Question on CWnd::PreTranslateMessage

[LifeIsSuffering]

Here’s my code sample,

BOOL XBaseWindow::PreTranslateMessage(MSG* pMsg)
{
    // TODO: Add your specialized code here and/or call the base class
    switch (pMsg->message)
    {
    case WM_LBUTTONUP:
    case WM_LBUTTONDOWN:
        {
            POINT pt = pMsg->pt;
            this->ScreenToClient(&pt);                       

            // do something with mouse position
            int ret = this->preProcessMouseEvent(pt.x, pt.y);

		  // if should eat this event, stop its propagation
            if (ret == RESULT_GOT_EATEN)
            {
                return TRUE;
            }
        }
        break;
    case WM_KEYDOWN:
    case WM_KEYUP:
        {
            // do something with kb value
            int ret = this->preProcessKbEvent((int32_t)pMsg->wParam);
            if (ret == RESULT_GOT_EATEN)
            {
                return TRUE;
            }
        }
        break;
    default:
        break;
    }

    return __super::PreTranslateMessage(pMsg);
}

My purpose was to handle those messages accordingly and prevent them from further propagation if necessary, so I have to use PreTranslateMessage to intercept mouse and kb messages.

At the first, it worked. But, if I constructed two XBaseWindow instances, and one was parent window of the other, the problem showed up. For example, when I clicked on the child window, the mouse LBD message was unexpectedly intercepted twice, one in child PreTranslateMessage and one in parent PreTranslateMessage.

I was thinking about that if I have misunderstanding of usage of PreTranslateMessage.

How could I fix it? Thx in advance.