Simplify the way multiple subscreens handle their disable states via a custom stack

osu.Game/Screens/Multi/Lounge/LoungeSubScreen.cs

@@ -91,6 +91,22 @@ namespace osu.Game.Screens.Multi.Lounge
         public override void OnEntering(IScreen last)
         {
             base.OnEntering(last);
+
+            onReturning();
+        }
+
+        public override void OnResuming(IScreen last)
+        {
+            base.OnResuming(last);
+
+            if (currentRoom.Value?.RoomID.Value == null)
+                currentRoom.Value = new Room();
+
+            onReturning();
+        }
+
+        private void onReturning()
+        {
             Filter.Search.HoldFocus = true;
         }
 
@@ -106,14 +122,6 @@ namespace osu.Game.Screens.Multi.Lounge
             Filter.Search.HoldFocus = false;
         }
 
-        public override void OnResuming(IScreen last)
-        {
-            base.OnResuming(last);
-
-            if (currentRoom.Value?.RoomID.Value == null)
-                currentRoom.Value = new Room();
-        }
-
         private void joinRequested(Room room)
         {
             processingOverlay.Show();

osu.Game/Screens/Multi/Multiplayer.cs

@@ -32,6 +32,8 @@ namespace osu.Game.Screens.Multi
     {
         public override bool CursorVisible => (screenStack.CurrentScreen as IMultiplayerSubScreen)?.CursorVisible ?? true;
 
+        // this is required due to PlayerLoader eventually being pushed to the main stack
+        // while leases may be taken out by a subscreen.
         public override bool DisallowExternalBeatmapRulesetChanges => true;
 
         private readonly MultiplayerWaveContainer waves;
@@ -96,7 +98,7 @@ namespace osu.Game.Screens.Multi
                     {
                         RelativeSizeAxes = Axes.Both,
                         Padding = new MarginPadding { Top = Header.HEIGHT },
-                        Child = screenStack = new OsuScreenStack { RelativeSizeAxes = Axes.Both }
+                        Child = screenStack = new MultiplayerSubScreenStack { RelativeSizeAxes = Axes.Both }
                     },
                     new Header(screenStack),
                     createButton = new HeaderButton
@@ -277,11 +279,7 @@ namespace osu.Game.Screens.Multi
 
         private void updateTrack(ValueChangedEvent<WorkingBeatmap> _ = null)
         {
-            bool isMatch = screenStack.CurrentScreen is MatchSubScreen;
+            if (screenStack.CurrentScreen is MatchSubScreen)
-
-            Beatmap.Disabled = isMatch;
-
-            if (isMatch)
             {
                 var track = Beatmap.Value?.Track;
 

osu.Game/Screens/Multi/MultiplayerSubScreenStack.cs

@@ -0,0 +1,24 @@
+// 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 osu.Framework.Screens;
+
+namespace osu.Game.Screens.Multi
+{
+    public class MultiplayerSubScreenStack : OsuScreenStack
+    {
+        protected override void ScreenChanged(IScreen prev, IScreen next)
+        {
+            base.ScreenChanged(prev, next);
+
+            // because this is a screen stack within a screen stack, let's manually handle disabled changes to simplify things.
+            var osuScreen = ((OsuScreen)next);
+
+            bool disallowChanges = osuScreen.DisallowExternalBeatmapRulesetChanges;
+
+            osuScreen.Beatmap.Disabled = disallowChanges;
+            osuScreen.Ruleset.Disabled = disallowChanges;
+            osuScreen.Mods.Disabled = disallowChanges;
+        }
+    }
+}

osu.Game/Screens/OsuScreenStack.cs

@@ -26,7 +26,7 @@ namespace osu.Game.Screens
             };
 
             ScreenPushed += screenPushed;
-            ScreenExited += screenExited;
+            ScreenExited += ScreenChanged;
         }
 
         private void screenPushed(IScreen prev, IScreen next)
@@ -42,10 +42,10 @@ namespace osu.Game.Screens
             // create dependencies synchronously to ensure leases are in a sane state.
             ((OsuScreen)next).CreateLeasedDependencies((prev as OsuScreen)?.Dependencies ?? Dependencies);
 
-            setParallax(next);
+            ScreenChanged(prev, next);
         }
 
-        private void screenExited(IScreen prev, IScreen next)
+        protected virtual void ScreenChanged(IScreen prev, IScreen next)
         {
             setParallax(next);
         }

osu.Game/Screens/Select/MatchSongSelect.cs

@@ -65,20 +65,7 @@ namespace osu.Game.Screens.Select
                 Mods.Value = CurrentItem.Value.RequiredMods?.ToArray() ?? Array.Empty<Mod>();
             }
 
-            Beatmap.Disabled = true;
-            Ruleset.Disabled = true;
-            Mods.Disabled = true;
-
             return false;
         }
-
-        public override void OnEntering(IScreen last)
-        {
-            base.OnEntering(last);
-
-            Beatmap.Disabled = false;
-            Ruleset.Disabled = false;
-            Mods.Disabled = false;
-        }
     }
 }