TrackPanelCell hit tests can return multiple results...

.. though only the first is used yet

src/LabelTrack.h

@@ -125,7 +125,7 @@ class AUDACITY_DLL_API LabelTrack final : public Track
 
    virtual ~ LabelTrack();
 
-   UIHandlePtr DetailedHitTest
+   std::vector<UIHandlePtr> DetailedHitTest
       (const TrackPanelMouseState &state,
        const AudacityProject *pProject, int currentTool, bool bMultiTool)
       override;

src/NoteTrack.h

@@ -70,7 +70,7 @@ class AUDACITY_DLL_API NoteTrack final
    NoteTrack(const std::shared_ptr<DirManager> &projDirManager);
    virtual ~NoteTrack();
 
-   UIHandlePtr DetailedHitTest
+   std::vector<UIHandlePtr> DetailedHitTest
       (const TrackPanelMouseState &state,
        const AudacityProject *pProject, int currentTool, bool bMultiTool)
       override;

src/TimeTrack.h

@@ -51,7 +51,7 @@ class TimeTrack final : public Track {
    void Silence(double t0, double t1) override;
    void InsertSilence(double t, double len) override;
 
-   UIHandlePtr DetailedHitTest
+   std::vector<UIHandlePtr> DetailedHitTest
       (const TrackPanelMouseState &state,
        const AudacityProject *pProject, int currentTool, bool bMultiTool)
       override;

src/Track.h

@@ -136,14 +136,14 @@ class AUDACITY_DLL_API Track /* not final */
    // Cause certain overriding tool modes (Zoom; future ones?) to behave
    // uniformly in all tracks, disregarding track contents.
    // Do not further override this...
-   UIHandlePtr HitTest
+   std::vector<UIHandlePtr> HitTest
       (const TrackPanelMouseState &, const AudacityProject *pProject)
       final;
 
  public:
 
    // Rather override this for subclasses:
-   virtual UIHandlePtr DetailedHitTest
+   virtual std::vector<UIHandlePtr> DetailedHitTest
       (const TrackPanelMouseState &,
        const AudacityProject *pProject, int currentTool, bool bMultiTool)
       = 0;

src/TrackPanel.cpp

@@ -904,7 +904,10 @@ void TrackPanel::HandleMotion( const TrackPanelMouseState &tpmState )
 
       // Now do the
       // UIHANDLE HIT TEST !
-      handle = newCell->HitTest(tpmState, GetProject());
+      auto targets = newCell->HitTest(tpmState, GetProject());
+
+      // No use, yet, of any but the first target
+      handle = targets.empty() ? UIHandlePtr{} : targets[0];
 
       mLastCell = newCell;
       mLastHitTest = handle;

src/TrackPanelCell.h

@@ -25,6 +25,8 @@ class wxWindow;
 class UIHandle;
 using UIHandlePtr = std::shared_ptr<UIHandle>;
 
+#include <vector>
+
 // Abstract base class defining TrackPanel's access to specialist classes that
 // implement drawing and user interactions
 class AUDACITY_DLL_API TrackPanelCell /* not final */
@@ -32,12 +34,12 @@ class AUDACITY_DLL_API TrackPanelCell /* not final */
 public:
    virtual ~TrackPanelCell () = 0;
 
-   // Return null, or a pointer to an object that can be queried for a status
+   // Return pointers to objects that can be queried for a status
-   // bar message and cursor appropriate to the point, and that dispatches
+   // bar message and cursor appropriate to the point, and that dispatch
    // mouse button events.
    // The button-down state passed to the function is as it will be at click
    // time -- not necessarily as it is now.
-   virtual UIHandlePtr HitTest
+   virtual std::vector<UIHandlePtr> HitTest
       (const TrackPanelMouseState &state,
        const AudacityProject *pProject) = 0;
 

src/TrackPanelResizerCell.cpp

@@ -21,15 +21,16 @@ TrackPanelResizerCell::TrackPanelResizerCell( std::shared_ptr<Track> pTrack )
 : mpTrack{ pTrack }
 {}
 
