Q_DECLARE_OPERATORS_FOR_FLAGS causes breakage in other flags, example source provided

When I declare operators for some of my custom flags, it causes some of the default flags to lose their operators. Below is an example that reproduces the issue (Qt 4.6/4.7).

Not sure if I've simply missed some caveat and, of course, in my actual app the MainWindow and Foo classes are in separate files as is the main().

Code:

#include <QList>
#include <QSet>
#include <iostream>
#include <cstdlib>
#include <ctime>
#include <QObject>
#include <QDockWidget>
#include <QMainWindow>
 
using namespace std;
 
namespace kex
{
  class Foo
  {
    Q_FLAGS(NType NTypes)
 
  public:
    enum NType {
      TypeOne = 0x1,
      TypeTwo = 0x2,
    };
    Q_DECLARE_FLAGS(NTypes, NType)
 
    void flagsFunc(NTypes nt)
    {
 
    }
  };
 
  Q_DECLARE_OPERATORS_FOR_FLAGS(Foo::NTypes)
 
    class MyMainWindow : public QMainWindow
    {
    public:
      MyMainWindow(QWidget *parent = 0) : QMainWindow(parent) {
        /*
temp.cpp: In constructor 'kex::MyMainWindow::MyMainWindow(QWidget*)':
temp.cpp:38: error: conversion from 'int' to 'Qt::DockWidgetAreas' is ambiguous
/Library/Frameworks/QtCore.framework/Headers/qglobal.h:2169: note: candidates are: QFlags<Enum>::QFlags(void**) [with Enum = Qt::DockWidgetArea] <near match>
/Library/Frameworks/QtCore.framework/Headers/qglobal.h:2168: note:                 QFlags<Enum>::QFlags(Enum) [with Enum = Qt::DockWidgetArea] <near match>
        */
        _dock.setAllowedAreas(Qt::LeftDockWidgetArea | 
          Qt::RightDockWidgetArea);
      }
 
    private:
      QDockWidget _dock;
    };
 
};
 
int main ()
{
  kex::Foo foo;
  foo.flagsFunc(kex::Foo::TypeOne | kex::Foo::TypeTwo);
  return 0