Re: Prevent Dialog from Being Shown in OnShowWindow

I'm working on a modeless dialog which needs to get some data each time it is
shown. If it fails to obtain the data, I want to show a message box and
prevent the dialog from being shown. I've tried handling this in
OnShowWindow:

void CMyDialog::OnShowWindow(BOOL bShow, UINT nStatus)
{
   CDialog::OnShowWindow(bShow, nStatus);

   if (bShow)
   {
      // get data here
      AfxMessageBox(_T("Failed to get data!"), MB_ICONERROR | MB_OK);
      ShowWindow(SW_HIDE);
   }
}

Calling ShowWindow inside OnShowWindow doesn't seem to have an effect. The
dialog is shown anyway. Commenting out the call to the base class has no
effect, and neither does setting bShow to FALSE. The only thing I've found
that works is doing a SendMessage(WM_CLOSE). However, then the dialog
flickers on the screen, as it is clearly shown and then hidden very quickly.

What's the best way to do this? Can you "cancel the showing" from inside
OnShowWindow, or is that too late?