PRB: Modal Dialog Box Prevents Calls to PreTranslateMessage

RESOLUTION

1. Use a modeless dialog box to simulate a modal dialog box. To do this, create a modeless dialog box, and then disable the application's main frame window. This method causes the normal message processing sequence to be followed, so the PreTranslateMessage function is called. The application's main window can be disabled by using this:

         AfxGetApp()->m_pMainWnd->EnableWindow(FALSE)
   						

   This window should be re-enabled once the dialog box has been destroyed. Use the following call to do it:

         AfxGetApp()->m_pMainWnd->EnableWindow(TRUE)
   						

   One possible place to do this might be in the CDialog-derived object's PostNcDestroy function that gets called when the dialog box window itself (the HWND) is destroyed.
   
   If you have multiple top-level windows in your application you may also want to disable the other windows. This can be done for the other windows in the same way -- by using EnableWindow.
2. If a modal dialog box seems necessary, perform the additional message processing by overiding the CWinApp::ProcessMessageFilter function. The ProcessMessageFilter function gets called for all messages when a modal dialog box exists. This is set up for you by MFC using a WH_MSGFILTER hook. See the ProcessMessageFilter documentation for details. The following sample code illustrates this concept:

      BOOL CMyApp::ProcessMessageFilter(int code, LPMSG lpMsg)
      {
        // Check to see if the modal dialog box is up
        if (m_hwndDialog != NULL)
          if (lpMsg->hwnd == m_hwndDialog ||
              ::IsChild(m_hwndDialog, lpMsg->hwnd))
            {
              // Use the global IsChild() function to get
              // messages destined for the dialog's controls
              // Perform customized message processing here
            }
        return CWinApp::ProcessMessageFilter(code, lpMsg);
      }
   						

// The OnInitDialog to initialize m_hwndDialog
// 
CMyDialog::OnInitDialog()
{
  CDialog::OnInitDialog();
  ((CMyApp *)AfxGetApp())->m_hwndDialog=m_hWnd;
}

// When the dialog is destroyed restore m_hwnDialog to NULL
// 
void CMyDialog::PostNcDestroy()
{
  CDialog::PostNcDestroy();
  ((CMyApp *)AfxGetApp())->m_hwndDialog=NULL;
}

// The CWinApp object's constructor to initialize m_hwndDialog
CMyApp::CMyApp()
{
  m_hwndDialog=NULL;
}