Merge pull request #3396 from peppy/music-controller-topmost

Bring music controller in front of notification overlay

osu.Game/OsuGame.cs

@@ -355,7 +355,7 @@ namespace osu.Game
             loadComponentSingleFile(beatmapSetOverlay = new BeatmapSetOverlay { Depth = -3 }, mainContent.Add);
             loadComponentSingleFile(musicController = new MusicController
             {
-                Depth = -4,
+                Depth = -5,
                 Position = new Vector2(0, Toolbar.HEIGHT),
                 Anchor = Anchor.TopRight,
                 Origin = Anchor.TopRight,