void CTopDlgDemoDlg::StayOnTop() const
{
 CRect rect;

 // get the current window size and position
 GetWindowRect( rect );

 // now change the size, position, and Z order
 // of the window.
 ::SetWindowPos(m_hWnd ,       // handle to window
                HWND_TOPMOST,  // placement-order handle
                rect.left,     // horizontal position
                rect.top,      // vertical position
                rect.Width(),  // width
                rect.Height(), // height
                SWP_SHOWWINDOW // window-positioning options);
}

// add a control button and command handler for the button to your dialog.
// then invoke StayOnTop().
void CTopDlgDemoDlg::OnBtnClick()
{
 // make this dialog always on top.
 StayOnTop();
}