var timer_id;

function scroll_iframe(frm,inc,miLargeur) 
{
  if (timer_id) clearTimeout(timer_id);
  if (window.frames[frm]) 
  {
    var deplacement=window.frames[frm].document.body.scrollLeft;
    if (deplacement>miLargeur) 
    {
    //window.frames[frm].document.body.scrollLeft=0
 	window.frames[frm].scrollBy(-deplacement, 0);
    };
    
    window.frames[frm].scrollBy(inc, 0);
   
    timer_id = setTimeout("scroll_iframe('" + frm + "'," + inc + "," + miLargeur + ")", 15);
  }
}