C / C++ / MFC

CDialog
  CMFCPropertyGridCtrl
    Subclassed CMFCPropertyGridProperty to use my own CEdit Class, AutoCompleteEditBox (override CreateInPlaceEdit).
       CEdit
          CListBox

void AutoCompleteEditBox::ShowListBox()
{
    if ( !m_ListBox.GetSafeHwnd() )
    {
        UINT extendedStyle = WS_EX_CONTROLPARENT | WS_EX_TOOLWINDOW|WS_EX_WINDOWEDGE|WS_EX_TOPMOST;
        UINT style = LBS_NOTIFY|WS_POPUP|WS_BORDER|WS_VISIBLE|WS_VSCROLL;

/// I tried setting the parent to different CWnd (The dialog, the CMFCPropertyGridCtrl...) 
        CWnd* parent = nullptr;
        if ( m_ParentWindow )
        {
            parent = m_ParentWindow;
        }
        else
        {
            parent= GetParent();
        }

        BOOL ret = m_ListBox.CreateEx(extendedStyle, _TEXT("LISTBOX"),NULL,style, CRect( 0,0,0,0), parent, 0 , this);
//// At this point the HWND of the list box is 0xFEEEFEEE.

        ASSERT( ret);
    }
}

int SuggestionListBox::OnCreate(LPCREATESTRUCT lpCreateStruct) 
{
    if (CListBox::OnCreate(lpCreateStruct) == -1)
        return -1;

//// At this point the HWND of the listbox is valid.
    m_pEdit = (AutoCompleteEditBox*)lpCreateStruct->lpCreateParams; 
    return 0;
}