defaultStep=1 
step=defaultStep 

function scrollDivDown(id){
clearTimeout(timerDown) 
document.getElementById(id).scrollTop-=step 
timerDown=setTimeout("scrollDivDown('"+id+"')",10)
} 

function scrollDivUp(id){
clearTimeout(timerUp)
document.getElementById(id).scrollTop+=step 
timerUp=setTimeout("scrollDivUp('"+id+"')",10)
} 

timerDown="" 
timerUp="" 

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

function setScrollerHeight() {
var divHeight = document.getElementById("insideContainer").offsetHeight;
if(divHeight - 118 <= 307) {
  divHeight = 307;
} else {
  divHeight = divHeight - 118;
}
var scrollerDiv =  document.getElementById('dockMenuDiv');
scrollerDiv.style.height = (divHeight) + "px";
}

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

window.onload = setScrollerHeight;