class MoveTracksDown;
class DeleteTracks;
class ConcatenateTracks;
class MoveTracksDown;
class DeleteTracks;
class ConcatenateTracks;
+class DeleteFirstTrack;
+class DeleteLastTrack;
class LoopPlayback;
class SetBRenderActive;
class LabelsFollowEdits;
class LoopPlayback;
class SetBRenderActive;
class LabelsFollowEdits;