Microsoft KB Archive/153427

= PRB: Controls Not Initialized in CPropertyPage::OnInitDialog =

Article ID: 153427

Article Last Modified on 11/21/2006

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APPLIES TO

 Microsoft Foundation Class Library 4.2, when used with:  Microsoft Visual C++ 4.2 Enterprise Edition

 Microsoft Visual C++ 4.2 Professional Edition 

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This article was previously published under Q153427



SYMPTOMS
Initializing controls in a CPropertyPage in CPropertyPage:: OnInitDialog by way of their associated member variables doesn't work. For example, to initialize an edit control that is associated with a CString member variable called "m_strData", you could do the following: BOOL CMyPage::OnInitDialog {   CPropertyPage::OnInitDialog; m_strData = _T("Hello"); return TRUE; } The edit control will not be set to "Hello" at run time. This used to work in MFC 4.0 and 4.1.



CAUSE
Data is transferred from member variables to their associated controls when UpdateData is called (UpdateData calls DoDataExchange which calls DDX functions). UpdateData is called by OnInitDialog and OnSetActive. This caused UpdateData to be called twice when a CPropertyPage is first created. This was a problem in MFC 4.0 and MFC 4.1. It was fixed in MFC 4.2. OnSetActive now checks a flag (m_bFirstSetActive) to see if this is the first time it is being called. If it is the first time, then UpdateData is not called.

As a consequence, UpdateData will not be called again right after OnInitDialog when OnSetActive is called during the creation of the property page.



RESOLUTION
You can initialize member variables in the CPropertyPage's constructor or right before the call to CPropertyPage::OnInitDialog. CMyPage::CMyPage : CPropertyPage(CMyPage::IDD) {   //AFX_DATA_INIT } or BOOL CMyPage::OnInitDialog {   m_strData = _T("Hello"); // OnInitDialog will call UpdateData CPropertyPage::OnInitDialog; return TRUE; }

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STATUS
This behavior is by design.

Additional query words: 4.20 4.10 4.00

Keywords: kbctrlcreate kbprb kbpropsheet kbuidesign KB153427

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