function scroll(){

    var tmt;

    var cntnt = document.getElementById('Scroll');

    var arr   = document.getElementById('arrow_up');

    if( !cntnt && !arr ) return;

    var arrow = arr.src.substr(arr.src.length-5,1);

    var set_a = (arrow == 'A' ? 'A' : 'C');

    var set_b = (arrow == 'A' ? 'B' : 'D');

    var upp   = arr.parentNode;

    upp.onmouseover = function(){

	upp.firstChild.src="images/b_arrow_up-"+set_b+".gif";

	tmt = window.setInterval('customScrollBy(-10)',100);

    };

    upp.onmouseout = function(){

	upp.firstChild.src="images/b_arrow_up-"+set_a+".gif";

	window.clearInterval(tmt);

    };

    downn = document.getElementById('arrow_dn').parentNode;

    downn.onmouseover = function(){

	downn.firstChild.src="images/b_arrow_dn-"+set_b+".gif";

	tmt = window.setInterval('customScrollBy(10)',100);

    };

    downn.onmouseout = function(){

	downn.firstChild.src="images/b_arrow_dn-"+set_a+".gif";

	window.clearInterval(tmt);

    };

}

function customScrollBy(amnt){

    var cntnt = document.getElementById('Scroll');

    cntnt.scrollTop += amnt;

}



addEvent(window, 'load', scroll);