FIX: Assert in Appui1.cpp Line 215 in MFC SDI/MDI application

View products that this article applies to.

This article was previously published under Q193102

SYMPTOMS

When you try to display a modal window without explicitly specifying a parent in a command handler of an MFC SDI/MDI application, where the frame window is destroyed in the command handler before displaying the modal window, you might get an assertion in CCmdTarget::GetRoutingFrame_() (Appui1.cpp line: 215) with debug builds.

In the release builds of the application, modal windows may behave similar to modeless windows. This will also be the case if you update an MFC application from Visual C++ 5.0 to Visual C++ 6.0 (both versions of Visual C++ use the MFC DLL named MFC42.dll).

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CAUSE

Modal windows now use the routing frame data member (m_pRoutingFrame) of the thread state to decide on the owner in GetSafeOwner(). The problem is that the CFrameWnd set as the thread state's current routing frame is deleted, but the thread state is not updated to reflect that fact.

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RESOLUTION

Set the thread state's current routing frame to NULL in the destructor of your CFrameWnd derived class that is being destroyed:

CMyFrameWnd::~CMyFrameWnd()
   {

      if( AfxGetThreadState()->m_pRoutingFrame == this )
      {
         AfxGetThreadState()->m_pRoutingFrame = NULL;
      }
   }

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STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug has been fixed in the Visual Studio 6.0 Service Pack 1.

To obtain this service pack, please see:

http://msdn2.microsoft.com/en-us/vstudio/Aa718362.aspx (http://msdn2.microsoft.com/en-us/vstudio/Aa718362.aspx)

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MORE INFORMATION

The MFC frame windows affected by this problem can be of type CFrameWnd, CMDIFrameWnd, CMDIChildWnd, and COleIPFrameWnd.

The MFC modal windows affected are:

Dialog
CPropertySheet
Ole Property Sheet [invoked through [ASCII 150] OleObject::DoVerb(OLEIVERB_PROPERTIES)]
COleBusyDialog
Message Box [invoked through AfxMessageBox()]
MAPI modal window [when calling MAPISendMail()]
SQL Driver Connection dialog box [when calling SQLDriverConnect()]

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Steps to Reproduce Behavior

Use AppWizard to generate an MFC exe that is an MDI-based application.
Use ClassWizard to override OnCloseDocument of the CDocument class generated by AppWizard.

Edit the OnCloseDocument member function as shown here:

      void CMyDoc::OnCloseDocument()
      {
         CDocument::OnCloseDocument();
         AfxMessageBox("The Document is Closed");
      }

Build and run the application.
On the File menu, click Close.

RESULTS: The following error appears:

"Debug Assertion Failed! File: Appui1.cpp line: 215".

To correct this problem in the case mentioned above, add the following code in the destructor for CChildFrame:

CChildFrame::~CChildFrame()
   {

      if( AfxGetThreadState()->m_pRoutingFrame == this )
      {
         AfxGetThreadState()->m_pRoutingFrame = NULL;
      }
   }

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