if ( document.images )
{
  home_on = new Image ( );
  home_off = new Image ( );

  home_on.src = "http://tenisdecorrida.com.br/wp-content/themes/tenisdecorrida/images/home2.gif";
  home_off.src = "http://tenisdecorrida.com.br/wp-content/themes/tenisdecorrida/images/home.gif";
}

function button_on ( imgId )
{
  if ( document.images )
  {
    butOn = eval ( imgId + "_on.src" );
    document.getElementById(imgId).src = butOn;
  }
}

function button_off ( imgId )
{
  if ( document.images )
  {
    butOff = eval ( imgId + "_off.src" );
    document.getElementById(imgId).src = butOff;
  }
}