C / C++ / MFC

BOOL CMyDialog::OnInitDialog()
{
    CDialog::OnInitDialog();
 
    m_SomeButton.EnableWindow(...);
 
    return TRUE;
}

void SomeWindow::Button1Click()
{
  Pop up a dialog asking for username/passwordd.
  if(!DoSomeFunction(username, password))
  {
     AfxMessageBox("Nice try, buddy!");
  }
}

..
bool DoSomeFunction(username, password)
{
  check username and password
  If incorrect, return false
  Else do the forbidden function and return true
}

HBRUSH CMyProgramView::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor) 
{
	HBRUSH hbr = CFormView::OnCtlColor(pDC, pWnd, nCtlColor);
	
	INT nIDCtl = pWnd->GetDlgCtrlID();
	switch(nIDCtl)
	{
	case IDC_TEXT_BOX: 
		if (!m_strTextBox.IsEmpty())
		{
			// Change background color to white so that the
			// text is easier to read.
			pDC->SetBkColor(RGB(255, 255, 255));
			CBrush br;
			br.CreateSolidBrush(RGB(255, 255, 255));
			hbr = (HBRUSH)br;
			br.Detach();
		}
                // else
                // use default background color
		break;
        }
	return hbr;
}