBrushProperty, new SolidColorBrush(0xff707070)),
+                        new Setter(Button.BorderThicknessProperty, 2.0),
+                        new Setter(Button.ForegroundProperty, new SolidColorBrush(0xff000000)),
+                    },
+                },
+                new Style(x => x.Select<Button>().Class(":mouseover"))
+                {
+                    Setters = new[]
+                    {
+                        new Setter (Button.BackgroundProperty, new SolidColorBrush(0xffbee6fd)),
+                        new Setter (Button.BorderBrushProperty, new SolidColorBrush(0xff3c7fb1)),
+                    },
+                }
+            });
+        }
+    }
+}

Perspex/Themes/Default/DefaultTheme.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Perspex.Themes.Default
+{
+    public class DefaultTheme : Styles
+    {
+        public DefaultTheme()
+        {
+            this.Add(new ButtonStyle());
+        }
+    }
+}

Perspex/Visual.cs

@@ -14,18 +14,12 @@ namespace Perspex
 
     public abstract class Visual : PerspexObject
     {
-        public static readonly ReadOnlyPerspexProperty<Rect> BoundsProperty =
-            new ReadOnlyPerspexProperty<Rect>(BoundsPropertyRW);
-
-        private static readonly PerspexProperty<Rect> BoundsPropertyRW =
-            PerspexProperty.Register<Visual, Rect>("Bounds");
-
         private Visual visualParent;
 
         public Rect Bounds
         {
-            get { return this.GetValue(BoundsPropertyRW); }
+            get;
-            protected set { this.SetValue(BoundsPropertyRW, value); }
+            protected set;
         }
 
         public virtual IEnumerable<Visual> VisualChildren

TestApplication/Program.cs

@@ -8,6 +8,7 @@ using System.Threading.Tasks;
 using Perspex;
 using Perspex.Controls;
 using Perspex.Media;
+using Perspex.Themes.Default;
 using Perspex.Windows;
 using Perspex.Windows.Media;
 using Perspex.Windows.Threading;
@@ -42,24 +43,7 @@ namespace TestApplication
             {
                 Styles = new Styles 
                 {
-                    new Style(x => x.Select<Button>())
+                    new DefaultTheme(),
-                    {
-                        Setters = new[]
-                        {
-                            new Setter(Button.BackgroundProperty, new SolidColorBrush(0xffdddddd)),
-                            new Setter(Button.BorderBrushProperty, new SolidColorBrush(0xff707070)),
-                            new Setter(Button.BorderThicknessProperty, 2.0),
-                            new Setter(Button.ForegroundProperty, new SolidColorBrush(0xff000000)),
-                        },
-                    },
-                    new Style(x => x.Select<Button>().Class(":mouseover"))
-                    {
-                        Setters = new[]
-                        {
-                            new Setter (Button.BackgroundProperty, new SolidColorBrush(0xffbee6fd)),
-                            new Setter (Button.BorderBrushProperty, new SolidColorBrush(0xff3c7fb1)),
-                        },
-                    }
                 }
             };