Bug in CMDIClientAreaWnd::EnableMDITabs()? recursive call

Question

I use LoadMDIState() in CMyApp::Initintance() to load/restore previous MDI-Doc's window positions.

if (cmdInfo.m_nShellCommand == CCommandLineInfo::FileNew)
{
    if (!pMainFrame->LoadMDIState(GetRegSectionPath()))
    {
        m_pStartDocTemplate->OpenDocumentFile(NULL);    // Load previous Document
    }
}

It works if his internal state during Serialize() is set to

CMDIClientAreaWnd::m_bTabIsEnabled = FALSE;

But It crashes if son internal state is

CMDIClientAreaWnd::m_bTabIsEnabled = TRUE;

I have investigate this bug in MFC source codes, and see a recursive calls in

void CMDIClientAreaWnd::EnableMDITabs(BOOL bEnable, const CMDITabInfo& params)
{
  if (m_bIsMDITabbedGroup)
  {
    EnableMDITabbedGroups(FALSE, params);
  }
  :
}


void CMDIClientAreaWnd::EnableMDITabbedGroups(BOOL bEnable, const CMDITabInfo& mdiTabParams)
{
  if (m_bTabIsEnabled)
  {
    EnableMDITabs(FALSE, mdiTabParams);
  }
  :
}

Is this a bug? And how to solve this problem for the MDI tabbed Views?

score 2 · Accepted Answer · answered Sep 26 '16 at 14:23

Solved by the comment in MFC source code itself.

CMDIChildWndEx* CMainFrame::CreateDocumentWindow(LPCTSTR lpcszDocName, CObject* pObj)
{
  return CMDIFrameWndEx::CreateDocumentWindow(lpcszDocName, pObj);
  ASSERT(FALSE);
  TRACE0("If you use save/load state for MDI tabs, you must override this method in a derived class!\n");
  return NULL;
}

I have overrided this in CMainframe, and it works.

CMDIChildWndEx* CMainFrame::CreateDocumentWindow(LPCTSTR lpcszDocName, CObject* pObj)
{
    CDocument* pDoc = NULL;
    pDoc = AfxGetApp()->OpenDocumentFile(lpcszDocName);

    if (pDoc != NULL)
    {
        POSITION pos = pDoc->GetFirstViewPosition();

        if (pos != NULL)
        {
            CView* pView = pDoc->GetNextView(pos);
            return DYNAMIC_DOWNCAST(CMDIChildWndEx, pView->GetParent());
        }
    }
}

return NULL;

Bug in CMDIClientAreaWnd::EnableMDITabs()? recursive call

1 Answers1