Fix checkbox not being updated

osu.Game/Overlays/Mods/ModSection.cs

@@ -23,13 +23,15 @@ namespace osu.Game.Overlays.Mods
 
         public FillFlowContainer<ModButtonEmpty> ButtonsContainer { get; }
 
+        protected IReadOnlyList<ModButton> Buttons { get; private set; } = Array.Empty<ModButton>();
+
         public Action<Mod> Action;
 
         public Key[] ToggleKeys;
 
         public readonly ModType ModType;
 
-        public IEnumerable<Mod> SelectedMods => buttons.Select(b => b.SelectedMod).Where(m => m != null);
+        public IEnumerable<Mod> SelectedMods => Buttons.Select(b => b.SelectedMod).Where(m => m != null);
 
         private CancellationTokenSource modsLoadCts;
 
@@ -77,7 +79,7 @@ namespace osu.Game.Overlays.Mods
                     ButtonsContainer.ChildrenEnumerable = c;
                 }, (modsLoadCts = new CancellationTokenSource()).Token);
 
-                buttons = modContainers.OfType<ModButton>().ToArray();
+                Buttons = modContainers.OfType<ModButton>().ToArray();
 
                 header.FadeIn(200);
                 this.FadeIn(200);
@@ -88,8 +90,6 @@ namespace osu.Game.Overlays.Mods
         {
         }
 
-        private ModButton[] buttons = Array.Empty<ModButton>();
-
         protected override bool OnKeyDown(KeyDownEvent e)
         {
             if (e.ControlPressed) return false;
@@ -97,8 +97,8 @@ namespace osu.Game.Overlays.Mods
             if (ToggleKeys != null)
             {
                 var index = Array.IndexOf(ToggleKeys, e.Key);
-                if (index > -1 && index < buttons.Length)
+                if (index > -1 && index < Buttons.Count)
-                    buttons[index].SelectNext(e.ShiftPressed ? -1 : 1);
+                    Buttons[index].SelectNext(e.ShiftPressed ? -1 : 1);
             }
 
             return base.OnKeyDown(e);
@@ -141,7 +141,7 @@ namespace osu.Game.Overlays.Mods
         {
             pendingSelectionOperations.Clear();
 
-            foreach (var button in buttons.Where(b => !b.Selected))
+            foreach (var button in Buttons.Where(b => !b.Selected))
                 pendingSelectionOperations.Enqueue(() => button.SelectAt(0));
         }
 
@@ -151,7 +151,7 @@ namespace osu.Game.Overlays.Mods
         public void DeselectAll()
         {
             pendingSelectionOperations.Clear();
-            DeselectTypes(buttons.Select(b => b.SelectedMod?.GetType()).Where(t => t != null));
+            DeselectTypes(Buttons.Select(b => b.SelectedMod?.GetType()).Where(t => t != null));
         }
 
         /// <summary>
@@ -161,7 +161,7 @@ namespace osu.Game.Overlays.Mods
         /// <param name="immediate">Whether the deselection should happen immediately. Should only be used when required to ensure correct selection flow.</param>
         public void DeselectTypes(IEnumerable<Type> modTypes, bool immediate = false)
         {
-            foreach (var button in buttons)
+            foreach (var button in Buttons)
             {
                 if (button.SelectedMod == null) continue;
 
@@ -184,7 +184,7 @@ namespace osu.Game.Overlays.Mods
         /// <param name="newSelectedMods">The new list of selected mods to select.</param>
         public void UpdateSelectedButtons(IReadOnlyList<Mod> newSelectedMods)
         {
-            foreach (var button in buttons)
+            foreach (var button in Buttons)
                 updateButtonSelection(button, newSelectedMods);
         }
 

osu.Game/Overlays/Mods/ModSelectOverlay.cs

@@ -456,6 +456,7 @@ namespace osu.Game.Overlays.Mods
             }
 
             updateSelectedButtons();
+            OnAvailableModsChanged();
         }
 
         /// <summary>
@@ -533,6 +534,13 @@ namespace osu.Game.Overlays.Mods
         private void playSelectedSound() => sampleOn?.Play();
         private void playDeselectedSound() => sampleOff?.Play();
 
+        /// <summary>
+        /// Invoked after <see cref="availableMods"/> has changed.
+        /// </summary>
+        protected virtual void OnAvailableModsChanged()
+        {
+        }
+
         /// <summary>
         /// Invoked when a new <see cref="Mod"/> has been selected.
         /// </summary>

osu.Game/Screens/OnlinePlay/FreeModSelectOverlay.cs

@@ -75,6 +75,14 @@ namespace osu.Game.Screens.OnlinePlay
                 section.DeselectAll();
         }
 
+        protected override void OnAvailableModsChanged()
+        {
+            base.OnAvailableModsChanged();
+
+            foreach (var section in ModSectionsContainer.Children)
+                ((FreeModSection)section).UpdateCheckboxState();
+        }
+
         protected override ModSection CreateModSection(ModType type) => new FreeModSection(type);
 
         private class FreeModSection : ModSection
@@ -108,10 +116,14 @@ namespace osu.Game.Screens.OnlinePlay
             protected override void ModButtonStateChanged(Mod mod)
             {
                 base.ModButtonStateChanged(mod);
+                UpdateCheckboxState();
+            }
 
+            public void UpdateCheckboxState()
+            {
                 if (!SelectionAnimationRunning)
                 {
-                    var validButtons = ButtonsContainer.OfType<ModButton>().Where(b => b.Mod.HasImplementation);
+                    var validButtons = Buttons.Where(b => b.Mod.HasImplementation);
                     checkbox.Current.Value = validButtons.All(b => b.Selected);
                 }
             }