Fix argon key area lighting being hidden by other columns in one direction

osu.Game.Rulesets.Mania/Skinning/Argon/ArgonHitExplosion.cs

@@ -17,8 +17,6 @@ namespace osu.Game.Rulesets.Mania.Skinning.Argon
 {
     public class ArgonHitExplosion : CompositeDrawable, IHitExplosion
     {
-        private const float default_large_faint_size = 0.8f;
-
         public override bool RemoveWhenNotAlive => true;
 
         [Resolved]

osu.Game.Rulesets.Mania/Skinning/Argon/ArgonKeyArea.cs

@@ -150,6 +150,9 @@ namespace osu.Game.Rulesets.Mania.Skinning.Argon
                     bottomIcon.Colour = colour.NewValue;
                 },
                 true);
+
+            // Yes, proxy everything.
+            column.TopLevelContainer.Add(CreateProxy());
         }
 
         private void onDirectionChanged(ValueChangedEvent<ScrollingDirection> direction)