Moved implementation to ChatRecentTextBox.cs and derived ChatTextBox.cs and StandAloneChatDisplay.cs from it.

osu.Game/Online/Chat/StandAloneChatDisplay.cs

@@ -12,7 +12,6 @@ using osu.Framework.Graphics.Shapes;
 using osu.Framework.Graphics.UserInterface;
 using osu.Framework.Input.Events;
 using osu.Game.Graphics;
-using osu.Game.Graphics.UserInterface;
 using osu.Game.Overlays.Chat;
 using osu.Game.Resources.Localisation.Web;
 using osuTK.Graphics;
@@ -120,18 +119,21 @@ namespace osu.Game.Online.Chat
             AddInternal(drawableChannel);
         }
 
-        public class ChatTextBox : FocusedTextBox
+        public class ChatTextBox : ChatRecentTextBox
         {
             protected override bool OnKeyDown(KeyDownEvent e)
             {
                 // Chat text boxes are generally used in places where they retain focus, but shouldn't block interaction with other
                 // elements on the same screen.
+                if (!HoldFocus)
+                {
                     switch (e.Key)
                     {
                         case Key.Up:
                         case Key.Down:
                             return false;
                     }
+                }
 
                 return base.OnKeyDown(e);
             }

osu.Game/Overlays/Chat/ChatRecentTextBox.cs

@@ -0,0 +1,74 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Collections.Generic;
+using osu.Framework.Input.Events;
+using osu.Game.Graphics.UserInterface;
+using osuTK.Input;
+
+namespace osu.Game.Overlays.Chat
+{
+    public class ChatRecentTextBox : FocusedTextBox
+    {
+        private readonly List<string> messageHistory = new List<string>();
+
+        private int messageIndex = -1;
+
+        private string originalMessage = string.Empty;
+
+        protected override bool OnKeyDown(KeyDownEvent e)
+        {
+            /* Behavior:
+             * add when on last element -> last element stays
+             * subtract when on first element -> sets to original text
+             * reset indexing when Text is set to Empty
+             */
+
+            switch (e.Key)
+            {
+                case Key.Up:
+                    if (messageIndex == -1)
+                        originalMessage = Text;
+
+                    if (messageIndex == messageHistory.Count - 1)
+                        return true;
+
+                    Text = messageHistory[++messageIndex];
+
+                    return true;
+
+                case Key.Down:
+                    if (messageIndex == -1)
+                        return true;
+
+                    if (messageIndex == 0)
+                    {
+                        messageIndex = -1;
+                        Text = originalMessage;
+                        return true;
+                    }
+
+                    Text = messageHistory[--messageIndex];
+
+                    return true;
+            }
+
+            bool onKeyDown = base.OnKeyDown(e);
+
+            if (string.IsNullOrEmpty(Text))
+                messageIndex = -1;
+
+            return onKeyDown;
+        }
+
+        protected override void Commit()
+        {
+            if (!string.IsNullOrEmpty(Text))
+                messageHistory.Insert(0, Text);
+
+            messageIndex = -1;
+
+            base.Commit();
+        }
+    }
+}

osu.Game/Overlays/Chat/ChatTextBox.cs

@@ -1,23 +1,13 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-using System.Collections.Generic;
 using osu.Framework.Bindables;
-using osu.Framework.Input.Events;
-using osu.Game.Graphics.UserInterface;
 using osu.Game.Resources.Localisation.Web;
-using osuTK.Input;
 
 namespace osu.Game.Overlays.Chat
 {
-    public class ChatTextBox : FocusedTextBox
+    public class ChatTextBox : ChatRecentTextBox
     {
-        private readonly List<string> messageHistory = new List<string>();
-
-        private int messageIndex = -1;
-
-        private string originalMessage = string.Empty;
-
         public readonly BindableBool ShowSearch = new BindableBool();
 
         public override bool HandleLeftRightArrows => !ShowSearch.Value;
@@ -37,59 +27,11 @@ namespace osu.Game.Overlays.Chat
             }, true);
         }
 
-        protected override bool OnKeyDown(KeyDownEvent e)
-        {
-            /* Behavior:
-             * add when on last element -> last element stays
-             * subtract when on first element -> sets to original text
-             * reset indexing when Text is set to Empty
-             */
-
-            switch (e.Key)
-            {
-                case Key.Up:
-                    if (messageIndex == -1)
-                        originalMessage = Text;
-
-                    if (messageIndex == messageHistory.Count - 1)
-                        return true;
-
-                    Text = messageHistory[++messageIndex];
-
-                    return true;
-
-                case Key.Down:
-                    if (messageIndex == -1)
-                        return true;
-
-                    if (messageIndex == 0)
-                    {
-                        messageIndex = -1;
-                        Text = originalMessage;
-                        return true;
-                    }
-
-                    Text = messageHistory[--messageIndex];
-
-                    return true;
-            }
-
-            bool onKeyDown = base.OnKeyDown(e);
-
-            if (string.IsNullOrEmpty(Text))
-                messageIndex = -1;
-
-            return onKeyDown;
-        }
-
         protected override void Commit()
         {
             if (ShowSearch.Value)
                 return;
 
-            messageHistory.Insert(0, Text);
-            messageIndex = -1;
-
             base.Commit();
         }
     }