-UIHandlePtr TrackPanelResizerCell::HitTest
+std::vector<UIHandlePtr> TrackPanelResizerCell::HitTest
 (const TrackPanelMouseState &st, const AudacityProject *pProject)
 {
+   std::vector<UIHandlePtr> results;
    auto pTrack = mpTrack.lock();
    if (pTrack) {
       auto result = std::make_shared<TrackPanelResizeHandle>(
          pTrack, st.state.m_y, pProject );
       result = AssignUIHandlePtr(mResizeHandle, result);
-      return result;
+      results.push_back(result);
    }
-   return {};
+   return results;
 }

src/TrackPanelResizerCell.h

@@ -24,7 +24,7 @@ public:
    explicit
    TrackPanelResizerCell( std::shared_ptr<Track> pTrack );
 
-   UIHandlePtr HitTest
+   std::vector<UIHandlePtr> HitTest
       (const TrackPanelMouseState &, const AudacityProject *) override;
 
    std::shared_ptr<Track> FindTrack() override { return mpTrack.lock(); };

src/WaveTrack.h

@@ -107,7 +107,7 @@ class AUDACITY_DLL_API WaveTrack final : public PlayableTrack {
 
    virtual ~WaveTrack();
 
-   UIHandlePtr DetailedHitTest
+   std::vector<UIHandlePtr> DetailedHitTest
       (const TrackPanelMouseState &state,
        const AudacityProject *pProject, int currentTool, bool bMultiTool)
       override;

src/tracks/labeltrack/ui/LabelTrackControls.cpp

@@ -26,7 +26,7 @@ LabelTrackControls::~LabelTrackControls()
 {
 }
 
-UIHandlePtr LabelTrackControls::HitTest
+std::vector<UIHandlePtr> LabelTrackControls::HitTest
 (const TrackPanelMouseState & state,
  const AudacityProject *pProject)
 {

src/tracks/labeltrack/ui/LabelTrackControls.h

@@ -24,7 +24,7 @@ public:
       : TrackControls( pTrack ) {}
    ~LabelTrackControls();
 
-   UIHandlePtr HitTest
+   std::vector<UIHandlePtr> HitTest
       (const TrackPanelMouseState &state,
        const AudacityProject *pProject) override;
 

src/tracks/labeltrack/ui/LabelTrackUI.cpp

@@ -21,23 +21,25 @@ Paul Licameli split from TrackPanel.cpp
 #include "../../../Project.h"
 #include "../../../TrackPanelMouseEvent.h"
 
-UIHandlePtr LabelTrack::DetailedHitTest
+std::vector<UIHandlePtr> LabelTrack::DetailedHitTest
 (const TrackPanelMouseState &st,
  const AudacityProject *pProject, int, bool)
 {
+   UIHandlePtr result;
+   std::vector<UIHandlePtr> results;
    const wxMouseState &state = st.state;
 
-   // Try label movement handles first
-   UIHandlePtr result;
    result = LabelGlyphHandle::HitTest(
       mGlyphHandle, state, Pointer<LabelTrack>(this), st.rect);
+   if (result)
+      results.push_back(result);
 
-   if ( !result )
-      // Missed glyph, try text box
    result = LabelTextHandle::HitTest(
       mTextHandle, state, Pointer<LabelTrack>(this));
+   if (result)
+      results.push_back(result);
 
-   return result;
+   return results;
 }
 
 std::shared_ptr<TrackControls> LabelTrack::GetControls()

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

@@ -30,15 +30,17 @@ NoteTrackControls::~NoteTrackControls()
 {
 }
 
-UIHandlePtr NoteTrackControls::HitTest
+std::vector<UIHandlePtr> NoteTrackControls::HitTest
 (const TrackPanelMouseState & st,
  const AudacityProject *pProject)
 {
+   // Hits are mutually exclusive, results single
+   std::vector<UIHandlePtr> results;
    const wxMouseState &state = st.state;
    const wxRect &rect = st.rect;
    if (state.ButtonIsDown(wxMOUSE_BTN_ANY)) {
       auto track = std::static_pointer_cast<NoteTrack>(FindTrack());
-      if (track && track->GetKind() == Track::Note) {
+      auto result = [&]{
          UIHandlePtr result;
          if (NULL != (result = MuteButtonHandle::HitTest(
             mMuteHandle, state, rect, pProject, track)))
@@ -55,6 +57,10 @@ UIHandlePtr NoteTrackControls::HitTest
             mClickHandle, state, rect, track)))
             return result;
 #endif
+      }();
+      if (result) {
+         results.push_back(result);
+         return results;
       }
    }
 

