确保当前只有一个窗口进程

HANDLE hMutex = ::CreateMutex(NULL, FALSE, _T("MUTEX_WINDOW"));
HWND hMainWnd = NULL;
DWORD dwErrCode =  GetLastError() ;
if (NULL != hMutex && ERROR_ALREADY_EXISTS == dwErrCode)
{
hMainWnd = ::FindWindow(NULL,TEXT("窗口标题"));
if (hMainWnd)
{
::ShowWindow(hMainWnd, SW_SHOWNORMAL);
::SetForegroundWindow(hMainWnd);
}
return TRUE;
}
else if (NULL == hMutex)
{
return FALSE;
}