BUG: Assertion Failure When Handling xN_SETFOCUS in CFormView (142274)
The information in this article applies to:
- The Microsoft Foundation Classes (MFC), when used with:
- Microsoft Visual C++, 32-bit Professional Edition 4.0
- Microsoft Visual C++, 32-bit Learning Edition 4.0
This article was previously published under Q142274 SYMPTOMS
Focus notifications (EN_SETFOCUS, BN_SETFOCUS, and so on) for controls in a
CFormView are usually handled in the CFormView class. Calling a function
that relies on the window handle of the control (m_hWnd) inside such a
handler may cause an assertion failure in Afxwin2.inl. This happens only if
the control is the first one in the tab order.
CAUSE
The assertion failure occurs because the focus handler for the control is
being called before OnInitialUpdate() is called for the CFormView.
RESOLUTION
To work around this problem, make sure that the m_hWnd member of the
control is not NULL before calling any function that relies on it.
STATUS
Microsoft has confirmed this to be a bug in the Microsoft products
listed at the beginning of this article. This bug was corrected in
Visual C++ 4.1.
Sample Code
The following illustrates calling SetSel in the for an Edit control.
void CSettestView::OnSetFocusEdit1()
{
if(NULL != m_Edit.m_hWnd)
m_Edit.SetSel( 0,1 );
}
| Modification Type: | Major | Last Reviewed: | 11/18/2003 |
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| Keywords: | kbBug kbDocView kbfix kbNoUpdate KbUIDesign kbVC410fix KB142274 |
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