Remove unnecessary parts of fix for bug 2501...

... Don't need to put the project in a strange state where Undo commands are
ignored until labels are de-selected

src/menus/EditMenus.cpp

@@ -183,13 +183,6 @@ void OnUndo(const CommandContext &context)
       return;
    }
 
-   for (auto lt : tracks.Selected< LabelTrack >()) {
-      auto &view = LabelTrackView::Get( *lt );
-      if (!view.Undo( project )) {
-         return;
-      }
-   }
-
    undoManager.Undo(
       [&]( const UndoStackElem &elem ){
          ProjectHistory::Get( project ).PopState( elem.state ); } );

src/tracks/labeltrack/ui/LabelTrackView.cpp

@@ -64,21 +64,6 @@ LabelTrackView::Index &LabelTrackView::Index::operator =(int index)
    return *this;
 }
 
-
-LabelTrackView::Index &LabelTrackView::Index::operator +(int index)
-{
-   mModified = false;
-   mIndex += index;
-   return *this;
-}
-
-LabelTrackView::Index &LabelTrackView::Index::operator -(int index)
-{
-   mModified = false;
-   mIndex -= index;
-   return *this;
-}
-
 LabelTrackView::Index &LabelTrackView::Index::operator ++()
 {
    mModified = false;
@@ -1019,22 +1004,6 @@ bool LabelTrackView::IsTextSelected( AudacityProject &project ) const
    return true;
 }
 
-bool LabelTrackView::Undo( AudacityProject &project )
-{
-   if (HasSelection( project )) {
-      const auto pTrack = FindLabelTrack();
-      const auto &mLabels = pTrack->GetLabels();
-      auto labelStruct = mLabels[mSelIndex];
-      auto &title = labelStruct.title;
-      if (title.size() == 0) {
-         return true;
-      }
-      return mSelIndex.IsModified();
-   }
-
-   return true;
-}
-
 /// Cut the selected text in the text box
 ///  @return true if text is selected in text box, false otherwise
 bool LabelTrackView::CutSelectedText( AudacityProject &project )

src/tracks/labeltrack/ui/LabelTrackView.h

@@ -112,8 +112,6 @@ public:
    int GetSelectedIndex( AudacityProject &project ) const;
    void SetSelectedIndex( int index );
 
-   bool Undo( AudacityProject &project );
-
    bool CutSelectedText( AudacityProject &project );
    bool CopySelectedText( AudacityProject &project );
    bool PasteSelectedText(
@@ -131,8 +129,6 @@ private:
       Index(int index);
       operator int() const;
       Index &operator =(int index);
-      Index &operator +(int index);
-      Index &operator -(int index);
       Index &operator ++();
       Index &operator --();
 
@@ -141,7 +137,6 @@ private:
 
    private:
       int mIndex;
-      int mFlag;
       bool mModified;
    };