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

@@ -35,7 +35,7 @@ public:
       : TrackControls( pTrack ) {}
    ~NoteTrackControls();
 
-   UIHandlePtr HitTest
+   std::vector<UIHandlePtr> HitTest
       (const TrackPanelMouseState &state,
        const AudacityProject *pProject) override;
 

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

@@ -22,18 +22,21 @@ Paul Licameli split from TrackPanel.cpp
 #include "../../../ui/SelectHandle.h"
 #include "StretchHandle.h"
 
-UIHandlePtr NoteTrack::DetailedHitTest
+std::vector<UIHandlePtr> NoteTrack::DetailedHitTest
 (const TrackPanelMouseState &state,
  const AudacityProject *pProject, int, bool )
 {
    // Eligible for stretch?
    UIHandlePtr result;
+   std::vector<UIHandlePtr> results;
 #ifdef USE_MIDI
    result = StretchHandle::HitTest(
       mStretchHandle, state, pProject, Pointer<NoteTrack>(this) );
+   if (result)
+      results.push_back(result);
 #endif
 
-   return result;
+   return results;
 }
 
 std::shared_ptr<TrackControls> NoteTrack::GetControls()

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

@@ -27,14 +27,22 @@ NoteTrackVRulerControls::~NoteTrackVRulerControls()
 {
 }
 
-UIHandlePtr NoteTrackVRulerControls::HitTest
+std::vector<UIHandlePtr> NoteTrackVRulerControls::HitTest
 (const TrackPanelMouseState &st,
  const AudacityProject *pProject)
 {
+   std::vector<UIHandlePtr> results;
    UIHandlePtr result;
    auto track = std::static_pointer_cast<NoteTrack>(FindTrack());
-   return NoteTrackVZoomHandle::HitTest(
+   result = NoteTrackVZoomHandle::HitTest(
       mVZoomHandle, st.state, track, st.rect);
+   if (result)
+      results.push_back(result);
+
+   auto more = TrackVRulerControls::HitTest(st, pProject);
+   std::copy(more.begin(), more.end(), std::back_inserter(results));
+
+   return results;
 }
 
 unsigned NoteTrackVRulerControls::HandleWheelRotation

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

@@ -26,7 +26,7 @@ public:
       : TrackVRulerControls( pTrack ) {}
    ~NoteTrackVRulerControls();
 
-   UIHandlePtr HitTest
+   std::vector<UIHandlePtr> HitTest
       (const TrackPanelMouseState &state,
        const AudacityProject *pProject) override;
 

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

@@ -53,15 +53,17 @@ WaveTrackControls::~WaveTrackControls()
 }
 
 
-UIHandlePtr WaveTrackControls::HitTest
+std::vector<UIHandlePtr> WaveTrackControls::HitTest
 (const TrackPanelMouseState & st,
  const AudacityProject *pProject)
 {
+   // Hits are mutually exclusive, results single
    const wxMouseState &state = st.state;
    const wxRect &rect = st.rect;
    if (state.ButtonIsDown(wxMOUSE_BTN_LEFT)) {
       auto track = FindTrack();
-      if (track && track->GetKind() == Track::Wave) {
+      std::vector<UIHandlePtr> results;
+      auto result = [&]{
          UIHandlePtr result;
          if (NULL != (result = MuteButtonHandle::HitTest(
             mMuteHandle, state, rect, pProject, track)))
@@ -78,6 +80,10 @@ UIHandlePtr WaveTrackControls::HitTest
          if (NULL != (result = PanSliderHandle::HitTest(
             mPanHandle, state, rect, track)))
             return result;
+      }();
+      if (result) {
+         results.push_back(result);
+         return results;
       }
    }
 

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

@@ -29,7 +29,7 @@ public:
       : TrackControls( pTrack ) {}
    ~WaveTrackControls();
 
-   UIHandlePtr HitTest
+   std::vector<UIHandlePtr> HitTest
       (const TrackPanelMouseState &state,
        const AudacityProject *pProject) override;
 

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

@@ -23,7 +23,7 @@ Paul Licameli split from TrackPanel.cpp
 #include "SampleHandle.h"
 #include "../../../ui/TimeShiftHandle.h"
 
-UIHandlePtr WaveTrack::DetailedHitTest
+std::vector<UIHandlePtr> WaveTrack::DetailedHitTest
 (const TrackPanelMouseState &st,
  const AudacityProject *pProject, int currentTool, bool bMultiTool)
 {
@@ -32,15 +32,20 @@ UIHandlePtr WaveTrack::DetailedHitTest
    // If that toolbar were eliminated, this could simplify to a sequence of
    // hit test routines describable by a table.
 
