function changimg(obj, i)
{
	obj.src = "images/bt" + i + ".gif";
}

function showimg(id)
{
	var obj = document.getElementById(id);
	if (obj.style.display == "none")
	{
		obj.style.display = "";
	}
	else
	{
		obj.style.display = "none";
	}
}