TrackPanel listens for Undo events, doesn't intrude in ProjectHistory

src/ProjectHistory.cpp

@@ -15,7 +15,6 @@ Paul Licameli split from ProjectManager.cpp
 #include "ProjectFileIO.h"
 #include "Tags.h"
 #include "Track.h"
-#include "TrackPanel.h"
 #include "UndoManager.h"
 #include "ViewInfo.h"
 #include "ondemand/ODComputeSummaryTask.h"
@@ -183,12 +182,8 @@ void ProjectHistory::PopState(const UndoState &state)
 void ProjectHistory::SetStateTo(unsigned int n)
 {
    auto &project = mProject;
-   auto &trackPanel = TrackPanel::Get( project );
    auto &undoManager = UndoManager::Get( project );
 
    undoManager.SetStateTo(n,
       [this]( const UndoState &state ){ PopState(state); } );
-
-   trackPanel.SetFocusedTrack(NULL);
-   trackPanel.Refresh(false);
 }

src/TrackPanel.cpp

@@ -78,6 +78,8 @@ is time to refresh some aspect of the screen.
 #include "TrackPanelResizeHandle.h"
 //#define DEBUG_DRAW_TIMING 1
 
+#include "UndoManager.h"
+
 #include "AColor.h"
 #include "AllThemeResources.h"
 #include "AudioIO.h"
@@ -320,6 +322,8 @@ TrackPanel::TrackPanel(wxWindow * parent, wxWindowID id,
    theProject->Bind(
       EVT_PROJECT_SETTINGS_CHANGE, &TrackPanel::OnProjectSettingsChange, this);
 
+   theProject->Bind(EVT_UNDO_RESET, &TrackPanel::OnUndoReset, this);
+
    UpdatePrefs();
 }
 
@@ -554,6 +558,13 @@ double TrackPanel::GetScreenEndTime() const
    return mViewInfo->PositionToTime(width, 0, true);
 }
 
+void TrackPanel::OnUndoReset( wxCommandEvent &event )
+{
+   event.Skip();
+   SetFocusedTrack( nullptr );
+   Refresh( false );
+}
+
 /// AS: OnPaint( ) is called during the normal course of
 ///  completing a repaint operation.
 void TrackPanel::OnPaint(wxPaintEvent & /* event */)

src/TrackPanel.h

@@ -295,6 +295,8 @@ class AUDACITY_DLL_API TrackPanel final
    // Either argument may be NULL
    void GetTracksUsableArea(int *width, int *height) const;
 
+   void OnUndoReset( wxCommandEvent &event );
+
    void Refresh
       (bool eraseBackground = true, const wxRect *rect = (const wxRect *) NULL)
       override;