Handles mark need for highlight in new Enter() method not ctor...

... So this can be called more than once in its lifetime, in response to
TAB key rotation.

src/TrackPanel.cpp

@@ -916,6 +916,9 @@ void TrackPanel::HandleMotion( const TrackPanelMouseState &tpmState )
       if (!oldCell && oldHandle != handle)
          // Did not move cell to cell, but did change the target
          refreshCode = updateFlags;
+
+      if (handle)
+         handle->Enter();
    }
 
    // UIHANDLE PREVIEW

src/UIHandle.cpp

@@ -15,6 +15,10 @@ UIHandle::~UIHandle()
 {
 }
 
+void UIHandle::Enter()
+{
+}
+
 void UIHandle::DrawExtras
    (DrawingPass, wxDC *, const wxRegion &, const wxRect &)
 {

src/UIHandle.h

@@ -47,6 +47,10 @@ public:
 
    virtual ~UIHandle() = 0;
 
+   // Before clicking, the handle is notified that it has been "hit"
+   // Default does nothing.
+   virtual void Enter();
+
    // Assume hit test (implemented in other classes) was positive.
    // May return Cancelled, overriding the hit test decision and stopping drag.
    // Otherwise the framework will later call Release or Cancel after

src/tracks/labeltrack/ui/LabelGlyphHandle.cpp

@@ -29,6 +29,10 @@ LabelGlyphHandle::LabelGlyphHandle
    : mpLT{ pLT }
    , mRect{ rect }
    , mHit{ hit }
+{
+}
+
+void LabelGlyphHandle::Enter()
 {
    mChangeHighlight = RefreshCode::RefreshCell;
 }

src/tracks/labeltrack/ui/LabelGlyphHandle.h

@@ -54,6 +54,8 @@ public:
 
    virtual ~LabelGlyphHandle();
 
+   void Enter() override;
+
    Result Click
       (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;
 

src/tracks/labeltrack/ui/LabelTextHandle.cpp

@@ -24,6 +24,10 @@ LabelTextHandle::LabelTextHandle
    : mpLT{ pLT }
    , mLabelNum{ labelNum }
 {
+}
+
+void LabelTextHandle::Enter()
+{
 #ifdef EXPERIMENTAL_TRACK_PANEL_HIGHLIGHTING
    mChangeHighlight = RefreshCode::RefreshCell;
 #endif

src/tracks/labeltrack/ui/LabelTextHandle.h

@@ -38,6 +38,8 @@ public:
    std::shared_ptr<LabelTrack> GetTrack() const { return mpLT.lock(); }
    int GetLabelNum() const { return mLabelNum; }
 
+   void Enter() override;
+
    Result Click
       (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;
 

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

@@ -24,6 +24,10 @@ NoteTrackButtonHandle::NoteTrackButtonHandle
    : mpTrack{ pTrack }
    , mChannel{ channel }
    , mRect{ rect }
+{
+}
+
+void NoteTrackButtonHandle::Enter()
 {
    mChangeHighlight = RefreshCode::RefreshCell;
 }

src/tracks/playabletrack/notetrack/ui/NoteTrackButtonHandle.h

@@ -47,6 +47,8 @@ public:
        const NoteTrackButtonHandle &newState);
 
 protected:
+   void Enter() override;
+
    Result Click
       (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;
 

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

@@ -40,6 +40,10 @@ NoteTrackVZoomHandle::NoteTrackVZoomHandle
    : mZoomStart(y), mZoomEnd(y), mRect(rect)
    , mpTrack{ pTrack }
 {
+}
+
+void NoteTrackVZoomHandle::Enter()
+{
 #ifdef EXPERIMENTAL_TRACK_PANEL_HIGHLIGHTING
    mChangeHighlight = RefreshCode::RefreshCell;
 #endif

src/tracks/playabletrack/notetrack/ui/NoteTrackVZoomHandle.h

@@ -38,6 +38,8 @@ public:
 
    std::shared_ptr<NoteTrack> GetTrack() const { return mpTrack.lock(); }
 
+   void Enter() override;
+
    Result Click
       (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;
 

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

@@ -28,6 +28,10 @@ CutlineHandle::CutlineHandle
    : mpTrack{ pTrack }
    , mLocation{ location }
 {
+}
+
+void CutlineHandle::Enter()
+{
 #ifdef EXPERIMENTAL_TRACK_PANEL_HIGHLIGHTING
    mChangeHighlight = RefreshCode::RefreshCell;
 #endif

src/tracks/playabletrack/wavetrack/ui/CutlineHandle.h

@@ -45,6 +45,8 @@ public:
    const WaveTrackLocation &GetLocation() { return mLocation; }
    std::shared_ptr<WaveTrack> GetTrack() { return mpTrack; }
 
