43   panel: TrackPanel;  property
48   panel: TrackGroupPanel;  property
78   registerPanel(panel: PanelVNode, yStart: number, height: number) {
79     if (panel.state instanceof TrackPanel && hasId(panel.attrs)) {
80       const config = globals.state.tracks[panel.attrs.id].config;  constant
83             config.trackId, {panel: panel.state, yStart});
87           this.trackIdToTrackPanel.set(trackId, {panel: panel.state, yStart});
91         panel.state instanceof TrackGroupPanel &&
92         hasTrackGroupId(panel.attrs)) {
94           panel.attrs.trackGroupId, {panel: panel.state, yStart, height});
149     const trackPanel = args.trackIdToTrackPanel.get(point.trackId) ?.panel;