Demote Copy to CommonTrackCell; Track points only to that base class

src/Track.h

@@ -263,8 +263,8 @@ class AUDACITY_DLL_API Track /* not final */
 
    // Return another, associated TrackPanelCell object that implements
    // click and drag and keystrokes in the track contents.
-   std::shared_ptr<TrackView> GetTrackView();
-   std::shared_ptr<const TrackView> GetTrackView() const;
+   std::shared_ptr<CommonTrackCell> GetTrackView();
+   std::shared_ptr<const CommonTrackCell> GetTrackView() const;
 
    // Return another, associated TrackPanelCell object that implements the
    // drop-down, close and minimize buttons, etc.
@@ -704,7 +704,7 @@ public:
    bool HandleCommonXMLAttribute(const wxChar *attr, const wxChar *value);
 
 protected:
-   std::shared_ptr<TrackView> mpView;
+   std::shared_ptr<CommonTrackCell> mpView;
    std::shared_ptr<CommonTrackCell> mpControls;
 };
 

src/tracks/labeltrack/ui/LabelTrackView.cpp

@@ -97,7 +97,7 @@ void LabelTrackView::UnbindFrom( LabelTrack *pParent )
       EVT_LABELTRACK_PERMUTED, &LabelTrackView::OnLabelPermuted, this );
 }
 
-void LabelTrackView::Copy( const TrackView &other )
+void LabelTrackView::Copy( const CommonTrackCell &other )
 {
    TrackView::Copy( other );
 

src/tracks/labeltrack/ui/LabelTrackView.h

@@ -82,7 +82,7 @@ private:
    std::shared_ptr<TrackVRulerControls> DoGetVRulerControls() override;
 
    // Preserve some view state too for undo/redo purposes
-   void Copy( const TrackView &other ) override;
+   void Copy( const CommonTrackCell &other ) override;
 
 public:
    static void DoEditLabels(

src/tracks/ui/CommonTrackPanelCell.cpp

@@ -57,6 +57,10 @@ CommonTrackCell::CommonTrackCell( const std::shared_ptr< Track > &parent )
 
 CommonTrackCell::~CommonTrackCell() = default;
 
+void CommonTrackCell::Copy( const CommonTrackCell & )
+{
+}
+
 void CommonTrackCell::Reparent( const std::shared_ptr<Track> &parent )
 {
    mwTrack = parent;

src/tracks/ui/CommonTrackPanelCell.h

@@ -62,6 +62,9 @@ public:
 
   ~CommonTrackCell();
 
+   // Copy state, for undo/redo purposes
+   virtual void Copy( const CommonTrackCell &other );
+
    std::shared_ptr<Track> DoFindTrack() override;
 
    virtual void Reparent( const std::shared_ptr<Track> &parent );

src/tracks/ui/TrackView.cpp

@@ -46,8 +46,13 @@ int TrackView::GetTotalHeight( const TrackList &list )
    return GetCumulativeHeight( *list.Any().rbegin() );
 }
 
-void TrackView::Copy( const TrackView &other )
+void TrackView::Copy( const CommonTrackCell &otherCell )
 {
+   auto pOther = dynamic_cast< const TrackView* >( &otherCell );
+   if ( !pOther )
+      return;
+   auto &other = *pOther;
+
    mMinimized = other.mMinimized;
 
    // Let mY remain 0 -- TrackPositioner corrects it later
@@ -57,12 +62,12 @@ void TrackView::Copy( const TrackView &other )
 
 TrackView &TrackView::Get( Track &track )
 {
-   return *track.GetTrackView();
+   return static_cast<TrackView&>( *track.GetTrackView() );
 }
 
 const TrackView &TrackView::Get( const Track &track )
 {
-   return *track.GetTrackView();
+   return static_cast<const TrackView&>( *track.GetTrackView() );
 }
 
 void TrackView::SetMinimized(bool isMinimized)
@@ -105,7 +110,7 @@ void TrackView::DoSetMinimized(bool isMinimized)
    mMinimized = isMinimized;
 }
 
-std::shared_ptr<TrackView> Track::GetTrackView()
+std::shared_ptr<CommonTrackCell> Track::GetTrackView()
 {
    if (!mpView)
       // create on demand
@@ -113,7 +118,7 @@ std::shared_ptr<TrackView> Track::GetTrackView()
    return mpView;
 }
 
-std::shared_ptr<const TrackView> Track::GetTrackView() const
+std::shared_ptr<const CommonTrackCell> Track::GetTrackView() const
 {
    return const_cast<Track*>(this)->GetTrackView();
 }

src/tracks/ui/TrackView.h

@@ -42,7 +42,7 @@ public:
    static int GetTotalHeight( const TrackList &list );
 
    // Copy view state, for undo/redo purposes
-   virtual void Copy( const TrackView &other );
+   void Copy( const CommonTrackCell &other ) override;
 
    static TrackView &Get( Track & );
    static const TrackView &Get( const Track & );