Make border brush offset content

Perspex.Direct2D1.RenderTests/Controls/BorderTests.cs

@@ -73,5 +73,28 @@ namespace Perspex.Direct2D1.RenderTests.Controls
             this.RenderToFile(target);
             this.CompareImages();
         }
+
+        [TestMethod]
+        public void Border_Brush_Offsets_Content()
+        {
+            Decorator target = new Decorator
+            {
+                Padding = new Thickness(8),
+                Width = 200,
+                Height = 200,
+                Content = new Border
+                {
+                    BorderBrush = Brushes.Black,
+                    BorderThickness = 2,
+                    Content = new Border
+                    {
+                        Background = Brushes.Red,
+                    }
+                }
+            };
+
+            this.RenderToFile(target);
+            this.CompareImages();
+        }
     }
 }

Perspex/Controls/Border.cs

@@ -40,5 +40,23 @@ namespace Perspex.Controls
                 }
             }
         }
+
+        protected override Size ArrangeContent(Size finalSize)
+        {
+            Control content = this.Content;
+
+            if (content != null)
+            {
+                Thickness padding = this.Padding + new Thickness(this.BorderThickness);
+                content.Arrange(new Rect(finalSize).Deflate(padding));
+            }
+
+            return finalSize;
+        }
+
+        protected override Size MeasureContent(Size availableSize)
+        {
+            return this.DefaultMeasure(availableSize, this.Padding + new Thickness(this.BorderThickness));
+        }
     }
 }

Perspex/Controls/Decorator.cs

@@ -76,6 +76,11 @@ namespace Perspex.Controls
         }
 
         protected override Size MeasureContent(Size availableSize)
+        {
+            return this.DefaultMeasure(availableSize, this.Padding);
+        }
+
+        protected Size DefaultMeasure(Size availableSize, Thickness padding)
         {
             double width = 0;
             double height = 0;