Enforce readonly private members where possible.

osu.Game/Screens/Select/BeatmapCarousel.cs

@@ -60,18 +60,18 @@ namespace osu.Game.Screens.Select
             }
         }
 
-        private List<float> yPositions = new List<float>();
+        private readonly List<float> yPositions = new List<float>();
 
         /// <summary>
         /// Required for now unfortunately.
         /// </summary>
         private BeatmapDatabase database;
 
-        private Container<Panel> scrollableContent;
+        private readonly Container<Panel> scrollableContent;
 
-        private List<BeatmapGroup> groups = new List<BeatmapGroup>();
+        private readonly List<BeatmapGroup> groups = new List<BeatmapGroup>();
 
-        private List<Panel> panels = new List<Panel>();
+        private readonly List<Panel> panels = new List<Panel>();
 
         private BeatmapGroup selectedGroup;
 

osu.Game/Screens/Select/FilterControl.cs

@@ -24,9 +24,9 @@ namespace osu.Game.Screens.Select
     {
         public Action<FilterCriteria> FilterChanged;
 
-        private OsuTabControl<SortMode> sortTabs;
+        private readonly OsuTabControl<SortMode> sortTabs;
 
-        private TabControl<GroupMode> groupTabs;
+        private readonly TabControl<GroupMode> groupTabs;
 
         private SortMode sort = SortMode.Title;
         public SortMode Sort
@@ -66,7 +66,7 @@ namespace osu.Game.Screens.Select
 
         public Action Exit;
 
-        private SearchTextBox searchTextBox;
+        private readonly SearchTextBox searchTextBox;
 
         protected override bool InternalContains(Vector2 screenSpacePos) => base.InternalContains(screenSpacePos) || groupTabs.Contains(screenSpacePos) || sortTabs.Contains(screenSpacePos);
 

osu.Game/Screens/Select/Footer.cs

@@ -17,7 +17,7 @@ namespace osu.Game.Screens.Select
 {
     public class Footer : Container
     {
-        private Box modeLight;
+        private readonly Box modeLight;
 
         private const float play_song_select_button_width = 100;
         private const float play_song_select_button_height = 50;
@@ -29,7 +29,7 @@ namespace osu.Game.Screens.Select
         public Action OnBack;
         public Action OnStart;
 
-        private FillFlowContainer buttons;
+        private readonly FillFlowContainer buttons;
 
         public OsuLogo StartButton;
 

osu.Game/Screens/Select/FooterButton.cs

@@ -51,9 +51,9 @@ namespace osu.Game.Screens.Select
             }
         }
 
-        private SpriteText spriteText;
-        private Box box;
-        private Box light;
+        private readonly SpriteText spriteText;
+        private readonly Box box;
+        private readonly Box light;
 
         public FooterButton()
         {

osu.Game/Screens/Select/Leaderboards/DrawableRank.cs

@@ -13,7 +13,7 @@ namespace osu.Game.Screens.Select.Leaderboards
 {
     public class DrawableRank : Container
     {
-        private Sprite sprite;
+        private readonly Sprite sprite;
 
         public ScoreRank Rank { get; private set; }
 

osu.Game/Screens/Select/Leaderboards/Leaderboard.cs

@@ -16,8 +16,8 @@ namespace osu.Game.Screens.Select.Leaderboards
 {
     public class Leaderboard : Container
     {
-        private ScrollContainer scrollContainer;
-        private FillFlowContainer<LeaderboardScore> scrollFlow;
+        private readonly ScrollContainer scrollContainer;
+        private readonly FillFlowContainer<LeaderboardScore> scrollFlow;
 
         private IEnumerable<Score> scores;
         public IEnumerable<Score> Scores

osu.Game/Screens/Select/Leaderboards/LeaderboardScore.cs

@@ -30,14 +30,16 @@ namespace osu.Game.Screens.Select.Leaderboards
         private const float background_alpha = 0.25f;
         private const float rank_width = 30;
 
-        private Box background;
-        private Container content, avatar;
-        private DrawableRank scoreRank;
-        private OsuSpriteText nameLabel;
-        private GlowingSpriteText scoreLabel;
-        private ScoreComponentLabel maxCombo, accuracy;
-        private Container flagBadgeContainer;
-        private FillFlowContainer<ScoreModIcon> modsContainer;
+        private readonly Box background;
+        private readonly Container content;
+        private readonly Container avatar;
+        private readonly DrawableRank scoreRank;
+        private readonly OsuSpriteText nameLabel;
+        private readonly GlowingSpriteText scoreLabel;
+        private readonly ScoreComponentLabel maxCombo;
+        private readonly ScoreComponentLabel accuracy;
+        private readonly Container flagBadgeContainer;
+        private readonly FillFlowContainer<ScoreModIcon> modsContainer;
 
         private Visibility state;
         public Visibility State

osu.Game/Screens/Select/Options/BeatmapOptionsButton.cs

@@ -20,10 +20,12 @@ namespace osu.Game.Screens.Select.Options
     {
         private static readonly float width = 130;
 
-        private Box background, flash;
-        private TextAwesome iconText;
-        private OsuSpriteText firstLine, secondLine;
-        private Container box;
+        private readonly Box background;
+        private readonly Box flash;
+        private readonly TextAwesome iconText;
+        private readonly OsuSpriteText firstLine;
+        private readonly OsuSpriteText secondLine;
+        private readonly Container box;
 
         public Color4 ButtonColour
         {

osu.Game/Screens/Select/Options/BeatmapOptionsOverlay.cs

@@ -24,8 +24,8 @@ namespace osu.Game.Screens.Select.Options
 
         private const float height = 100;
 
-        private Box holder;
-        private FillFlowContainer<BeatmapOptionsButton> buttonsContainer;
+        private readonly Box holder;
+        private readonly FillFlowContainer<BeatmapOptionsButton> buttonsContainer;
 
         protected override void PopIn()
         {

osu.Game/Screens/Select/PlaySongSelect.cs

@@ -19,8 +19,8 @@ namespace osu.Game.Screens.Select
     public class PlaySongSelect : SongSelect
     {
         private OsuScreen player;
-        private ModSelectOverlay modSelect;
-        private Leaderboard leaderboard;
+        private readonly ModSelectOverlay modSelect;
+        private readonly Leaderboard leaderboard;
 
         public PlaySongSelect()
         {

osu.Game/Screens/Select/SongSelect.cs

@@ -31,20 +31,19 @@ namespace osu.Game.Screens.Select
 {
     public abstract class SongSelect : OsuScreen
     {
-        private Bindable<PlayMode> playMode = new Bindable<PlayMode>();
+        private readonly Bindable<PlayMode> playMode = new Bindable<PlayMode>();
         private BeatmapDatabase database;
         protected override BackgroundScreen CreateBackground() => new BackgroundScreenBeatmap(Beatmap);
 
-        private BeatmapCarousel carousel;
+        private readonly BeatmapCarousel carousel;
         private TrackManager trackManager;
         private DialogOverlay dialogOverlay;
 
-
         private static readonly Vector2 wedged_container_size = new Vector2(0.5f, 245);
 
         private const float left_area_padding = 20;
 
-        private BeatmapInfoWedge beatmapInfoWedge;
+        private readonly BeatmapInfoWedge beatmapInfoWedge;
 
         protected Container LeftContent;