var intervalID = '';
function scrollDown(bool){
	var  obj = document.getElementById('contentText');
	if(bool=='play') {
		obj.scrollTop += 2;
		intervalID = setTimeout("scrollDown('play')", 1);
	}
	if(bool=='stop') {
		clearTimeout(intervalID);
		return false;
	}	
	else return false;
}

function scrollUp(bool){
	var  obj = document.getElementById('contentText');
	if(bool=='play'){
		obj.scrollTop -= 2;
		intervalID = setTimeout("scrollUp('play')", 1);
	}
	if(bool=='stop') {
		clearTimeout(intervalID);
		return false;
	}	
	else return false;
}