From 1bbc155303dbcdaffec3d8f36356e2467ba9fd99 Mon Sep 17 00:00:00 2001
From: Jeremy Koritzinsky <jkoritzinsky@gmail.com>
Date: Tue, 29 May 2018 15:35:08 -0500
Subject: [PATCH] Use a concrete type for the host type to avoid #959.

---
 src/Avalonia.Controls/Design.cs                    | 6 +++---
 src/Avalonia.DesignerSupport/DesignWindowLoader.cs | 3 +--
 src/Avalonia.Styling/Styling/IStyle.cs             | 2 +-
 3 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/src/Avalonia.Controls/Design.cs b/src/Avalonia.Controls/Design.cs
index 3a67e554ac..894240a09f 100644
--- a/src/Avalonia.Controls/Design.cs
+++ b/src/Avalonia.Controls/Design.cs
@@ -48,14 +48,14 @@ namespace Avalonia.Controls
         }
         
         public static readonly AttachedProperty<Control> PreviewWithProperty = AvaloniaProperty
-            .RegisterAttached<IStyle, Control>("PreviewWith", typeof (Design));
+            .RegisterAttached<Style, Control>("PreviewWith", typeof (Design));
 
-        public static void SetPreviewWith(IStyle target, Control control)
+        public static void SetPreviewWith(Style target, Control control)
         {
             target.SetValue(PreviewWithProperty, control);
         }
 
-        public static Control GetPreviewWith(IStyle target)
+        public static Control GetPreviewWith(Style target)
         {
             return target.GetValue(PreviewWithProperty);
         }
diff --git a/src/Avalonia.DesignerSupport/DesignWindowLoader.cs b/src/Avalonia.DesignerSupport/DesignWindowLoader.cs
index d1958ac9bf..6dca479d38 100644
--- a/src/Avalonia.DesignerSupport/DesignWindowLoader.cs
+++ b/src/Avalonia.DesignerSupport/DesignWindowLoader.cs
@@ -36,8 +36,7 @@ namespace Avalonia.DesignerSupport
                 var styles = loaded as Styles;
                 if (styles != null)
                 {
-                    var substitute = Design.GetPreviewWith(styles) ??
-                                     styles.Select(Design.GetPreviewWith).FirstOrDefault(s => s != null);
+                    var substitute = styles.OfType<Style>().Select(Design.GetPreviewWith).FirstOrDefault(s => s != null);
                     if (substitute != null)
                     {
                         substitute.Styles.AddRange(styles);
diff --git a/src/Avalonia.Styling/Styling/IStyle.cs b/src/Avalonia.Styling/Styling/IStyle.cs
index 2ce06cc36c..5f12763825 100644
--- a/src/Avalonia.Styling/Styling/IStyle.cs
+++ b/src/Avalonia.Styling/Styling/IStyle.cs
@@ -8,7 +8,7 @@ namespace Avalonia.Styling
     /// <summary>
     /// Defines the interface for styles.
     /// </summary>
-    public interface IStyle : IAvaloniaObject, IResourceNode
+    public interface IStyle : IResourceNode
     {
         /// <summary>
         /// Attaches the style to a control if the style's selector matches.