MFC-IsIconic判断窗口是否最小化

HWND hWnd = NULL;
UINT func1(LPVOID pParam)   //线程函数
{
    BOOL bb;

    for (int i = 0; i < 1000; i++) {
        bb = IsIconic(hWnd);//判断窗口是否最小化
        /*
        参数1：HWND hWnd  窗口句柄
        返回值：已经最小化返回TRUE,
                非最小化返回FALSE
        */
        CString str;
        str.Format(_T("bb=%d"), bb);
        ::OutputDebugString(str);
        Sleep(1000);
    }

    return 0;
}


void CssDlg::OnBnClickedButton1()
{
    
    hWnd = GetSafeHwnd();
    CWinThread* pp = AfxBeginThread(func1, LPVOID(456), 0, 0, 0, NULL);

}