-   const auto wavetrack = static_cast<WaveTrack*>(st.pCell.get());
+   UIHandlePtr result;
-   bool isWaveform = (wavetrack->GetDisplay() == WaveTrack::Waveform);
+   std::vector<UIHandlePtr> results;
+   bool isWaveform = (GetDisplay() == WaveTrack::Waveform);
 
-   if (bMultiTool && st.state.CmdDown())
+   if (bMultiTool && st.state.CmdDown()) {
       // Ctrl modifier key in multi-tool overrides everything else
       // (But this does not do the time shift constrained to the vertical only,
       //  which is what happens when you hold Ctrl in the Time Shift tool mode)
-      return TimeShiftHandle::HitAnywhere(
+      result = TimeShiftHandle::HitAnywhere(
          mTimeShiftHandle, Pointer(this), false);
+      if (result)
+         results.push_back(result);
+      return results;
+   }
 
    // Some special targets are not drawn in spectrogram,
    // so don't hit them in such views.
@@ -50,8 +55,8 @@ UIHandlePtr WaveTrack::DetailedHitTest
          mCutlineHandle, st.state, st.rect,
          pProject, Pointer<WaveTrack>(this))))
          // This overriding test applies in all tools
-         return result;
+         results.push_back(result);
-      else if (bMultiTool) {
+      if (bMultiTool) {
          // Conditional hit tests
          // If Tools toolbar were eliminated, we would keep these
          // The priority of these, in case more than one might apply at one
@@ -59,35 +64,39 @@ UIHandlePtr WaveTrack::DetailedHitTest
          if (NULL != (result = EnvelopeHandle::WaveTrackHitTest(
             mEnvelopeHandle, st.state, st.rect,
             pProject, Pointer<WaveTrack>(this))))
-            ;
+            results.push_back(result);
-         else if (NULL != (result = TimeShiftHandle::HitTest(
+         if (NULL != (result = TimeShiftHandle::HitTest(
             mTimeShiftHandle, st.state, st.rect, Pointer(this))))
             // This is the hit test on the "grips" drawn left and
             // right in Multi only
-            ;
+            results.push_back(result);
-         else if (NULL != (result = SampleHandle::HitTest(
+         if (NULL != (result = SampleHandle::HitTest(
             mSampleHandle, st.state, st.rect,
             pProject, Pointer<WaveTrack>(this))))
-            ;
+            results.push_back(result);
-         return result;
       }
-      else switch ( currentTool ) {
+      else {
+         switch ( currentTool ) {
                // Unconditional hits appropriate to the tool
                // If tools toolbar were eliminated, we would eliminate these
             case envelopeTool: {
                auto envelope = GetEnvelopeAtX( st.state.m_x );
-            return EnvelopeHandle::HitAnywhere(
+               result = EnvelopeHandle::HitAnywhere(
                   mEnvelopeHandle, envelope);
+               break;
             }
             case drawTool:
-            return SampleHandle::HitAnywhere(
+               result = SampleHandle::HitAnywhere(
                   mSampleHandle, st.state, Pointer<WaveTrack>(this));
             default:
                break;
          }
+         if (result)
+            results.push_back(result);
+      }
    }
 
-   return {};
+   return results;
 }
 
 std::shared_ptr<TrackControls> WaveTrack::GetControls()

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

@@ -26,18 +26,23 @@ WaveTrackVRulerControls::~WaveTrackVRulerControls()
 {
 }
 
-UIHandlePtr WaveTrackVRulerControls::HitTest
+std::vector<UIHandlePtr> WaveTrackVRulerControls::HitTest
 (const TrackPanelMouseState &st,
- const AudacityProject *)
+ const AudacityProject *pProject)
 {
+   std::vector<UIHandlePtr> results;
    auto pTrack = Track::Pointer<WaveTrack>( FindTrack().get() );
    if (pTrack) {
       auto result = std::make_shared<WaveTrackVZoomHandle>(
          pTrack, st.rect, st.state.m_y );
       result = AssignUIHandlePtr(mVZoomHandle, result);
-      return result;
+      results.push_back(result);
    }
-   return {};
+
+   auto more = TrackVRulerControls::HitTest(st, pProject);
+   std::copy(more.begin(), more.end(), std::back_inserter(results));
+
+   return results;
 }
 
 unsigned WaveTrackVRulerControls::HandleWheelRotation

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

@@ -26,7 +26,7 @@ public:
       : TrackVRulerControls( pTrack ) {}
    ~WaveTrackVRulerControls();
 
