Fixed sing-button in bg-popup.

Vocaluxe/Base/CBackgroundMusic.cs

@@ -60,7 +60,18 @@ namespace Vocaluxe.Base
             }
         }
 
-        public static bool CanSing { get { return _BGMusicFiles.Contains(_CurrentPlaylistElement) ? false : _SongPlayer.CanSing; } }
+        public static bool CanSing 
+        { 
+            get 
+            {
+                if (_PlaysPreview)
+                    return false;
+                else
+                    if (_BGMusicFiles.Contains(_CurrentPlaylistElement))
+                        return false;
+                    else return true;
+            } 
+        }
 
         public static bool Disabled
         {

VocaluxeLib/Utils/Player/CSongPlayer.cs

@@ -35,7 +35,6 @@ namespace VocaluxeLib.Utils.Player
                 }
             }
         }
-        public bool CanSing { get; private set; }
         public int SongID
         {
             get { return _Song == null ? -1 : _Song.ID; }