defaultStep=10;
step=defaultStep;

function scrollDivDown(id){
document.getElementById(id).scrollTop+=step;
} 

function scrollDivUp(id){
document.getElementById(id).scrollTop-=step; 
} 

timerDown=""; 
timerUp=""; 

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

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