-   UIHandlePtr HitTest
+   std::vector<UIHandlePtr> HitTest
       (const TrackPanelMouseState &state,
        const AudacityProject *) override;
 

src/tracks/timetrack/ui/TimeTrackControls.cpp

@@ -21,7 +21,7 @@ TimeTrackControls::~TimeTrackControls()
 {
 }
 
-UIHandlePtr TimeTrackControls::HitTest
+std::vector<UIHandlePtr> TimeTrackControls::HitTest
 (const TrackPanelMouseState & state,
  const AudacityProject *pProject)
 {

src/tracks/timetrack/ui/TimeTrackControls.h

@@ -24,7 +24,7 @@ public:
       : TrackControls( pTrack ) {}
    ~TimeTrackControls();
 
-   UIHandlePtr HitTest
+   std::vector<UIHandlePtr> HitTest
       (const TrackPanelMouseState &state,
        const AudacityProject *pProject) override;
 

src/tracks/timetrack/ui/TimeTrackUI.cpp

@@ -18,12 +18,16 @@ Paul Licameli split from TrackPanel.cpp
 
 #include "../../ui/EnvelopeHandle.h"
 
-UIHandlePtr TimeTrack::DetailedHitTest
+std::vector<UIHandlePtr> TimeTrack::DetailedHitTest
 (const TrackPanelMouseState &st,
  const AudacityProject *pProject, int, bool)
 {
-   return EnvelopeHandle::TimeTrackHitTest
+   std::vector<UIHandlePtr> results;
+   auto result = EnvelopeHandle::TimeTrackHitTest
       ( mEnvelopeHandle, st.state, st.rect, pProject, Pointer<TimeTrack>(this) );
+   if (result)
+      results.push_back(result);
+   return results;
 }
 
 std::shared_ptr<TrackControls> TimeTrack::GetControls()

src/tracks/ui/BackgroundCell.cpp

@@ -79,14 +79,16 @@ BackgroundCell::~BackgroundCell()
 {
 }
 
-UIHandlePtr BackgroundCell::HitTest
+std::vector<UIHandlePtr> BackgroundCell::HitTest
 (const TrackPanelMouseState &,
  const AudacityProject *)
 {
+   std::vector<UIHandlePtr> results;
    auto result = mHandle.lock();
    if (!result)
       result = std::make_shared<BackgroundHandle>();
-   return result;
+   results.push_back(result);
+   return results;
 }
 
 std::shared_ptr<Track> BackgroundCell::FindTrack()

src/tracks/ui/BackgroundCell.h

@@ -29,7 +29,7 @@ public:
    virtual ~BackgroundCell();
 
 protected:
-   UIHandlePtr HitTest
+   std::vector<UIHandlePtr> HitTest
       (const TrackPanelMouseState &state,
        const AudacityProject *) override;
 

src/tracks/ui/TrackControls.cpp

@@ -37,13 +37,16 @@ std::shared_ptr<Track> TrackControls::FindTrack()
    return mwTrack.lock();
 }
 
-UIHandlePtr TrackControls::HitTest
+std::vector<UIHandlePtr> TrackControls::HitTest
 (const TrackPanelMouseState &st,
  const AudacityProject *project)
 {
+   // Hits are mutually exclusive, results single
+
    const wxMouseState &state = st.state;
    const wxRect &rect = st.rect;
    UIHandlePtr result;
+   std::vector<UIHandlePtr> results;
 
    auto pTrack = FindTrack();
    // shared pointer to this:
@@ -51,18 +54,23 @@ UIHandlePtr TrackControls::HitTest
 
    if (NULL != (result = CloseButtonHandle::HitTest(
       mCloseHandle, state, rect, this)))
-      return result;
+      results.push_back(result);
 
    if (NULL != (result = MenuButtonHandle::HitTest(
       mMenuHandle, state, rect, sThis)))
-      return result;
+      results.push_back(result);
 
    if (NULL != (result = MinimizeButtonHandle::HitTest(
       mMinimizeHandle, state, rect, this)))
-      return result;
+      results.push_back(result);
 
