Put button style into its own file.

And add StyleInclude class to import it. Unfortunately doesn't work yet
due to bug in OmniXAML: https://github.com/SuperJMN/OmniXAML/issues/48

samples/XamlTestApplicationPcl/Button.paml

@@ -0,0 +1,33 @@
+<Styles xmlns="https://github.com/perspex">
+  <Style Selector="Button">
+    <Setter Property="Background" Value="#ffaaaaaa"/>
+    <Setter Property="BorderBrush" Value="#ffaaaaaa"/>
+    <Setter Property="BorderThickness" Value="2"/>
+    <Setter Property="Foreground" Value="Black"/>
+    <Setter Property="HorizontalContentAlignment" Value="Center"/>
+    <Setter Property="VerticalContentAlignment" Value="Center"/>
+    <Setter Property="Template">
+      <ControlTemplate TargetType="Button">
+        <Border Name="border"
+                Padding="3"
+                Background="{TemplateBinding Background}"
+                BorderBrush="{TemplateBinding BorderBrush}"
+                BorderThickness="{TemplateBinding BorderThickness}">
+          <ContentPresenter Content="{TemplateBinding Content}"
+                            TextBlock.Foreground="{TemplateBinding Foreground}"
+                            HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
+                            VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
+        </Border>
+      </ControlTemplate>
+    </Setter>
+  </Style>
+  <Style Selector="Button:pointerover /template/ Border#border">
+    <Setter Property="BorderBrush" Value="#ff888888"/>
+  </Style>
+  <Style Selector="Button:pressed  /template/ Border#border">
+    <Setter Property="Background" Value="#ff888888"/>
+  </Style>
+  <Style Selector="Button:disabled">
+    <Setter Property="Opacity" Value="0.5"/>
+  </Style>
+</Styles>

samples/XamlTestApplicationPcl/XamlTestApp.paml

@@ -2,36 +2,6 @@
         xmlns="https://github.com/perspex"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
   <Application.Styles>
-    <Style Selector="Button">
-      <Setter Property="Background" Value="#ffaaaaaa"/>
-      <Setter Property="BorderBrush" Value="#ffaaaaaa"/>
-      <Setter Property="BorderThickness" Value="2"/>
-      <Setter Property="Foreground" Value="Black"/>
-      <Setter Property="HorizontalContentAlignment" Value="Center"/>
-      <Setter Property="VerticalContentAlignment" Value="Center"/>
-      <Setter Property="Template">
-        <ControlTemplate TargetType="Button">
-          <Border Name="border"
-                  Padding="3"
-                  Background="{TemplateBinding Background}"
-                  BorderBrush="{TemplateBinding BorderBrush}"
-                  BorderThickness="{TemplateBinding BorderThickness}">
-            <ContentPresenter Content="{TemplateBinding Content}"
-                              TextBlock.Foreground="{TemplateBinding Foreground}"
-                              HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
-                              VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
-          </Border>
-        </ControlTemplate>
-      </Setter>
-    </Style>
-    <Style Selector="Button:pointerover /template/ Border#border">
-      <Setter Property="BorderBrush" Value="#ff888888"/>
-    </Style>
-    <Style Selector="Button:pressed  /template/ Border#border">
-      <Setter Property="Background" Value="#ff888888"/>
-    </Style>
-    <Style Selector="Button:disabled">
-      <Setter Property="Opacity" Value="0.5"/>
-    </Style>
+    <StyleInclude Source="resource://application/XamlTestApplicationPcl/XamlTestApplication.Button.paml"/>
   </Application.Styles>
 </Application>

samples/XamlTestApplicationPcl/XamlTestApplicationPcl.csproj

@@ -121,6 +121,9 @@
       <SubType>Designer</SubType>
     </EmbeddedResource>
     <None Include="packages.config" />
+    <EmbeddedResource Include="Button.paml">
+      <SubType>Designer</SubType>
+    </EmbeddedResource>
   </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. 

src/Markup/Perspex.Markup.Xaml/Context/PerspexWiringContext.cs

@@ -95,14 +95,15 @@ namespace Perspex.Markup.Xaml.Context
                 new TypeConverterRegistration(typeof(Classes), new ClassesTypeConverter()),
                 new TypeConverterRegistration(typeof(ColumnDefinitions), new ColumnDefinitionsTypeConverter()),
                 new TypeConverterRegistration(typeof(GridLength), new GridLengthTypeConverter()),
+                new TypeConverterRegistration(typeof(KeyGesture), new KeyGestureConverter()),
                 new TypeConverterRegistration(typeof(Point), new PointTypeConverter()),
                 new TypeConverterRegistration(typeof(PerspexProperty), new PerspexPropertyTypeConverter()),
                 new TypeConverterRegistration(typeof(RelativePoint), new RelativePointTypeConverter()),
                 new TypeConverterRegistration(typeof(RowDefinitions), new RowDefinitionsTypeConverter()),
-                new TypeConverterRegistration(typeof(Thickness), new ThicknessTypeConverter()),
                 new TypeConverterRegistration(typeof(Selector), new SelectorTypeConverter()),
+                new TypeConverterRegistration(typeof(Thickness), new ThicknessTypeConverter()),
                 new TypeConverterRegistration(typeof(TimeSpan), new TimeSpanTypeConverter()),
-                new TypeConverterRegistration(typeof(KeyGesture), new KeyGestureConverter())
+                new TypeConverterRegistration(typeof(Uri), new UriTypeConverter()),
             };
 