+   void Enter() override;
+
    Result Click
       (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;
 

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

@@ -38,6 +38,10 @@ static const double SMOOTHING_PROPORTION_MIN = 0.0;
 SampleHandle::SampleHandle( const std::shared_ptr<WaveTrack> &pTrack )
    : mClickedTrack{ pTrack }
 {
+}
+
+void SampleHandle::Enter()
+{
 #ifdef EXPERIMENTAL_TRACK_PANEL_HIGHLIGHTING
    mChangeHighlight = RefreshCode::RefreshCell;
 #endif

src/tracks/playabletrack/wavetrack/ui/SampleHandle.h

@@ -46,6 +46,8 @@ public:
 
    std::shared_ptr<WaveTrack> GetTrack() const { return mClickedTrack; }
 
+   void Enter() override;
+
    Result Click
       (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;
 

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

@@ -49,6 +49,10 @@ WaveTrackVZoomHandle::WaveTrackVZoomHandle
    : mZoomStart(y), mZoomEnd(y), mRect(rect)
    , mpTrack{ pTrack }
 {
+}
+
+void WaveTrackVZoomHandle::Enter()
+{
 #ifdef EXPERIMENTAL_TRACK_PANEL_HIGHLIGHTING
    mChangeHighlight = RefreshCode::RefreshCell;
 #endif

src/tracks/playabletrack/wavetrack/ui/WaveTrackVZoomHandle.h

@@ -38,6 +38,8 @@ public:
 
    std::shared_ptr<WaveTrack> GetTrack() const { return mpTrack.lock(); }
 
+   void Enter() override;
+
    Result Click
       (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;
 

src/tracks/ui/ButtonHandle.cpp

@@ -25,13 +25,17 @@ ButtonHandle::ButtonHandle
    : mpTrack{ pTrack }
    , mRect{ rect }
 {
-   mChangeHighlight = RefreshCode::RefreshCell;
 }
 
 ButtonHandle::~ButtonHandle()
 {
 }
 
+void ButtonHandle::Enter()
+{
+   mChangeHighlight = RefreshCode::RefreshCell;
+}
+
 UIHandle::Result ButtonHandle::Click
 (const TrackPanelMouseEvent &evt, AudacityProject *pProject)
 {

src/tracks/ui/ButtonHandle.h

@@ -42,6 +42,8 @@ protected:
    virtual Result CommitChanges
       (const wxMouseEvent &event, AudacityProject *pProject, wxWindow *pParent) = 0;
 
+   void Enter() override;
+
    Result Click
       (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;
 

src/tracks/ui/EnvelopeHandle.cpp

@@ -30,6 +30,10 @@ Paul Licameli split from TrackPanel.cpp
 EnvelopeHandle::EnvelopeHandle( Envelope *pEnvelope )
    : mEnvelope{ pEnvelope }
 {
+}
+
+void EnvelopeHandle::Enter()
+{
 #ifdef EXPERIMENTAL_TRACK_PANEL_HIGHLIGHTING
    mChangeHighlight = RefreshCode::RefreshCell;
 #endif

src/tracks/ui/EnvelopeHandle.h

@@ -56,6 +56,8 @@ public:
 
    Envelope *GetEnvelope() const { return mEnvelope; }
 
+   void Enter() override;
+
    Result Click
       (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;
 

src/tracks/ui/SliderHandle.cpp

@@ -21,6 +21,10 @@ SliderHandle::SliderHandle
    : mSliderFn{ sliderFn }
    , mRect{ rect }
    , mpTrack{ pTrack }
+{
+}
+
+void SliderHandle::Enter()
 {
    mChangeHighlight = RefreshCode::RefreshCell;
 }

src/tracks/ui/SliderHandle.h

@@ -47,6 +47,8 @@ protected:
    virtual Result CommitChanges
       (const wxMouseEvent &event, AudacityProject *pProject) = 0;
 
+   void Enter() override;
+
    Result Click
       (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;
 

src/tracks/ui/TimeShiftHandle.cpp

@@ -29,6 +29,10 @@ TimeShiftHandle::TimeShiftHandle
    : mCapturedTrack{ pTrack }
    , mGripHit{ gripHit }
 {
+}
+
+void TimeShiftHandle::Enter()
+{
 #ifdef EXPERIMENTAL_TRACK_PANEL_HIGHLIGHTING
    mChangeHighlight = RefreshCode::RefreshCell;
 #endif

src/tracks/ui/TimeShiftHandle.h

@@ -75,6 +75,8 @@ public:
 
    virtual ~TimeShiftHandle();
 
+   void Enter() override;
+
    Result Click
       (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;