IsEnabled property for drag bar of music controller.

osu.Game/Overlays/DragBar.cs

@@ -16,6 +16,18 @@ namespace osu.Game.Overlays
         public Action<float> SeekRequested;
         private bool isDragging;
 
+        private bool enabled;
+        public bool IsEnabled
+        {
+            get { return enabled; }
+            set
+            {
+                enabled = value;
+                if (!enabled)
+                    fill.Width = 0;
+            }
+        }
+
         public DragBar()
         {
             RelativeSizeAxes = Axes.X;
@@ -34,13 +46,14 @@ namespace osu.Game.Overlays
 
         public void UpdatePosition(float position)
         {
-            if (isDragging) return;
+            if (isDragging || !IsEnabled) return;
 
             fill.Width = position;
         }
 
         private void seek(InputState state)
         {
+            if (!IsEnabled) return;
             float seekLocation = state.Mouse.Position.X / DrawWidth;
             SeekRequested?.Invoke(seekLocation);
             fill.Width = seekLocation;

osu.Game/Overlays/MusicController.cs

@@ -240,6 +240,7 @@ namespace osu.Game.Overlays
 
         private void workingChanged(object sender = null, EventArgs e = null)
         {
+            progress.IsEnabled = (beatmapSource.Value != null);
             if (beatmapSource.Value == current) return;
             bool audioEquals = current?.BeatmapInfo.AudioEquals(beatmapSource.Value.BeatmapInfo) ?? false;
             current = beatmapSource.Value;