public override void OnInspectorGUI()
                {
                    foreach (Object target in base.targets)
                    {
                        LegacyAnimatorTrack track = target as LegacyAnimatorTrack;
                        if (track == null)
                        {
                            break;
                        }

                        if (!(track.parent is TimelineAsset))
                        {
                            break;
                        }

                        GUILayout.Label(track.name, EditorStyles.boldLabel);

                        EditorGUILayout.PropertyField(_channelProperty, new GUIContent("Base Animation Channel"));

                        EditorGUILayout.Separator();

                        GUILayout.Label(new GUIContent("Additional Animation Layers"), EditorStyles.boldLabel);

                        IEnumerable <TrackAsset> childTracks = track.GetChildTracks();
                        _channelTracks.list = new List <TrackAsset>(childTracks);
                        _channelTracks.DoLayoutList();
                        _channelTracks.index = -1;
                    }

                    serializedObject.ApplyModifiedProperties();
                }
                protected virtual void AddChanelToTrack(LegacyAnimatorTrack animatorTrack)
                {
                    if (animatorTrack != null)
                    {
                        //Work out next free channel to add
                        int channel = _channelProperty.intValue + 1;

                        foreach (LegacyAnimatorTrack track in animatorTrack.GetChildTracks())
                        {
                            if (track != null)
                            {
                                channel = Mathf.Max(channel, track._animationChannel + 1);
                            }
                        }

                        LegacyAnimatorTrack newTrack = TimelineEditorUtils.CreateChildTrack <LegacyAnimatorTrack>(animatorTrack, "Channel " + channel);
                        newTrack._animationChannel = channel;
                    }
                }