var wndPopup = null;

function ShowPopup(theURL)
{
  if(wndPopup != null && !wndPopup.closed)
  {
    wndPopup.close();
  }

  wndPopup = window.open(theURL,'popup','scrollbars=no,resizable=no,width=760,height=480');
  wndPopup.focus();
};