Modal Process

I have 2 applications. Say App1 and App2. Both are MFC dialog based applications. App1 invokes App2 using ShowModal(). Now I want App1 to wait until App2 is finished. This can be accomplished by MsgWaitForMultipleObjects(). Here I if I recieve WM_PAINT message for App1 then I allow it to recieve to App1. Any other i/p has to be removed and App2 has to have focus.

My requirement is if the user tries to do anything(mouse click, ALT+TAB, keydown) with App1 when App2 is open. I always want App2 to have focus.
I tried catching all the messages (but it flickers and its not the right solution). I tried catching specific messages but no luck. Anyidea how to achieve this?

DWORD dwID = 0;
static WNDPROC pWndProc = NULL;

static LRESULT CALLBACK InvokeWindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch (msg)
    {
      case WM_ACTIVATE:case WM_ACTIVATEAPP: case WM_LBUTTONUP: case WM_RBUTTONUP:
      case WM_NOTIFY:
            EnumThreadWindows(dwID, ModalEnumProc, 0);        
        break;
    }

    return CallWindowProc(pWndProc, hwnd, msg, wParam, lParam);
}

//Pass the full path of the .exe file. e.g "C:\App2.exe"
BOOL ShowModal(IN CString PcstrPath)
{
      BOOL fRetVal = FALSE;
      HANDLE hWait[2] = {NULL, NULL};

      do
      {
            if(PcstrPath.IsEmpty())//Cannot be empty
                  break;

            //Get the startup info
            STARTUPINFO sStartupInfo;
            ZeroMemory((void*)&sStartupInfo, sizeof(STARTUPINFO));
            sStartupInfo.cb = sizeof(STARTUPINFO);
            GetStartupInfo(&sStartupInfo);

            PROCESS_INFORMATION sProcessInfo;
            ZeroMemory((void*)&sProcessInfo, sizeof(PROCESS_INFORMATION));

            //Create the process
            if(!(fRetVal = CreateProcess(NULL, PcstrPath.GetBuffer(PcstrPath.GetLength()),
                  NULL, NULL, FALSE, 0, NULL, NULL, &sStartupInfo, &sProcessInfo)))
            {
                  break;
            }

            pWndProc = (WNDPROC)::SetWindowLong(AfxGetMainWnd()->m_hWnd,
                             GWL_WNDPROC, (LONG)&InvokeWindowProc);

            DWORD dwResult = 0;
            MSG msg;

            //Create the event so that we can break from the while loop in case we
            //recieve WM_QUIT, WM_QUERYENDSESSION or WM_CLOSE
            hWait[0] = CreateEvent(NULL, FALSE, FALSE, NULL);

            //Wait for the process to finish
            hWait[1] = sProcessInfo.hProcess;
            dwID = sProcessInfo.dwThreadId;

            //The message loop lasts until the other exe closes
            while(1)
            {
                  //Read all of the messages in this loop, first since MsgWaitForMultipleObjects
                  //will check the time and wait hence these messages might not be removed.
                  //Remove each message as we read it.
                  while(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
                  {
                        //Quit message, exit. Cannot be
                        if(WM_QUIT == msg.message || WM_CLOSE == msg.message ||
                              WM_QUERYENDSESSION == msg.message)  
                        {
                              SetEvent(hWait[0]);
                              break;
                        }
                        
                        
                        //Handle these messages to set focus to spawned application
                        switch(msg.message)
                        {
                        case WM_PAINT://Dispatch only WM_PAINT message
                              DispatchMessage(&msg); //Let it paint the window
                              break;
                        default:
                              break;
                        }
                  }//End of while message loop

                  //Wait for all messages sent or posted to this queue
                  //or for one of the passed handles be set to signaled.
                  dwResult = MsgWaitForMultipleObjects(2, &hWait[0],
                                                FALSE, INFINITE, QS_ALLINPUT);

                  if((WAIT_OBJECT_0 + 0) == dwResult || (WAIT_OBJECT_0 + 1) == dwResult)
                  {
                        //Our process was killed or Event was set
                        break;
                  }
                  else
                  {
                        //New messages have arrived.
                        continue;
                  }
            } //End of message while loop.
      }while(0);//End of Main while loop

      if(hWait[0])//Close our event
      {
            CloseHandle(hWait[0]);
            hWait[0] = NULL;
      }

      (void)::SetWindowLong(AfxGetMainWnd()->m_hWnd, GWL_WNDPROC, (LONG)prev_windowproc);

      return fRetVal;
}


BOOL CALLBACK ModalEnumProc(IN HWND PhWnd, IN LPARAM lParam)
{
      if(PhWnd)
      {
            //Get the foreground window
            //DWORD dwThreadID = ::GetWindowThreadProcessId(::GetForegroundWindow(), NULL);

            //DWORD dwCurThreadID = ::GetCurrentThreadId();

            //Connect to the actual foreground window thread
            //::AttachThreadInput(dwCurThreadID, dwThreadID, TRUE);

            //Set focus to this our spawned application
            ::SetForegroundWindow(PhWnd);
            ::SetFocus(PhWnd);

            //Disconnect the actual foreground windows thread
            //::AttachThreadInput(dwCurThreadID, dwThreadID, FALSE);
      }

    return TRUE;
}