Is, or is not, in-class initialization of static variables C++ 11 compliant?

Question

OS: Fedora 21

GCC Ver 4.9.2

Codeblocks Ver 10253 (compiler set to "have g++ follow C++ 11 ISO C++ language standards.")

Error: "Spreadsheet.h|34|error: ISO C++ forbids in-class initialization of non-const static member ‘Spreadsheet::sCounter’|"

EDIT: Please don't point me to work arounds. I already know them. I want to know if the book is wrong and in-class initialization of static variables is C++ 11 compliant or not.

This code is from Professional C++ by Gregoire and others. This is the first time GCC has not been able to compile C++ 11 code from this text.

The following code (see last line) results in the error:

/ Spreadsheet.h
#include "SpreadsheetCell.h"

class SpreadsheetApplication; // forward declaration

class Spreadsheet
{
   public:
     Spreadsheet(int inWidth, int inHeight,
           const SpreadsheetApplication& theApp);
     Spreadsheet(const Spreadsheet& src);
     ~Spreadsheet();
     Spreadsheet& operator=(const Spreadsheet& rhs);

     void setCellAt(int x, int y, const SpreadsheetCell& cell);
     SpreadsheetCell getCellAt(int x, int y);

     int getId() const;

  // Doesn't work in Microsoft Visual Studio 6
  static const int kMaxHeight = 100;
  static const int kMaxWidth = 100;

 protected:
     bool inRange(int val, int upper);
     void copyFrom(const Spreadsheet& src);

     int mWidth, mHeight;
     int mId;
     SpreadsheetCell** mCells;

     const SpreadsheetApplication& mTheApp;

     static int sCounter = 0;  // Produces Error 

};