weaken dependency of TrackPanel.cpp on LabelTrack.h, a bit

src/LabelTrack.cpp

@@ -1130,6 +1130,17 @@ double LabelTrack::GetEndTime() const
    return end;
 }
 
+Track *LabelTrack::Duplicate()
+{
+   return new LabelTrack(*this);
+}
+
+void LabelTrack::SetSelected(bool s)
+{
+   Track::SetSelected(s);
+   if (!s)
+      Unselect();
+}
 
 /// OverGlyph returns 0 if not over a glyph,
 /// 1 if over the left-hand glyph, and

src/LabelTrack.h

@@ -139,7 +139,9 @@ class AUDACITY_DLL_API LabelTrack : public Track
    virtual double GetStartTime() const;
    virtual double GetEndTime() const;
 
-   virtual Track *Duplicate() { return new LabelTrack(*this); }
+   virtual Track *Duplicate();
+
+   virtual void SetSelected(bool s);
 
    virtual bool HandleXMLTag(const wxChar *tag, const wxChar **attrs);
    virtual XMLTagHandler *HandleXMLChild(const wxChar *tag);

src/Track.cpp

@@ -112,6 +112,11 @@ void Track::Init(const Track &orig)
 #endif
 }
 
+void Track::SetSelected(bool s)
+{
+   mSelected = s;
+}
+
 void Track::Merge(const Track &orig)
 {
    mSelected = orig.mSelected;

src/Track.h

@@ -159,7 +159,7 @@ class AUDACITY_DLL_API Track: public XMLTagHandler
    bool GetLinked  () const { return mLinked;   }
    bool GetSolo    () const { return mSolo;     }
 
-   void SetSelected(bool s) { mSelected = s; }
+   virtual void SetSelected(bool s);
    void SetMute    (bool m) { mMute     = m; }
    void SetLinked  (bool l);
    void SetSolo    (bool s) { mSolo     = s; }

src/TrackPanel.cpp

@@ -996,8 +996,6 @@ void TrackPanel::SelectNone()
    Track *t = iter.First();
    while (t) {
       t->SetSelected(false);
-      if (t->GetKind() == Track::Label)
-         ((LabelTrack *) t)->Unselect();
       t = iter.Next();
    }
 }