PRB: MFC Property Sheets Close When Using Transcriber for Pocket PC (304290)


The information in this article applies to:

  • Microsoft eMbedded Visual C++, Version:4.0
  • Microsoft Windows CE for the Pocket PC
This article was previously published under Q304290

SYMPTOMS

When you are using Microsoft Transcriber on a Pocket PC, a Microsoft Foundation Classes (MFC)-implemented property sheet dialog box disappears abruptly when you lift the stylus from the touch screen.

CAUSE

Modal property sheet dialog boxes in MFC are implemented through the use of a modeless dialog box and continual checking whether the active property page is NULL through the use of the PSM_GETCURRENTPAGEHWND message in the ContinueModal method. As soon as this message returns NULL, MFC assumes the user has clicked the OK button, and MFC closes the property sheets by returning FALSE from ContinueModal. However, lifting the stylus from the screen when using Microsoft Transcriber immediately causes the PSM_GETCURRENTPAGEHWND to return NULL.

RESOLUTION

To work around the problem override the ContinueModal method for the CPropertySheet-derived class. Instead of checking if the active page window handle has become NULL, check a custom implemented flag. The flag can be set by the OnOK method of the first PropertyPage. Clear this flag during the construction of the CPropertySheet-derived class.

MORE INFORMATION

The following code provides a brief example of the prescribed resolution. 
CPropSheet::CPropSheet(UINT nIDCaption, CWnd* pParentWnd, UINT iSelectPage)
	:CPropertySheet(nIDCaption, pParentWnd, iSelectPage), uLastmsg(0)
{
	m_bOKToClose = FALSE;
}

BOOL CPropSheet::ContinueModal() 
{
	// TODO: Add your specialized code here and/or call the base class
	if (!CWnd::ContinueModal())
		return FALSE;


	if (m_bOKToClose)  // means the OK button was pressed
		return FALSE;

	return TRUE;

}

void CPropPage1::OnOK() 
{
	// TODO: Add your specialized code here and/or call the base class

	// let the CPropSheet::ContinueModal function know it's ok to close
	CPropSheet *pSheet = (CPropSheet *)GetParent();
	pSheet->m_bOKToClose = TRUE;

	CPropertyPage::OnOK();
}

It is not necessary set the m_bOKToClose flag in the OnOK handler of each of the property pages. If OK is clicked while the second property page is displayed on top, OnOK is still called for the first property page and subsequent OnOK handlers are called before ContinueModal is called.

REFERENCES

For more information on Microsoft Transcriber, see the Mobile Devices Pocket PC Web page:

http://www.pocketpc.com

For more information about property sheets and MFC, see "CPropertySheet" in the eMbedded Visual Tools 3.0 Help or on MSDN Online:

http://msdn.microsoft.com/library/en-us/wcemfc/htm/cpropsht.asp?frame=true

Modification Type:MinorLast Reviewed:7/27/2004
Keywords:kbprb KB304290
©2004 Microsoft Corporation. All rights reserved.