function buttondown( buttonname )
  {
    if (document.images) {
      document[buttonname].src = eval( buttonname + "down.src" );
    }
  }
  function buttonup ( buttonname )
  {
    if (document.images) {
      document[buttonname].src = eval( buttonname + "up.src" );
    }
  }
  function buttonclick ( buttonname )
  {
    if (document.images) {
      document[buttonname].src = eval( buttonname + "click.src" );
    }
  }