Defaulting TrackPanel cursor, status message; simplifies other code

src/TrackPanel.cpp

@@ -928,6 +928,10 @@ void TrackPanel::HandleMotion( const TrackPanelMouseState &tpmState )
       refreshCode |= code;
       mMouseOverUpdateFlags |= code;
    }
+   if (!pCursor) {
+      static wxCursor defaultCursor{ wxCURSOR_ARROW };
+      pCursor = &defaultCursor;
+   }
    mListener->TP_DisplayStatusMessage(tip);
    if (pCursor)
       SetCursor( *pCursor );

src/tracks/playabletrack/notetrack/ui/NoteTrackSliderHandles.cpp

@@ -86,7 +86,7 @@ HitTestResult VelocitySliderHandle::HitTest
          sliderFn, sliderRect, pTrack );
       result = AssignUIHandlePtr(holder, result);
 
-      return { HitPreview(), result };
+      return { HitTestPreview{}, result };
    }
    else
       return {};

src/tracks/playabletrack/ui/PlayableTrackButtonHandles.cpp

@@ -53,7 +53,7 @@ HitTestResult MuteButtonHandle::HitTest
       auto result = std::make_shared<MuteButtonHandle>(pTrack, buttonRect);
       result = AssignUIHandlePtr(holder, result);
       return {
-         HitPreview(),
+         HitTestPreview{},
          result
       };
    }
@@ -99,7 +99,7 @@ HitTestResult SoloButtonHandle::HitTest
       auto result = std::make_shared<SoloButtonHandle>( pTrack, buttonRect );
       result = AssignUIHandlePtr(holder, result);
       return HitTestResult(
-         HitPreview(),
+         HitTestPreview{},
          result
       );
    }

src/tracks/playabletrack/wavetrack/ui/WaveTrackSliderHandles.cpp

@@ -89,7 +89,7 @@ HitTestResult GainSliderHandle::HitTest
       result = AssignUIHandlePtr(holder, result);
 
       return {
-         HitPreview(),
+         HitTestPreview{},
          result
       };
    }
@@ -179,7 +179,7 @@ HitTestResult PanSliderHandle::HitTest
       result = AssignUIHandlePtr(holder, result);
 
       return {
-         HitPreview(),
+         HitTestPreview{},
          result
       };
    }

src/tracks/ui/ButtonHandle.cpp

@@ -31,12 +31,6 @@ ButtonHandle::~ButtonHandle()
 {
 }
 
-HitTestPreview ButtonHandle::HitPreview()
-{
-   static wxCursor arrowCursor{ wxCURSOR_ARROW };
-   return { {}, &arrowCursor };
-}
-
 UIHandle::Result ButtonHandle::Click
 (const TrackPanelMouseEvent &evt, AudacityProject *pProject)
 {

src/tracks/ui/ButtonHandle.h

@@ -38,9 +38,6 @@ protected:
    virtual Result CommitChanges
       (const wxMouseEvent &event, AudacityProject *pProject, wxWindow *pParent) = 0;
 
-   // For derived class to define hit tests
-   static HitTestPreview HitPreview();
-
    Result Click
       (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;
 

src/tracks/ui/SliderHandle.cpp

@@ -27,12 +27,6 @@ SliderHandle::~SliderHandle()
 {
 }
 
-HitTestPreview SliderHandle::HitPreview()
-{
-   // No special message or cursor
-   return {};
-}
-
 UIHandle::Result SliderHandle::Click
 (const TrackPanelMouseEvent &evt, AudacityProject *pProject)
 {

src/tracks/ui/SliderHandle.h

@@ -44,9 +44,6 @@ protected:
    virtual Result CommitChanges
       (const wxMouseEvent &event, AudacityProject *pProject) = 0;
 
-   // For derived classes to define hit tests
-   static HitTestPreview HitPreview();
-
    Result Click
       (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;
 

src/tracks/ui/TrackButtonHandles.cpp

@@ -60,7 +60,7 @@ HitTestResult MinimizeButtonHandle::HitTest
       auto result = std::make_shared<MinimizeButtonHandle>( pTrack, buttonRect );
       result = AssignUIHandlePtr(holder, result);
       return {
-         HitPreview(),
+         HitTestPreview{},
          result
       };
    }
@@ -114,7 +114,7 @@ HitTestResult CloseButtonHandle::HitTest
       auto result = std::make_shared<CloseButtonHandle>( pTrack, buttonRect );
       result = AssignUIHandlePtr(holder, result);
       return {
-         HitPreview(),
+         HitTestPreview{},
          result
       };
    }
@@ -157,7 +157,7 @@ HitTestResult MenuButtonHandle::HitTest
       auto result = std::make_shared<MenuButtonHandle>( pCell, pTrack, buttonRect );
       result = AssignUIHandlePtr(holder, result);
       return {
-         HitPreview(),
+         HitTestPreview{},
          result
       };
    }

src/tracks/ui/TrackVRulerControls.cpp

@@ -35,9 +35,7 @@ std::shared_ptr<Track> TrackVRulerControls::FindTrack()
 HitTestResult TrackVRulerControls::HitTest
 (const TrackPanelMouseState &, const AudacityProject *)
 {
-   // Use a space for the tip, otherwise we get the default message.
-   static wxCursor arrowCursor{ wxCURSOR_ARROW };
-   return { { _(" "), &arrowCursor }, {} };
+   return {};
 }
 
 void TrackVRulerControls::DrawZooming