Define CellularPanel::Root

src/CellularPanel.h

@@ -18,6 +18,7 @@ class ViewInfo;
 class AudacityProject;
 
 class TrackPanelCell;
+class TrackPanelNode;
 struct TrackPanelMouseEvent;
 struct TrackPanelMouseState;
 
@@ -47,6 +48,11 @@ public:
       std::shared_ptr<TrackPanelCell> pCell;
       wxRect rect;
    };
+
+   // Get the root object defining a recursive subdivision of the panel's
+   // area into cells
+   virtual std::shared_ptr<TrackPanelNode> Root() = 0;
+
    virtual FoundCell FindCell(int mouseX, int mouseY) = 0;
    virtual wxRect FindRect(const TrackPanelCell &cell) = 0;
    virtual TrackPanelCell *GetFocusedCell() = 0;