Disable button instead of hiding (and add tooltip)

osu.Game/Graphics/UserInterfaceV2/FormColourPalette.cs

@@ -100,7 +100,19 @@ namespace osu.Game.Graphics.UserInterfaceV2
                 if (args.Action != NotifyCollectionChangedAction.Replace)
                     updateColours();
             }, true);
-            CanAdd.BindValueChanged(_ => addButton.Alpha = CanAdd.Value ? 1 : 0, true);
+            CanAdd.BindValueChanged(canAdd =>
+            {
+                if (canAdd.NewValue)
+                {
+                    addButton.Enabled.Value = true;
+                    addButton.TooltipText = string.Empty;
+                }
+                else
+                {
+                    addButton.Enabled.Value = false;
+                    addButton.TooltipText = "Maximum combo colours reached";
+                }
+            }, true);
             updateState();
         }
 

osu.Game/Graphics/UserInterfaceV2/RoundedButton.cs

@@ -8,6 +8,7 @@ using osu.Framework.Extensions.Color4Extensions;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Colour;
 using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Cursor;
 using osu.Framework.Input.Events;
 using osu.Framework.Localisation;
 using osu.Game.Graphics.Backgrounds;
@@ -17,7 +18,7 @@ using osuTK.Graphics;
 
 namespace osu.Game.Graphics.UserInterfaceV2
 {
-    public partial class RoundedButton : OsuButton, IFilterable
+    public partial class RoundedButton : OsuButton, IFilterable, IHasTooltip
     {
         protected TrianglesV2? Triangles { get; private set; }
 
@@ -107,5 +108,7 @@ namespace osu.Game.Graphics.UserInterfaceV2
         }
 
         public bool FilteringActive { get; set; }
+
+        public virtual LocalisableString TooltipText { get; set; }
     }
 }

osu.Game/Overlays/BeatmapSet/Buttons/FavouriteButton.cs

@@ -7,7 +7,6 @@ using System.Diagnostics;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
-using osu.Framework.Graphics.Cursor;
 using osu.Framework.Graphics.Sprites;
 using osu.Framework.Localisation;
 using osu.Game.Graphics.UserInterface;
@@ -21,7 +20,7 @@ using APIUser = osu.Game.Online.API.Requests.Responses.APIUser;
 
 namespace osu.Game.Overlays.BeatmapSet.Buttons
 {
-    public partial class FavouriteButton : HeaderButton, IHasTooltip
+    public partial class FavouriteButton : HeaderButton
     {
         public readonly Bindable<APIBeatmapSet> BeatmapSet = new Bindable<APIBeatmapSet>();
 
@@ -32,7 +31,7 @@ namespace osu.Game.Overlays.BeatmapSet.Buttons
 
         private readonly IBindable<APIUser> localUser = new Bindable<APIUser>();
 
-        public LocalisableString TooltipText
+        public override LocalisableString TooltipText
         {
             get
             {

osu.Game/Overlays/Settings/SettingsButton.cs

@@ -6,13 +6,12 @@ using System.Collections.Generic;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
-using osu.Framework.Graphics.Cursor;
 using osu.Framework.Localisation;
 using osu.Game.Graphics.UserInterfaceV2;
 
 namespace osu.Game.Overlays.Settings
 {
-    public partial class SettingsButton : RoundedButton, IHasTooltip, IConditionalFilterable
+    public partial class SettingsButton : RoundedButton, IConditionalFilterable
     {
         public SettingsButton()
         {
@@ -25,8 +24,6 @@ namespace osu.Game.Overlays.Settings
         public BindableBool CanBeShown { get; } = new BindableBool(true);
         IBindable<bool> IConditionalFilterable.CanBeShown => CanBeShown;
 
-        public LocalisableString TooltipText { get; set; }
-
         public override IEnumerable<LocalisableString> FilterTerms
         {
             get

osu.Game/Screens/OnlinePlay/Components/ReadyButton.cs

@@ -3,7 +3,6 @@
 
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
-using osu.Framework.Graphics.Cursor;
 using osu.Framework.Localisation;
 using osu.Game.Graphics.UserInterfaceV2;
 using osu.Game.Online;
@@ -11,7 +10,7 @@ using osu.Game.Online.Rooms;
 
 namespace osu.Game.Screens.OnlinePlay.Components
 {
-    public abstract partial class ReadyButton : RoundedButton, IHasTooltip
+    public abstract partial class ReadyButton : RoundedButton
     {
         public new readonly BindableBool Enabled = new BindableBool();
 
@@ -29,7 +28,7 @@ namespace osu.Game.Screens.OnlinePlay.Components
         private void updateState() =>
             base.Enabled.Value = availability.Value.State == DownloadState.LocallyAvailable && Enabled.Value;
 
-        public virtual LocalisableString TooltipText
+        public override LocalisableString TooltipText
         {
             get
             {

osu.Game/Screens/OnlinePlay/Playlists/AddPlaylistToCollectionButton.cs

@@ -5,7 +5,6 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using osu.Framework.Allocation;
-using osu.Framework.Graphics.Cursor;
 using osu.Framework.Localisation;
 using osu.Game.Beatmaps;
 using osu.Game.Collections;
@@ -18,7 +17,7 @@ using Realms;
 
 namespace osu.Game.Screens.OnlinePlay.Playlists
 {
-    public partial class AddPlaylistToCollectionButton : RoundedButton, IHasTooltip
+    public partial class AddPlaylistToCollectionButton : RoundedButton
     {
         private readonly Room room;
 
@@ -161,7 +160,7 @@ namespace osu.Game.Screens.OnlinePlay.Playlists
             collectionSubscription?.Dispose();
         }
 
-        public LocalisableString TooltipText
+        public override LocalisableString TooltipText
         {
             get
             {