defaultStep=12 
step=defaultStep 

function scrollDivDown(id){
clearTimeout(timerDown); 
document.getElementById(id).scrollTop+=step; 
timerDown=setTimeout("scrollDivDown('"+id+"')",100);

} 

function scrollDivUp(id){
clearTimeout(timerUp);
document.getElementById(id).scrollTop-=step; 
timerUp=setTimeout("scrollDivUp('"+id+"')",100);
} 

timerDown="" ;
timerUp="" ;

function stopMe(){
clearTimeout(timerDown); 
clearTimeout(timerUp);
}

// document.onmousemove=function(){stopMe();}