线程同步里的AfxMessageBox函数问题！

// mmnDlg.cpp : implementation file

//



#include "stdafx.h"



#include <windowsx.h>

#include <process.h>

#include "mmn.h"

#include "mmnDlg.h"



#ifdef _DEBUG

#define new DEBUG_NEW

#undef THIS_FILE

static char THIS_FILE[] = __FILE__;

#endif



/////////////////////////////////////////////////////////////////////////////

// CAboutDlg dialog used for App About



HANDLE g_hevtRequestSubmitted;

HANDLE g_hevtResultReturned;

CString SharedString;





class CAboutDlg : public CDialog

{

public:

	CAboutDlg();



// Dialog Data

	//{{AFX_DATA(CAboutDlg)

	enum { IDD = IDD_ABOUTBOX };

	//}}AFX_DATA



	// ClassWizard generated virtual function overrides

	//{{AFX_VIRTUAL(CAboutDlg)

	protected:

	virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support

	//}}AFX_VIRTUAL



// Implementation

protected:

	//{{AFX_MSG(CAboutDlg)

	//}}AFX_MSG

	DECLARE_MESSAGE_MAP()

};



CAboutDlg::CAboutDlg() : CDialog(CAboutDlg::IDD)

{

	//{{AFX_DATA_INIT(CAboutDlg)

	//}}AFX_DATA_INIT

}



void CAboutDlg::DoDataExchange(CDataExchange* pDX)

{

	CDialog::DoDataExchange(pDX);

	//{{AFX_DATA_MAP(CAboutDlg)

	//}}AFX_DATA_MAP

}



BEGIN_MESSAGE_MAP(CAboutDlg, CDialog)

	//{{AFX_MSG_MAP(CAboutDlg)

		// No message handlers

	//}}AFX_MSG_MAP

END_MESSAGE_MAP()



/////////////////////////////////////////////////////////////////////////////

// CMmnDlg dialog



UINT _stdcall Func2(void *data)

{

	while(1)

	{

		WaitForSingleObject(g_hevtRequestSubmitted, INFINITE);

		SharedString += "kkk215215";

		AfxMessageBox(SharedString);

		MessageBox(NULL, "HAHA", "BAD", MB_OK);

		SetEvent(g_hevtResultReturned);

	}

	return 0;

}



CMmnDlg::CMmnDlg(CWnd* pParent /*=NULL*/)

	: CDialog(CMmnDlg::IDD, pParent)

{

	//{{AFX_DATA_INIT(CMmnDlg)

		// NOTE: the ClassWizard will add member initialization here

	//}}AFX_DATA_INIT

	// Note that LoadIcon does not require a subsequent DestroyIcon in Win32

	m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME);

	ThreadHandle1 = 0;

	ThreadHandle2 = 0;

}



void CMmnDlg::DoDataExchange(CDataExchange* pDX)

{

	CDialog::DoDataExchange(pDX);

	//{{AFX_DATA_MAP(CMmnDlg)

		// NOTE: the ClassWizard will add DDX and DDV calls here

	//}}AFX_DATA_MAP

}



BEGIN_MESSAGE_MAP(CMmnDlg, CDialog)

	//{{AFX_MSG_MAP(CMmnDlg)

	ON_WM_SYSCOMMAND()

	ON_WM_PAINT()

	ON_WM_QUERYDRAGICON()

	ON_BN_CLICKED(IDC_OK, OnOk)

	ON_BN_CLICKED(IDC_CANCEL, OnCancel)

	//}}AFX_MSG_MAP

END_MESSAGE_MAP()



/////////////////////////////////////////////////////////////////////////////

// CMmnDlg message handlers



BOOL CMmnDlg::OnInitDialog()

{

	CDialog::OnInitDialog();



	// Add "About..." menu item to system menu.



	// IDM_ABOUTBOX must be in the system command range.

	ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);

	ASSERT(IDM_ABOUTBOX < 0xF000);



	CMenu* pSysMenu = GetSystemMenu(FALSE);

	if (pSysMenu != NULL)

	{

		CString strAboutMenu;

		strAboutMenu.LoadString(IDS_ABOUTBOX);

		if (!strAboutMenu.IsEmpty())

		{

			pSysMenu->AppendMenu(MF_SEPARATOR);

			pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);

		}

	}



	// Set the icon for this dialog.  The framework does this automatically

	//  when the application's main window is not a dialog

	SetIcon(m_hIcon, TRUE);			// Set big icon

	SetIcon(m_hIcon, FALSE);		// Set small icon

	

	// TODO: Add extra initialization here

	UINT Fun1Code = 0, Fun2Code = 0;



	g_hevtRequestSubmitted = CreateEvent(NULL, FALSE, FALSE, NULL);

	g_hevtResultReturned   = CreateEvent(NULL, FALSE, FALSE, NULL);

	SharedString = "M2M";



	ThreadHandle2 = _beginthreadex(NULL, 0, Func2, NULL, 0, &Fun2Code);

	return TRUE;  // return TRUE  unless you set the focus to a control

}



void CMmnDlg::OnSysCommand(UINT nID, LPARAM lParam)

{

	if ((nID & 0xFFF0) == IDM_ABOUTBOX)

	{

		CAboutDlg dlgAbout;

		dlgAbout.DoModal();

	}

	else

	{

		CDialog::OnSysCommand(nID, lParam);

	}

}



// If you add a minimize button to your dialog, you will need the code below

//  to draw the icon.  For MFC applications using the document/view model,

//  this is automatically done for you by the framework.



void CMmnDlg::OnPaint() 

{

	if (IsIconic())

	{

		CPaintDC dc(this); // device context for painting



		SendMessage(WM_ICONERASEBKGND, (WPARAM) dc.GetSafeHdc(), 0);



		// Center icon in client rectangle

		int cxIcon = GetSystemMetrics(SM_CXICON);

		int cyIcon = GetSystemMetrics(SM_CYICON);

		CRect rect;

		GetClientRect(&rect);

		int x = (rect.Width() - cxIcon + 1) / 2;

		int y = (rect.Height() - cyIcon + 1) / 2;



		// Draw the icon

		dc.DrawIcon(x, y, m_hIcon);

	}

	else

	{

		CDialog::OnPaint();

	}

}



// The system calls this to obtain the cursor to display while the user drags

//  the minimized window.

HCURSOR CMmnDlg::OnQueryDragIcon()

{

	return (HCURSOR) m_hIcon;

}



void CMmnDlg::OnOk()

{

	// TODO: Add your control notification handler code here

	GetDlgItemText(IDC_EDIT1, SharedString);

	AfxMessageBox(SharedString);

	SetEvent(g_hevtRequestSubmitted);

	WaitForSingleObject(g_hevtResultReturned, INFINITE);

	AfxMessageBox(SharedString);

}



void CMmnDlg::OnCancel() 

{

	// TODO: Add your control notification handler code here

	CDialog::OnCancel();

}

这是一个线程同步的测试例子。很奇怪，在线程里，我调用AfxMessageBox()就不行，卡在那。DEBUG也跟不进去，并且没有返回值；但我调用MessageBox()就没有问题。上面标出来的两行代码。
高手帮帮忙哈！