var TO;

function Scroll(id,dis,pos){
    var obj=document.getElementById(id)
    var temp = obj.scrollTop;
    obj.scrollTop=obj.scrollTop+dis;
    
    if (id == 'texas_links') { 
        if (obj.scrollTop == 0) {
            document.getElementById("top").src = "_assets/img/btn_arrow_up-grey.gif";
        } else if (temp == obj.scrollTop) {
            document.getElementById("bottom").src = "_assets/img/btn_arrow_down-grey.gif";
        }

        if (obj.scrollTop == 1) {
            document.getElementById("top").src = "_assets/img/btn_arrow_up.gif";
        }
        if (obj.scrollTop == (temp - 1)) {
            document.getElementById("bottom").src = "_assets/img/btn_arrow_down.gif";
        }
    } else if (id == 'nymex_links') {
        if (obj.scrollTop == 0) {
            document.getElementById("top2").src = "_assets/img/btn_arrow_up-grey.gif";
        } else if (temp == obj.scrollTop) {
            document.getElementById("bottom2").src = "_assets/img/btn_arrow_down-grey.gif";
        }

        if (obj.scrollTop == 1) {
            document.getElementById("top2").src = "_assets/img/btn_arrow_up.gif";
        }
        if (obj.scrollTop == (temp - 1)) {
            document.getElementById("bottom2").src = "_assets/img/btn_arrow_down.gif";
        }
    }

    if (pos){
        obj.scrollTop=pos;
    } else {TO=setTimeout( function(){ Scroll(id,dis); },10); }
}