skjul scroll knapper

Hejsa
Jeg mangler lige en måde at skjule mine scroll knapper når min tekst ikke er lang nok til at scrolle eller der slet ikke er en tekst.
Den div knapperne ligger i hedder divControl.
Her er koden...

function lib_bwcheck(){ //Browsercheck (needed)
    this.ver=navigator.appVersion
    this.agent=navigator.userAgent
    this.dom=document.getElementById?1:0
    this.opera5=this.agent.indexOf("Opera 5")>-1
    this.ie5=(this.ver.indexOf("MSIE 5")>-1 && this.dom && !this.opera5)?1:0;
    this.ie6=(this.ver.indexOf("MSIE 6")>-1 && this.dom && !this.opera5)?1:0;
    this.ie4=(document.all && !this.dom && !this.opera5)?1:0;
    this.ie=this.ie4||this.ie5||this.ie6
    this.mac=this.agent.indexOf("Mac")>-1
    this.ns6=(this.dom && parseInt(this.ver) >= 5) ?1:0;
    this.ns4=(document.layers && !this.dom)?1:0;
    this.bw=(this.ie6 || this.ie5 || this.ie4 || this.ns4 || this.ns6 || this.opera5)
    return this
}
var bw=new lib_bwcheck()

timSpeed = 50
contHeight = 170

function makeScrollObj(obj,nest){
    nest=(!nest) ? "":'document.'+nest+'.'       
    this.el=bw.dom?document.getElementById(obj):bw.ie4?document.all[obj]:bw.ns4?eval(nest+'document.'+obj):0;
      this.css=bw.dom?document.getElementById(obj).style:bw.ie4?document.all[obj].style:bw.ns4?eval(nest+'document.'+obj):0;       
    this.height=bw.ns4?this.css.document.height:this.el.offsetHeight
    this.top=b_gettop                                       
    return this
}

var px = bw.ns4||window.opera?"":"px";

function b_gettop(){
    var gleft=(bw.ns4 || bw.ns6)?parseInt(this.css.top):eval(this.css.pixelTop);
    return gleft;
}

var scrollTim = 1;
var active = 0;

function scroll(speed){
    clearTimeout(scrollTim)
    way = speed>0?1:0
    if ((!way && oScroll[active].top()>-oScroll[active].height+contHeight) || (oScroll[active].top()<0 && way)){
        oScroll[active].css.top = (oScroll[active].top()+speed)+px
        scrollTim = setTimeout("scroll("+speed+")",timSpeed)
    }
}

function noScroll(){
    clearTimeout(scrollTim)
}

function changeActive(num){
    oScroll[active].css.visibility = "hidden"
    active = num
    oScroll[active].css.top = 0+px
    oScroll[active].css.visibility = "visible"
}

function scrollInit(){
    oScroll = new Array()
   
    oScroll[0] = new makeScrollObj('divScroll1','divCont')
   
    oScroll[0].css.left = 0+px
    oScroll[0].css.top = 0+px
    oScroll[0].css.visibility = "visible"
    oControl = new makeScrollObj('divControl')
    oControl.css.visibility = "visible"
}

onload = scrollInit;