var speed;
var currentpos=0,alt=1,curpos1=0,curpos2=-1;
var scrollage=0;
var sens;

function scrollwindow(sens){
if (sens=="B") {
   speed=3;
   scrollage=setTimeout("scrollwindow('B')",10);
}
else {
   speed=-3;
   scrollage=setTimeout("scrollwindow('H')",10);
}
currentpos=parent.droite.document.body.scrollTop+speed;
parent.droite.window.scroll(0,currentpos);
}

function startfin(){
clearTimeout(scrollage);
}