Improve feel of settings toolbox group

osu.Game.Tests/Visual/UserInterface/TestSceneSettingsToolboxGroup.cs

@@ -5,12 +5,14 @@
 
 using System.Linq;
 using NUnit.Framework;
+using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Testing;
 using osu.Game.Graphics.UserInterface;
 using osu.Game.Graphics.UserInterfaceV2;
 using osu.Game.Overlays;
 using osu.Game.Overlays.Settings;
+using osuTK;
 using osuTK.Input;
 
 namespace osu.Game.Tests.Visual.UserInterface
@@ -20,11 +22,17 @@ namespace osu.Game.Tests.Visual.UserInterface
     {
         private SettingsToolboxGroup group;
 
+        [Cached]
+        private OverlayColourProvider colourProvider = new OverlayColourProvider(OverlayColourScheme.Blue);
+
         [SetUp]
         public void SetUp() => Schedule(() =>
         {
             Child = group = new SettingsToolboxGroup("example")
             {
+                Scale = new Vector2(3),
+                Anchor = Anchor.Centre,
+                Origin = Anchor.Centre,
                 Children = new Drawable[]
                 {
                     new RoundedButton

osu.Game/Overlays/SettingsToolboxGroup.cs

@@ -1,8 +1,7 @@
 // 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.
 
-#nullable disable
-
+using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Caching;
 using osu.Framework.Extensions.EnumExtensions;
@@ -23,25 +22,40 @@ namespace osu.Game.Overlays
 {
     public class SettingsToolboxGroup : Container, IExpandable
     {
+        private readonly string title;
         public const int CONTAINER_WIDTH = 270;
 
         private const float transition_duration = 250;
-        private const int border_thickness = 2;
         private const int header_height = 30;
         private const int corner_radius = 5;
 
-        private const float fade_duration = 800;
-        private const float inactive_alpha = 0.5f;
-
         private readonly Cached headerTextVisibilityCache = new Cached();
 
-        private readonly FillFlowContainer content;
+        protected override Container<Drawable> Content => content;
+
+        private readonly FillFlowContainer content = new FillFlowContainer
+        {
+            Name = @"Content",
+            Origin = Anchor.TopCentre,
+            Anchor = Anchor.TopCentre,
+            Direction = FillDirection.Vertical,
+            RelativeSizeAxes = Axes.X,
+            AutoSizeDuration = transition_duration,
+            AutoSizeEasing = Easing.OutQuint,
+            AutoSizeAxes = Axes.Y,
+            Padding = new MarginPadding { Horizontal = 10, Top = 5, Bottom = 10 },
+            Spacing = new Vector2(0, 15),
+        };
 
         public BindableBool Expanded { get; } = new BindableBool(true);
 
-        private readonly OsuSpriteText headerText;
+        private OsuSpriteText headerText = null!;
 
-        private readonly Container headerContent;
+        private Container headerContent = null!;
+
+        private Box background = null!;
+
+        private IconButton expandButton = null!;
 
         /// <summary>
         /// Create a new instance.
@@ -49,20 +63,24 @@ namespace osu.Game.Overlays
         /// <param name="title">The title to be displayed in the header of this group.</param>
         public SettingsToolboxGroup(string title)
         {
+            this.title = title;
+
             AutoSizeAxes = Axes.Y;
             Width = CONTAINER_WIDTH;
             Masking = true;
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(OverlayColourProvider colourProvider)
+        {
             CornerRadius = corner_radius;
-            BorderColour = Color4.Black;
-            BorderThickness = border_thickness;
 
             InternalChildren = new Drawable[]
             {
-                new Box
+                background = new Box
                 {
                     RelativeSizeAxes = Axes.Both,
-                    Colour = Color4.Black,
-                    Alpha = 0.5f,
+                    Colour = colourProvider.Background5,
                 },
                 new FillFlowContainer
                 {
@@ -88,7 +106,7 @@ namespace osu.Game.Overlays
                                     Font = OsuFont.GetFont(weight: FontWeight.Bold, size: 17),
                                     Padding = new MarginPadding { Left = 10, Right = 30 },
                                 },
-                                new IconButton
+                                expandButton = new IconButton
                                 {
                                     Origin = Anchor.Centre,
                                     Anchor = Anchor.CentreRight,
@@ -99,19 +117,7 @@ namespace osu.Game.Overlays
                                 },
                             }
                         },
-                        content = new FillFlowContainer
-                        {
-                            Name = @"Content",
-                            Origin = Anchor.TopCentre,
-                            Anchor = Anchor.TopCentre,
-                            Direction = FillDirection.Vertical,
-                            RelativeSizeAxes = Axes.X,
-                            AutoSizeDuration = transition_duration,
-                            AutoSizeEasing = Easing.OutQuint,
-                            AutoSizeAxes = Axes.Y,
-                            Padding = new MarginPadding(15),
-                            Spacing = new Vector2(0, 15),
-                        }
+                        content
                     }
                 },
             };
@@ -175,9 +181,10 @@ namespace osu.Game.Overlays
 
         private void updateFadeState()
         {
-            this.FadeTo(IsHovered ? 1 : inactive_alpha, fade_duration, Easing.OutQuint);
-        }
+            const float fade_duration = 500;
 
-        protected override Container<Drawable> Content => content;
+            background.FadeTo(IsHovered ? 1 : 0, fade_duration, Easing.OutQuint);
+            expandButton.FadeTo(IsHovered ? 1 : 0, fade_duration, Easing.OutQuint);
+        }
     }
 }

osu.Game/Screens/Play/PlayerLoader.cs

@@ -71,6 +71,9 @@ namespace osu.Game.Screens.Play
         private AudioFilter lowPassFilter = null!;
         private AudioFilter highPassFilter = null!;
 
+        [Cached]
+        private OverlayColourProvider colourProvider = new OverlayColourProvider(OverlayColourScheme.Purple);
+
         protected bool BackgroundBrightnessReduction
         {
             set