             typeConverterProvider.AddAll(converters);

src/Markup/Perspex.Markup.Xaml/Converters/UriTypeConverter.cs

@@ -0,0 +1,32 @@
+// Copyright (c) The Perspex Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
+using System.Globalization;
+using OmniXaml.TypeConversion;
+
+namespace Perspex.Markup.Xaml.Converters
+{
+    public class UriTypeConverter : ITypeConverter
+    {
+        public bool CanConvertFrom(IXamlTypeConverterContext context, Type sourceType)
+        {
+            return sourceType == typeof(string);
+        }
+
+        public bool CanConvertTo(IXamlTypeConverterContext context, Type destinationType)
+        {
+            return false;
+        }
+
+        public object ConvertFrom(IXamlTypeConverterContext context, CultureInfo culture, object value)
+        {
+            return new Uri((string)value);
+        }
+
+        public object ConvertTo(IXamlTypeConverterContext context, CultureInfo culture, object value, Type destinationType)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

src/Markup/Perspex.Markup.Xaml/Perspex.Markup.Xaml.csproj

@@ -51,6 +51,7 @@
     <Compile Include="Converters\ClassesTypeConverter.cs" />
     <Compile Include="Converters\RowDefinitionsTypeConverter.cs" />
     <Compile Include="Converters\ColumnDefinitionsTypeConverter.cs" />
+    <Compile Include="Converters\UriTypeConverter.cs" />
     <Compile Include="Converters\ThicknessTypeConverter.cs" />
     <Compile Include="Converters\PerspexPropertyTypeConverter.cs" />
     <Compile Include="Converters\SelectorTypeConverter.cs" />
@@ -231,6 +232,7 @@
     <Compile Include="Parsers\SelectorParser.cs" />
     <Compile Include="Parsers\SelectorGrammar.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="Styling\StyleInclude.cs" />
     <Compile Include="Templates\ControlTemplate.cs" />
     <Compile Include="Templates\TemplateLoader.cs" />
     <Compile Include="Templates\Template.cs" />

src/Markup/Perspex.Markup.Xaml/PerspexXamlLoader.cs

@@ -108,7 +108,7 @@ namespace Perspex.Markup.Xaml
         {
             var asm = type.GetTypeInfo().Assembly.GetName().Name;
             var typeName = type.FullName;
-            yield return new Uri("resource://application/" + asm + "/" + typeName+".xaml");
+            yield return new Uri("resource://application/" + asm + "/" + typeName + ".xaml");
             yield return new Uri("resource://application/" + asm + "/" + typeName + ".paml");
 
         }

src/Markup/Perspex.Markup.Xaml/Properties/AssemblyInfo.cs

@@ -7,6 +7,7 @@ using System.Runtime.CompilerServices;
 
 [assembly: AssemblyTitle("Perspex.Markup.Xaml")]
 [assembly: XmlnsDefinition("https://github.com/perspex", "Perspex.Markup.Xaml.MarkupExtensions")]
+[assembly: XmlnsDefinition("https://github.com/perspex", "Perspex.Markup.Xaml.Styling")]
 [assembly: XmlnsDefinition("https://github.com/perspex", "Perspex.Markup.Xaml.Templates")]
 [assembly: InternalsVisibleTo("Perspex.Markup.Xaml.UnitTests")]
 

src/Markup/Perspex.Markup.Xaml/Styling/StyleInclude.cs

@@ -0,0 +1,39 @@
+// Copyright (c) The Perspex Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
+using Perspex.Styling;
+
+namespace Perspex.Markup.Xaml.Styling
+{
+    /// <summary>
+    /// Includes a style from a URL.
+    /// </summary>
+    public class StyleInclude : IStyle
+    {
+        /// <summary>
+        /// Gets or sets the source URL.
+        /// </summary>
+        public Uri Source { get; set; }
+
+        /// <summary>
+        /// Gets the loaded style.
+        /// </summary>
+        public IStyle Loaded { get; private set; }
+
+        /// <inheritdoc/>
+        public void Attach(IStyleable control, IStyleHost container)
+        {
+            if (Source != null)
+            {
+                if (Loaded == null)
+                {
+                    var loader = new PerspexXamlLoader();
+                    Loaded = (IStyle)loader.Load(Source);
+                }
+
+                Loaded.Attach(control, container);
+            }
+        }
+    }
+}