function mouse_event(img_id, event)
{
  var img;
  if(document.getElementById != null)
  {
    img = document.getElementById(img_id);
    if(img != null)
    {
      if(event == "load")
      {
        img.src_up = mouse_event.arguments[2];
        img.src_over = mouse_event.arguments[3];
        img.src_down = mouse_event.arguments[4];
      }
      else if(event == "down")
      {
        if(img.src_down != null) img.src = img.src_down;
      }
      else if(event == "out")
      {
        if(img.src_up != null) img.src = img.src_up;
      }
      else if(((event == "over") || (event == "up")) && (img.src_over != null)) img.src = img.src_over;
    }
  }
}