-   return TrackSelectHandle::HitAnywhere(
+   if (results.empty()) {
-      mSelectHandle, pTrack);
+      if (NULL != (result = TrackSelectHandle::HitAnywhere(
+         mSelectHandle, pTrack)))
+         results.push_back(result);
+   }
+
+   return results;
 }
 
 enum

src/tracks/ui/TrackControls.h

@@ -48,7 +48,7 @@ public:
 protected:
    // An override is supplied for derived classes to call through but it is
    // still marked pure virtual
-   virtual UIHandlePtr HitTest
+   virtual std::vector<UIHandlePtr> HitTest
       (const TrackPanelMouseState &state,
        const AudacityProject *) override = 0;
 

src/tracks/ui/TrackUI.cpp

@@ -25,44 +25,57 @@ Paul Licameli split from TrackPanel.cpp
 #include "../../TrackPanelResizerCell.h"
 #include "BackgroundCell.h"
 
-UIHandlePtr Track::HitTest
+std::vector<UIHandlePtr> Track::HitTest
 (const TrackPanelMouseState &st,
  const AudacityProject *pProject)
 {
+   UIHandlePtr result;
+   std::vector<UIHandlePtr> results;
    const ToolsToolBar * pTtb = pProject->GetToolsToolBar();
    const bool isMultiTool = pTtb->IsDown(multiTool);
    const auto currentTool = pTtb->GetCurrentTool();
 
-   if ( !isMultiTool && currentTool == zoomTool )
+   if ( !isMultiTool && currentTool == zoomTool ) {
       // Zoom tool is a non-selecting tool that takes precedence in all tracks
       // over all other tools, no matter what detail you point at.
-      return ZoomHandle::HitAnywhere(
+      result = ZoomHandle::HitAnywhere(
          pProject->GetBackgroundCell()->mZoomHandle);
+      results.push_back(result);
+      return results;
+   }
 
    // In other tools, let subclasses determine detailed hits.
-   auto result =
+   results =
       DetailedHitTest( st, pProject, currentTool, isMultiTool );
 
-   // If there is no detailed hit for the subclass, there are still some
+   // There are still some general cases.
-   // general cases.
 
    // Sliding applies in more than one track type.
-   if ( !result && !isMultiTool && currentTool == slideTool )
+   if ( !isMultiTool && currentTool == slideTool ) {
       result = TimeShiftHandle::HitAnywhere(
          mTimeShiftHandle, Pointer(this), false);
+      if (result)
+         results.push_back(result);
+   }
 
    // Let the multi-tool right-click handler apply only in default of all
    // other detailed hits.
-   if ( !result && isMultiTool )
+   if ( isMultiTool ) {
       result = ZoomHandle::HitTest(
          pProject->GetBackgroundCell()->mZoomHandle, st.state);
+      if (result)
+         results.push_back(result);
+   }
 
    // Finally, default of all is adjustment of the selection box.
-   if ( !result && ( isMultiTool || currentTool == selectTool) )
+   if ( isMultiTool || currentTool == selectTool ) {
       result = SelectHandle::HitTest(
          mSelectHandle, st, pProject, Pointer(this));
+      if (result)
+         results.push_back(result);
+   }
 
-   return result;
+   return results;
 }
 
 std::shared_ptr<TrackPanelCell> Track::GetTrackControl()

src/tracks/ui/TrackVRulerControls.cpp

@@ -32,10 +32,10 @@ std::shared_ptr<Track> TrackVRulerControls::FindTrack()
    return mwTrack.lock();
 }
 
-UIHandlePtr TrackVRulerControls::HitTest
+std::vector<UIHandlePtr> TrackVRulerControls::HitTest
 (const TrackPanelMouseState &, const AudacityProject *)
 {
-   return {};
+   return std::vector<UIHandlePtr>{};
 }
 
 void TrackVRulerControls::DrawZooming

src/tracks/ui/TrackVRulerControls.h

@@ -28,7 +28,7 @@ public:
    std::shared_ptr<Track> FindTrack() override;
 
    // Define a default hit test method, just for message and cursor
-   UIHandlePtr HitTest
+   std::vector<UIHandlePtr> HitTest
       (const TrackPanelMouseState &state,
        const AudacityProject *pProject) override;