// JavaScript Document
function scrollUpObject(id, pixels){
	pixels = Math.abs(parseInt(pixels));
	var obj = document.getElementById(id);
	if(obj != null){
		if(obj.scrollTop > 0){
			if(obj.scrollTop-pixels >= 0)
				obj.scrollTop = obj.scrollTop-pixels;
			else
				obj.scrollTop = 0;
		}
	}
}

function scrollDownObject(id, pixels){
	pixels = Math.abs(parseInt(pixels));
	var obj = document.getElementById(id);
	if(obj != null){
		obj.scrollTop = obj.scrollTop+pixels;
	}
}

function updateButton(buttonId, scrollId, is_top){
	var obj = document.getElementById(scrollId);
	var button = document.getElementById(buttonId);
	if(obj != null && button != null){
		if(is_top && obj.scrollTop == 0 || !is_top && obj.scrollTop == (obj.scrollHeight - obj.clientHeight)){
			button.className = "disabled";
		}else{
			button.className = "";
		}
	}
}

function scrollUp(pixels){
	scrollUpObject('scroll', pixels);
	updateButton('button_atras', 'scroll', 1);
	updateButton('button_continuar', 'scroll', 0);
}
function scrollDown(pixels){
	scrollDownObject('scroll', pixels);
	updateButton('button_atras', 'scroll', 1);
	updateButton('button_continuar', 'scroll', 0);
}