From a297f0086304e6c47b44655fb7cdd14420e84657 Mon Sep 17 00:00:00 2001
From: Andrey Kunchev <donandren@gmail.com>
Date: Tue, 20 Nov 2018 01:02:36 +0200
Subject: [PATCH] Scroll and focus to selected item when dropdown is shown

---
 src/Avalonia.Controls/DropDown.cs     |  8 +++++++
 src/Avalonia.Controls/DropDownItem.cs | 32 ++++-----------------------
 2 files changed, 12 insertions(+), 28 deletions(-)

diff --git a/src/Avalonia.Controls/DropDown.cs b/src/Avalonia.Controls/DropDown.cs
index 4ac2b6f822..a30cc231b7 100644
--- a/src/Avalonia.Controls/DropDown.cs
+++ b/src/Avalonia.Controls/DropDown.cs
@@ -190,6 +190,14 @@ namespace Avalonia.Controls
             base.OnTemplateApplied(e);
         }
 
+        internal void ItemFocused(DropDownItem dropDownItem)
+        {
+            if (IsDropDownOpen && dropDownItem.IsFocused && dropDownItem.IsArrangeValid)
+            {
+                dropDownItem.BringIntoView();
+            }
+        }
+
         private void PopupClosed(object sender, EventArgs e)
         {
             if (Focusable)
diff --git a/src/Avalonia.Controls/DropDownItem.cs b/src/Avalonia.Controls/DropDownItem.cs
index fb465e93ec..1e22ededf6 100644
--- a/src/Avalonia.Controls/DropDownItem.cs
+++ b/src/Avalonia.Controls/DropDownItem.cs
@@ -2,43 +2,19 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using System;
+using System.Reactive.Linq;
 
 namespace Avalonia.Controls
 {
     /// <summary>
     /// A selectable item in a <see cref="DropDown"/>.
     /// </summary>
-    public class DropDownItem : ContentControl, ISelectable
+    public class DropDownItem : ListBoxItem
     {
-        /// <summary>
-        /// Defines the <see cref="IsSelected"/> property.
-        /// </summary>
-        public static readonly StyledProperty<bool> IsSelectedProperty =
-            AvaloniaProperty.Register<DropDownItem, bool>(nameof(IsSelected));
-
-        /// <summary>
-        /// Initializes static members of the <see cref="DropDownItem"/> class.
-        /// </summary>
-        static DropDownItem()
-        {
-            FocusableProperty.OverrideDefaultValue<DropDownItem>(true);
-        }
-
         public DropDownItem()
         {
-            this.GetObservable(DropDownItem.IsFocusedProperty).Subscribe(focused =>
-            {
-                PseudoClasses.Set(":selected", focused);                
-            });
-        }
-
-        /// <summary>
-        /// Gets or sets the selection state of the item.
-        /// </summary>
-        public bool IsSelected
-        {
-            get { return GetValue(IsSelectedProperty); }
-            set { SetValue(IsSelectedProperty, value); }
+            this.GetObservable(DropDownItem.IsFocusedProperty).Where(focused => focused)
+                .Subscribe(_ => (Parent as DropDown)?.ItemFocused(this));
         }
     }
 }