Flash footer freemod/freestyle buttons when active

osu.Game/Screens/OnlinePlay/FooterButtonFreeMods.cs

@@ -26,6 +26,8 @@ namespace osu.Game.Screens.OnlinePlay
         public readonly Bindable<IReadOnlyList<Mod>> FreeMods = new Bindable<IReadOnlyList<Mod>>();
         public readonly IBindable<bool> Freestyle = new Bindable<bool>();
 
+        protected override bool IsActive => FreeMods.Value.Count > 0;
+
         public new Action Action { set => throw new NotSupportedException("The click action is handled by the button itself."); }
 
         private OsuSpriteText count = null!;

osu.Game/Screens/OnlinePlay/FooterButtonFreestyle.cs

@@ -8,11 +8,10 @@ using osu.Framework.Extensions.Color4Extensions;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Shapes;
-using osu.Framework.Graphics.UserInterface;
 using osu.Game.Graphics;
 using osu.Game.Graphics.Sprites;
-using osu.Game.Screens.Select;
 using osu.Game.Localisation;
+using osu.Game.Screens.Select;
 
 namespace osu.Game.Screens.OnlinePlay
 {
@@ -20,6 +19,7 @@ namespace osu.Game.Screens.OnlinePlay
     {
         public readonly Bindable<bool> Freestyle = new Bindable<bool>();
 
+        protected override bool IsActive => Freestyle.Value;
 
         public new Action Action { set => throw new NotSupportedException("The click action is handled by the button itself."); }
 

osu.Game/Screens/OnlinePlay/OnlinePlaySongSelect.cs

@@ -42,7 +42,7 @@ namespace osu.Game.Screens.OnlinePlay
         protected override UserActivity InitialActivity => new UserActivity.InLobby(room);
 
         protected readonly Bindable<IReadOnlyList<Mod>> FreeMods = new Bindable<IReadOnlyList<Mod>>(Array.Empty<Mod>());
-        protected readonly Bindable<bool> Freestyle = new Bindable<bool>();
+        protected readonly Bindable<bool> Freestyle = new Bindable<bool>(true);
 
         private readonly Room room;
         private readonly PlaylistItem? initialItem;

osu.Game/Screens/Select/FooterButton.cs

@@ -25,6 +25,11 @@ namespace osu.Game.Screens.Select
 
         protected static readonly Vector2 SHEAR = new Vector2(SHEAR_WIDTH / Footer.HEIGHT, 0);
 
+        /// <summary>
+        /// Used to show an initial animation hinting at the enabled state.
+        /// </summary>
+        protected virtual bool IsActive => false;
+
         public LocalisableString Text
         {
             get => SpriteText?.Text ?? default;
@@ -124,6 +129,18 @@ namespace osu.Game.Screens.Select
         {
             base.LoadComplete();
             Enabled.BindValueChanged(_ => updateDisplay(), true);
+
+            if (IsActive)
+            {
+                box.ClearTransforms();
+
+                using (box.BeginDelayedSequence(200))
+                {
+                    box.FadeIn(200)
+                       .Then()
+                       .FadeOut(1500, Easing.OutQuint);
+                }
+            }
         }
 
         public Action Hovered;