Add slider placement binding description in tooltip

osu.Game.Rulesets.Osu/Edit/SliderCompositionTool.cs

@@ -15,6 +15,13 @@ namespace osu.Game.Rulesets.Osu.Edit
         public SliderCompositionTool()
             : base(nameof(Slider))
         {
+            TooltipText = """
+                Left click for new point.
+                Left click twice or S key for new segment.
+                Tab, Shift-Tab, or Alt-1~4 to change current segment type.
+                Right click to finish.
+                Click and drag for drawing mode.
+                """;
         }
 
         public override Drawable CreateIcon() => new BeatmapStatisticIcon(BeatmapStatisticsIconType.Sliders);

osu.Game/Rulesets/Edit/HitObjectComposer.cs

@@ -215,14 +215,14 @@ namespace osu.Game.Rulesets.Edit
 
             toolboxCollection.Items = CompositionTools
                                       .Prepend(new SelectTool())
-                                      .Select(t => new RadioButton(t.Name, () => toolSelected(t), t.CreateIcon))
+                                      .Select(t => new HitObjectCompositionToolButton(t, () => toolSelected(t)))
                                       .ToList();
 
             foreach (var item in toolboxCollection.Items)
             {
                 item.Selected.DisabledChanged += isDisabled =>
                 {
-                    item.TooltipText = isDisabled ? "Add at least one timing point first!" : string.Empty;
+                    item.TooltipText = isDisabled ? "Add at least one timing point first!" : ((HitObjectCompositionToolButton)item).TooltipText;
                 };
             }
 

osu.Game/Rulesets/Edit/HitObjectCompositionToolButton.cs

@@ -0,0 +1,22 @@
+// 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;
+using osu.Game.Rulesets.Edit.Tools;
+using osu.Game.Screens.Edit.Components.RadioButtons;
+
+namespace osu.Game.Rulesets.Edit
+{
+    public class HitObjectCompositionToolButton : RadioButton
+    {
+        public HitObjectCompositionTool Tool { get; }
+
+        public HitObjectCompositionToolButton(HitObjectCompositionTool tool, Action? action)
+            : base(tool.Name, action, tool.CreateIcon)
+        {
+            Tool = tool;
+
+            TooltipText = tool.TooltipText;
+        }
+    }
+}

osu.Game/Rulesets/Edit/Tools/HitObjectCompositionTool.cs

@@ -1,9 +1,8 @@
 // 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.Graphics;
+using osu.Framework.Localisation;
 
 namespace osu.Game.Rulesets.Edit.Tools
 {
@@ -11,6 +10,8 @@ namespace osu.Game.Rulesets.Edit.Tools
     {
         public readonly string Name;
 
+        public LocalisableString TooltipText { get; init; } = default;
+
         protected HitObjectCompositionTool(string name)
         {
             Name = name;
@@ -18,7 +19,7 @@ namespace osu.Game.Rulesets.Edit.Tools
 
         public abstract PlacementBlueprint CreatePlacementBlueprint();
 
-        public virtual Drawable CreateIcon() => null;
+        public virtual Drawable? CreateIcon() => null;
 
         public override string ToString() => Name;
     }

osu.Game/Screens/Edit/Components/RadioButtons/RadioButton.cs

@@ -24,11 +24,11 @@ namespace osu.Game.Screens.Edit.Components.RadioButtons
         /// <summary>
         /// A function which creates a drawable icon to represent this item. If null, a sane default should be used.
         /// </summary>
-        public readonly Func<Drawable>? CreateIcon;
+        public readonly Func<Drawable?>? CreateIcon;
 
         private readonly Action? action;
 
-        public RadioButton(string label, Action? action, Func<Drawable>? createIcon = null)
+        public RadioButton(string label, Action? action, Func<Drawable?>? createIcon = null)
         {
             Label = label;
             CreateIcon = createIcon;