44   trackGroupId: string;  property
49   private readonly trackGroupId: string;  property in TrackGroupPanel
56     this.trackGroupId = attrs.trackGroupId;
62     return assertExists(globals.state.trackGroups[this.trackGroupId]);
84       if (parentTrackId === attrs.trackGroupId) {
91     const trackGroup = globals.state.trackGroups[attrs.trackGroupId];
95       if (selectedArea.tracks.includes(attrs.trackGroupId) &&
99           selectedArea.tracks.includes(attrs.trackGroupId) ||
107         {id: 'track_' + this.trackGroupId},
112                 trackGroupId: attrs.trackGroupId,
132                         {id: attrs.trackGroupId, isTrackGroup: true}));
164     if (selectedArea.tracks.includes(this.trackGroupId)) {