PRB: No ANSI Notifications from Control Created in OnCreate

The information in this article applies to:

• The Microsoft Foundation Classes (MFC) included with: Microsoft Visual C++, 32-bit Edition, versions 2.1, 2.2, 4.0, 4.1

SYMPTOMS

No notification messages are received from a common control that is created in the OnCreate function (the WM_CREATE handler) of a CFormView or CDialog. Closer inspection reveals that notifications are being sent, but they are the UNICODE versions of the notifications.

CAUSE

The common controls send a WM_NOTIFYFORMAT message when they are first created to determine if they should send ANSI or UNICODE notifications to the parent window.

The default processing of WM_NOTIFYFORMAT for a dialog box returns NFR_UNICODE until after the dialog box window has been created. At the point when the WM_CREATE message is sent, the dialog box still returns NFR_UNICODE in response to a WM_NOTIFYFORMAT message.

A CFormView is really a dialog box, so this is a problem for the CFormView class as well as the CDialog class.

RESOLUTION

Here are two ways to work around this problem:

• Don't create the control in the WM_CREATE handler. If the control is created at a later point, this problem won't occur. For a CDialog- derived class, create the control in the OnInitDialog function. For a CFormView-derived class, create the control in the OnInitialUpdate function.

  -or-

• Handle the WM_NOTIFYFORMAT message in the CDialog- or CFormView-derived class and respond with the NFR_ANSI code. The WM_NOTIFYFORMAT message is not available in ClassWizard, so you'll need to manually enter the ON_MESSAGE macro for the message as follows:

        BEGIN_MESSAGE_MAP(CMyDialog, CDialog)
            //{{AFX_MSG_MAP(CMyDialog)
            ... message map entries created by classwizard
            //}}AFX_MSG_MAP
            ... other manually created message map entries
            ON_MESSAGE(WM_NOTIFYFORMAT, OnNotifyFormat) // ADD THIS LINE
        END_MESSAGE_MAP()
  
     Add the prototype for this function to the class definition:
  
        class CMyDialog : public CDialog
        {
            ... other class members
        protected:
            afx_msg LRESULT OnNotifyFormat(WPARAM wParam,LPARAM lParam);
        };
  
     For more information on how to do this, please see the following article
     in the Microsoft Knowledge Base:
  
        ARTICLE-ID: Q99848
        TITLE     : Use ON_MESSAGE() Macro to Map Less-Common Messages
  
     The OnNotifyFormat function should be implemented as follows:
  
        LRESULT CMyDialog::OnNotifyFormat(WPARAM wParam,LPARAM lParam)
        {
          #ifdef _UNICODE
            return NFR_UNICODE;
          #else
            return NFR_ANSI;
          #endif
        }
  
  

STATUS

Microsoft has confirmed this to be a bug in Microsoft Windows NT. It is not a bug in MFC. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.